JP2016051504A - Positive electrode active material for nonaqueous secondary battery, positive electrode for nonaqueous secondary battery, nonaqueous secondary battery, and on-vehicle nonaqueous secondary battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive electrode active material for a nonaqueous secondary battery which is wide in SOC range where a high output can be obtained, and high in effective capacity per unit area.SOLUTION: A positive electrode active material for a nonaqueous secondary battery comprises: a first lamellar solid solution compound 101A including nickel and manganese; a second lamellar solid solution compound 102A including nickel and manganese, and different from the first lamellar solid solution compound 101A in the ratio of the atomic concentration of the nickel and that of the manganese. The positive electrode active material further comprises: at least two kinds of lamellar solid solution compound secondary particles 110A and 120A which are different from each other in average particle diameter. Supposing that of average particle diameters of the two kinds of lamellar solid solution compound secondary particles 110A and 120A, the large particle diameter is D1 and the small particle diameter is D2, D1/D2≥2 holds. Supposing that the mass ratio of the lamellar solid solution compound secondary particles 110A and 120A having the average particle diameter D1 is W1, and the mass ratio of the lamellar solid solution compound secondary particles having the average particle diameter D2 is W2, 0.2≤W1/(W1+W2)≤0.9 holds.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a positive electrode active material for a non-aqueous secondary battery, a positive electrode for a non-aqueous secondary battery, a non-aqueous secondary battery, and a vehicle-mounted non-aqueous secondary battery module.

  One type of non-aqueous secondary battery in which a non-aqueous electrolyte mediates electrical conduction between electrodes is a lithium ion secondary battery. A lithium ion secondary battery is a secondary battery in which lithium ions are responsible for electrical conduction between electrodes in charge and discharge reactions. Compared to other secondary batteries such as nickel-hydrogen storage batteries and nickel-cadmium storage batteries, the energy density Is high and the memory effect is small. Therefore, from small power sources such as portable electronic devices and household electric devices, stationary power sources such as power storage devices, uninterruptible power supply devices, power leveling devices, drive power sources for ships, railways, hybrid vehicles, electric vehicles, etc. Applications are expanding to medium and large power supplies, and further improvements in battery performance are required. For example, in-vehicle applications such as hybrid vehicles and electric vehicles, there is a demand for higher energy density for increasing the cruising range and higher output for improving acceleration response.

LiM1O ₂ (M1 is represented by LiCoO ₂ , LiCo _1/3 Ni _1/3 Mn _1/3 O _2, etc. as a kind of positive electrode active material responsible for the electrochemical reaction of the positive electrode in the lithium ion secondary battery. It represents an element such as Co, Ni, Mn, etc.). This layered oxide is relatively easy to manufacture and has been widely used as a positive electrode active material. However, since the discharge capacity of the layered oxide is as small as about 150 Ah / kg to 180 Ah / kg, in recent years, it is expressed as Li ₂ MnO ₃ —LiM ₂ O ₂ (M ₂ represents an element such as Co, Ni, or Mn). Development of a positive electrode active material using a layered solid solution compound is underway. A positive electrode active material using a layered solid solution compound is expected as a positive electrode active material exhibiting a high capacity.

For example, Patent Document 1 discloses α-NaFeO ₂ as a positive electrode active material for a lithium ion secondary battery having a large discharge capacity, particularly a lithium secondary battery capable of increasing the discharge capacity in a potential region of 4.3 V or less. A positive electrode active material that includes a solid solution of a lithium transition metal composite oxide having a type crystal structure and that defines the composition ratio of Li, Co, Ni, and Mn contained in the solid solution within a specific range is disclosed.

Patent Document 2 discloses the following general formula: xLi [Li _1/3 M1 _2/3 ] O ₂ · as a positive electrode for a lithium ion secondary battery in which capacity deterioration due to charge / discharge at a high potential is suppressed. _{(1-x) LiM2O 2 (} 1) ( wherein M1 is at least one metallic element average oxidation state is 4+, M2 is a transition metal element of at least one: 0 <x <1) with The solid solution compound shown and the following general formula: LiNi _1-ab M3 _a M4 _b O ₂ (2) (where M3 is Al and / or Mg, M4 is Co, Mn, Fe, Cu And at least one metal element selected from the group consisting of Cr: 0.3 ≦ a ≦ 0.5, 0 ≦ b ≦ 0.2) having a lithium nickel composite oxide having a layered structure represented by: Disclosure of positive electrode for lithium ion secondary battery It has been.

Further, Patent Document 3 describes a composition formula: Li _{1 + a} (Mn _b Co _c Ni _1-bc ) _1-a M _d O _2-e (where M is Al, Mg, Zr, Ti, Ba, B, Si and Fe, and a to e are 0.1 <a <0.25, 0.5 ≦ b <0.7, 0 ≦ c <1-b, 0 ≦ d ≦ 1 and 0 ≦ e ≦ 1), and the crystallite diameter D1 of the primary particles of the first lithium-containing compound satisfies 1200 nm ≦ D1 ≦ 1900 nm. The crystallite diameter D2 of the primary particles of the second lithium-containing compound satisfies 350 nm ≦ D2 ≦ 900 nm, and the mixing ratio of the first lithium-containing compound and the second lithium-containing compound is the first lithium-containing compound: second Lithium-containing compound = 80: 20-70 30, the positive electrode is disclosed for a secondary battery. In addition, according to the Example of patent document 3, both ratio Ni / Mn of nickel and manganese in a 1st lithium containing compound and a 2nd lithium containing compound is 0.2 / 0.6.

JP 2010-086690 A JP 2011-171012 A JP 2013-218787 A

  In general, a lithium ion secondary battery is charged with a state of charge (SOC) defined in an initial charge / discharge test of the battery in order to avoid deterioration of battery performance due to overcharge or overdischarge and to ensure battery life and safety. ) Is operating in a range narrower than the range of It is known that the conventional layered oxide has a high resistance at the end of discharge and exhibits a large voltage drop when trying to obtain a high output (large current). According to the techniques disclosed in Patent Document 1 and Patent Document 2, it is considered that a high capacity can be obtained in terms of battery performance, but since the high resistance region of the layered solid solution compound is not considered, the effective capacity is sufficient. May not improve.

  In addition, the layered solid solution compound has a lower specific gravity and a smaller particle diameter than conventional layered oxides, and a positive electrode using the layered solid solution compound has a lower density. Therefore, the capacity per volume is low. According to the technique disclosed in Patent Document 3, it is considered that a positive electrode having an increased volume density and a high capacity per volume can be obtained. However, since the high resistance region is not considered, the effective capacity is sufficiently high. May not improve.

  Therefore, a non-aqueous secondary battery that can obtain a high output in a wider SOC range and has a high effective capacity per volume is demanded. An object of the present invention is to provide a positive active material for a non-aqueous secondary battery having a wide SOC range capable of obtaining a high output and a high effective capacity per volume, a positive electrode for a non-aqueous secondary battery, a non-aqueous secondary battery, and The object is to provide a non-aqueous secondary battery module for vehicle use.

  In order to solve the above problems, a positive electrode active material for a non-aqueous secondary battery according to the present invention includes a first layered solid solution compound containing nickel and manganese, nickel and manganese, and the first layered solid solution compound. Includes a second layered solid solution compound in which the ratio of the atomic concentration of nickel and the atomic concentration of manganese is different, and includes at least two types of layered solid solution compound secondary particles having different average particle diameters, Mass ratio of layered solid solution compound secondary particles in which D1 / D2 ≧ 2 when the large particle diameter is D1 and the small particle diameter is D2 among the average particle diameters of the solid solution compound secondary particles, and the average particle diameter is D1. Is W 1 and the mass ratio of the layered solid solution compound secondary particles having an average particle diameter of D2 is W 2, 0.2 ≦ W1 / (W1 + W2) ≦ 0.9.

  The positive electrode active material for a non-aqueous secondary battery according to the present invention includes a first layered solid solution compound containing nickel and manganese, nickel and manganese, and the first layered solid solution compound is an atom of nickel. A layered solid solution compound secondary particle composed of the first layered solid solution compound and a layered structure composed of the second layered solid solution compound. Mass ratio of layered solid solution compound secondary particles in which D3 / D4 ≧ 2 when the large particle diameter is D3 and the small particle diameter is D4 out of the average particle diameter of the solid solution compound secondary particles, and the average particle diameter is D3 Is W 3 and the mass ratio of the layered solid solution compound secondary particles having an average particle diameter of D4 is W4, 0.2 ≦ W3 / (W3 + W4) ≦ 0.9.

  Moreover, the positive electrode for nonaqueous secondary batteries which concerns on this invention is characterized by including the said positive electrode active material for nonaqueous secondary batteries.

  The non-aqueous secondary battery according to the present invention includes the positive electrode for a non-aqueous secondary battery.

  Moreover, the non-aqueous secondary battery module for vehicles which concerns on this invention is provided with the said non-aqueous secondary battery.

  According to the present invention, a positive active material for a non-aqueous secondary battery, a positive electrode for a non-aqueous secondary battery, a non-aqueous secondary battery, and a non-vehicle-mounted non-aqueous secondary battery having a wide SOC range in which high output can be obtained and a high effective capacity per volume. An aqueous secondary battery module can be provided. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

It is a schematic diagram which shows one Embodiment of the positive electrode active material for non-aqueous secondary batteries. It is a schematic diagram which shows one Embodiment of the positive electrode active material for non-aqueous secondary batteries. It is a schematic diagram which shows one Embodiment of the positive electrode active material for non-aqueous secondary batteries. It is a schematic diagram which shows one Embodiment of the positive electrode active material for non-aqueous secondary batteries. It is a schematic diagram which shows one Embodiment of the positive electrode active material for non-aqueous secondary batteries. It is a schematic diagram which shows one Embodiment of the positive electrode active material for non-aqueous secondary batteries. It is a schematic diagram which shows one Embodiment of the positive electrode active material for non-aqueous secondary batteries. It is a schematic diagram which shows one Embodiment of the positive electrode active material for non-aqueous secondary batteries. It is a cross-sectional schematic diagram which shows an example of the non-aqueous secondary battery which concerns on this embodiment.

  Hereinafter, a positive electrode active material for a non-aqueous secondary battery, a positive electrode for a non-aqueous secondary battery, a non-aqueous secondary battery, an in-vehicle non-aqueous secondary battery module, and a manufacturing method thereof according to an embodiment of the present invention This will be described in detail.

  The positive electrode active material for a non-aqueous secondary battery according to this embodiment is used for a positive electrode provided in a non-aqueous secondary battery such as a lithium ion secondary battery. The positive electrode active material for a non-aqueous secondary battery is composed of a combination of a plurality of types of compounds having different elemental compositions, and is configured to include at least two types of layered solid solution compounds. These layered solid solution compounds contain lithium as a carrier that mediates the interelectrode reaction, and at least nickel and manganese as transition metals responsible for the oxidation-reduction reaction. One of the features is that the ratio of the atomic concentration of nickel and the atomic concentration of manganese in the layered solid solution compound is different between the layered solid solution compounds.

  In the present invention, the layered solid solution compound having a high atomic concentration of nickel mainly exhibits low resistance in a region on the high SOC side, that is, a high charge state, and the layered solid solution compound having a low atomic concentration of nickel is mainly composed of a low SOC. This is based on the knowledge that a low resistance is exhibited in the side region, that is, in a low charge state.

  It was confirmed that the layered solid solution compound has a high resistance even in the early stage of discharge, and the resistance increases in a relatively wide range both in the high SOC side region at the beginning of discharge and in the low SOC side region at the end of discharge. In general, in a positive electrode containing a single type of layered solid solution compound, resistance increases in a low SOC side region where the SOC is about 0 to 30% and a high SOC side region where the SOC is about 70% to 100%. There is a tendency that high output cannot be obtained. Therefore, in the positive electrode active material using the layered solid solution compound, the SOC range in which high output can be obtained is limited to a narrow range. Therefore, for example, in an in-vehicle application, in order to obtain a high output, the use is limited to the SOC range having a low resistance. That is, in a secondary battery using a positive electrode active material using a layered solid solution compound, the capacity (effective capacity) that can be practically used is reduced. On the other hand, in the positive electrode active material for a non-aqueous secondary battery according to the present embodiment, by combining layered solid solution compounds having different nickel atomic concentrations, a layered solid solution compound having a relatively high atomic concentration of nickel results in a high SOC. The reduction of the resistance in the region on the low SOC side and the reduction of the resistance in the region on the low SOC side are realized by the layered solid solution compound having a relatively low atomic concentration of nickel.

  The effect of reducing the resistance by combining the layered solid solution compound also depends on the atomic concentration of nickel in the layered solid solution compound to be used, and by combining at least two layered solid solution compounds, the SOC range that is low resistance can be expanded. it can. That is, the region where high output can be obtained is extended to both the high SOC side region and the low SOC side region. The SOC range in which the resistance is reduced can be intentionally manipulated by selecting the nickel concentration in each layered solid solution compound. Therefore, by adjusting the atomic concentration of nickel in each layered solid solution compound, the rechargeable battery can be charged. It is possible to modify the discharge input / output characteristics.

  The effect based on the reduction in resistance caused by the positive electrode active material for a non-aqueous secondary battery according to the present embodiment can be evaluated using as an index the expansion of the practical SOC range and the improvement of the effective capacity.

  In this specification, the practical SOC range means a range of SOC in which low resistance is obtained during discharge and a practically acceptable output is obtained. Specifically, it is defined as a range of SOC having a resistance within a predetermined range with respect to the minimum value of the DC resistance value at the time of discharge as a reference. However, since there is no absolute standard for the practical output required for non-aqueous secondary batteries, it is permissible to define a range below an arbitrary resistance value as the practical SOC range for the minimum value. Is done. As an index for determining the practical SOC range, a range in which the resistance value is not more than twice the minimum resistance value can be exemplified.

  The effective capacity means the discharge capacity in the SOC range where a practically acceptable output can be obtained. The calculation method for the effective capacity is not particularly limited. For example, the value obtained by multiplying the discharge capacity (Ah or its density) at 100% SOC during discharge by the ratio of the practical SOC range is used as an evaluation index. be able to.

The layered solid solution compound is a lithium transition metal composite oxide represented as Li ₂ MnO ₃ —LiM _t O ₂ (M _t represents an element such as Co, Ni, Mn, etc.). The layered solid solution compound is electrochemically inactive but shows a high theoretical capacity, Li ₂ MnO ₃ which is a basic structure of a layered rock-salt structure, and electrochemically active, a layered rock-salt structure is a basic structure LiM _t O ₂ as a solid solution forms primary particles having a layered crystal structure as a main structure. It has the ability to reversibly insert and desorb lithium ions, and in particular, it can desorb not only Li arranged between layers of a layered structure but also Li arranged in a metal layer. Become a substance.

  The positive electrode active material for a non-aqueous secondary battery according to the present embodiment includes a kind of layered solid solution compound (first layered solid solution compound) having a composition containing nickel and manganese as transition metals, and nickel and manganese as transition metals. The first layered solid solution compound has a composition and is configured to contain at least another layered solid solution compound (second layered solid solution compound) having a different ratio of atomic concentration of nickel and atomic concentration of manganese. When the positive electrode active material for a non-aqueous secondary battery includes another layered solid solution compound in addition to the two layered solid solution compounds, the atomic concentration of nickel and the atomic concentration of manganese of these three or more layered solid solution compounds Two types whose ratios are most distant from each other are defined as a first layered solid solution compound and a second layered solid solution compound.

  The ratio between the atomic concentration of nickel and the atomic concentration of manganese in the layered solid solution compound can be measured by a conventionally known method. Specifically, for example, Transmission Electron Microscopy-Energy Dispersive X-ray Spectrometer (TEM-EDX), Transmission Electron Microscopy-Electron Energy Loss Spectroscopy (Transmission Electron Microscopy-Electron Energy) Loss Spectroscopy; TEM-EELS) etc. are used to confirm the atomic concentrations of nickel and manganese, and the ratio between the atomic concentration of nickel and the atomic concentration of manganese is determined from the atomic concentration from which the measurement error in each primary particle is eliminated. The first layered solid solution compound and the second layered solid solution compound can be distinguished.

  The ratio between the atomic concentration of nickel and the atomic concentration of manganese is different. The nickel atom concentration of the layered solid solution compound primary particle having the higher nickel atom concentration is Nir, the manganese atom concentration is Mnr, and the nickel atom concentration is lower. When the nickel concentration is Nip and the manganese atom concentration is Mnp, it means that (Nir / Mnr) / (Nip / Mnp) is 1.1 or more. The first layered solid solution compound and the second layered solid solution compound in which the ratio of the atomic concentration of nickel and the atomic concentration of manganese occupies 10% by mass or more of the total mass of the positive electrode active material in the positive electrode for a non-aqueous secondary battery, respectively. It is preferable.

  Moreover, the positive electrode active material for a non-aqueous secondary battery according to the present embodiment includes at least two layered solid solution compound secondary particles having different average particle sizes, and the average particle size of the two layered solid solution compound secondary particles. Among them, D1 / D2 ≧ 2 when D1 is a large particle diameter and D2 is a small particle diameter. Further, 0.2 ≦ W1 / (W1 + W2) where the mass ratio of the layered solid solution compound secondary particles having an average particle diameter of D1 and the layered solid solution compound secondary particles having an average particle diameter of D2 is W1 and W2, respectively. ≦ 0.9. Filling the space between the layered solid solution compound secondary particles with a large average particle size with the layered solid solution compound secondary particles with a small average particle size by making the average particle size of the two types of layered solid solution compound secondary particles different by 2 times or more And the whole density is increased. Further, when the content of the layered solid solution compound secondary particles having a large average particle size is 20% by mass or more and 90% by mass or less based on the total of the two types of layered solid solution compound secondary particles, the whole is densified and the volume is increased. The hit capacity is improved. In particular, the content of the layered solid solution compound secondary particles having a large average particle diameter is preferably 50% by mass or more and 80% by mass or less because the density becomes higher and the capacity per volume is further improved. In addition, when the positive electrode active material for a non-aqueous secondary battery includes three or more kinds of layered solid solution compound secondary particles having different average particle diameters, the maximum value and the minimum value among the three or more kinds of average particle diameters are set. Are defined as D1 and D2, respectively.

  In the above, the positive electrode active material for a non-aqueous secondary battery includes the first layered solid solution compound and the second layered solid solution compound having different compositions, the layered solid solution compound secondary particles having an average particle diameter of D1, and the average The inclusion of layered solid solution compound secondary particles having a particle diameter of D2 is an independent condition. That is, the positive electrode active material for a non-aqueous secondary battery according to the present embodiment includes at least the forms shown in FIGS. In FIG. 1, the positive electrode active material 100A for a non-aqueous secondary battery comprises a layered solid solution compound primary particle 101A composed of a first layered solid solution compound and a layered solid solution compound primary particle 102A composed of a second layered solid solution compound. And the positive electrode active material 100A for a non-aqueous secondary battery includes a layered solid solution compound secondary particle 110A having an average particle diameter of D1 and a layered solid solution compound secondary particle 120A having an average particle diameter of D2, The layered solid solution compound secondary particles 110A and 120A include both the layered solid solution compound primary particle 101A composed of the first layered solid solution compound and the layered solid solution compound primary particle 102A composed of the second layered solid solution compound. . In FIG. 2, the positive electrode active material 100B for a non-aqueous secondary battery is composed of a layered solid solution compound primary particle 101B composed of a first layered solid solution compound and a layered solid solution compound primary particle composed of a second layered solid solution compound. 102B, and a layered solid solution compound secondary particle 110B having an average particle diameter of D1 and a layered solid solution compound secondary particle 120B having an average particle diameter of D2, and the layered solid solution compound secondary particles 110B therein are first layers. Including both a layered solid solution compound primary particle 101B composed of one layered solid solution compound and a layered solid solution compound primary particle 102B composed of a second layered solid solution compound, and the layered solid solution compound secondary particle 120B is a second layered solid solution It is comprised only from the layered solid solution compound primary particle 102B comprised from a compound.

  In FIG. 3, the positive electrode active material 100C for a non-aqueous secondary battery is composed of a layered solid solution compound primary particle 101C composed of a first layered solid solution compound and a layered solid solution compound primary particle composed of a second layered solid solution compound. And a layered solid solution compound secondary particle 110C having an average particle diameter of D1 and a layered solid solution compound secondary particle 120C having an average particle diameter of D2, of which the layered solid solution compound secondary particle 120C Including both a layered solid solution compound primary particle 101C composed of one layered solid solution compound and a layered solid solution compound primary particle 102C composed of a second layered solid solution compound, and the layered solid solution compound secondary particle 110C is a first layered solid solution It is comprised only from the layered solid solution compound primary particle 101C comprised from a compound. Moreover, in FIG. 4, the positive electrode active material 100D for non-aqueous secondary batteries is a layered solid solution compound primary particle composed of a layered solid solution compound primary particle 101D composed of a first layered solid solution compound and a second layered solid solution compound. The layered solid solution compound secondary particles 110D having an average particle diameter of D1 and the layered solid solution compound secondary particles 120D having an average particle diameter of D2, and the layered solid solution compound secondary particles 110D include: The layered solid solution compound primary particles 101D composed of the layered solid solution compound and the layered solid solution compound primary particles 102D composed of the second layered solid solution compound are composed of only one, and the layered solid solution compound secondary particles 120D are the second The layered solid solution compound is composed only of the layered solid solution compound primary particles 102D.

  Moreover, in FIG. 5, the positive electrode active material 100E for non-aqueous secondary batteries is a layered solid solution compound primary particle composed of a layered solid solution compound primary particle 101E composed of a first layered solid solution compound and a second layered solid solution compound. The layered solid solution compound secondary particles 110E including the layered solid solution compound secondary particles 110E including 102E and having an average particle diameter of D1 and the layered solid solution compound secondary particles 120E including the average particle diameter of D2 include: The layered solid solution compound primary particles 101E composed of the layered solid solution compound and the layered solid solution compound primary particles 102E composed of the second layered solid solution compound are composed of only one, and the layered solid solution compound secondary particles 110E are the first The layered solid solution compound is composed of only the layered solid solution compound primary particles 101E. 6, as in FIG. 1, the positive electrode active material 100 </ b> F for the non-aqueous secondary battery includes the layered solid solution compound secondary particles 110 </ b> F having an average particle diameter of D <b> 1 and the layered solid solution having an average particle diameter of D <b> 2. In addition to the compound secondary particles 120F, the layered solid solution compound secondary particles 110F and 120F are respectively composed of the layered solid solution compound primary particles 101F and 101F ′ composed of the first layered solid solution compound and the second layered solid solution compound. Layered solid solution compound primary particles 102F and 102F ′. Further, in the embodiment of FIG. 7, the positive electrode active material 100G for non-aqueous secondary batteries includes a layered solid solution compound secondary particle 110G having an average particle diameter of D1 and a layered solid solution compound secondary particle 120G having an average particle diameter of D2. In addition, the layered solid solution compound secondary particle 110G having an average particle diameter of D1 is composed of the layered solid solution compound primary particles 101G and 101G ′ composed of the first layered solid solution compound and the second layered solid solution compound. The layered solid solution compound secondary particles 120G including the layered solid solution compound primary particles 102G and 102G ′ and having an average particle diameter of D2 are layered solid solution compound primary particles 101G ″ and 101G ″ composed of the first layered solid solution compound. And primary layered particles 102G ″, 102G ′ ″ composed of the second layered solid solution compound.

  Furthermore, in FIG. 8, the positive electrode active material 100H for a non-aqueous secondary battery is a layered solid solution compound primary particle composed of a layered solid solution compound primary particle 101H composed of a first layered solid solution compound and a second layered solid solution compound. The layered solid solution compound secondary particles 110H composed only of the layered solid solution compound primary particles 101H composed of the first layered solid solution compound containing 102H and having an average particle size of D1, and the average particle size of D2. And a layered solid solution compound secondary particle 120H composed only of the layered solid solution compound primary particle 102H made of the second layered solid solution compound.

  In particular, the form shown in FIG. 8 is preferable. That is, the layered solid solution compound composed of the layered solid solution compound primary particle 110H composed of the layered solid solution compound primary particle 101H composed of the first layered solid solution compound and the layered solid solution compound primary particle 102H composed of the second layered solid solution compound. When the average particle diameter of the secondary particle 120H is D3 and D4, respectively, D3 / D4 ≧ 2, and the mass ratio of the layered solid solution compound secondary particle 110H and the layered solid solution compound secondary particle 120H is W3 and W4, respectively. Sometimes 0.2 ≦ W3 / (W3 + W4) ≦ 0.9, particularly preferably 0.5 ≦ W3 / (W3 + W4) ≦ 0.8. Thereby, a positive electrode active material is densified and the effective capacity per volume improves. Moreover, it is preferable because it is a layered solid solution compound having the same composition and it is not necessary to produce a plurality of secondary particles having different particle diameters and can be produced at low cost.

  The average particle diameter of each secondary particle in the layered solid solution compound composite is preferably 1 μm or more and 60 μm or less, but is not limited thereto. By setting the average particle diameter of the secondary particles to 60 μm or less, a positive electrode having no irregularities can be produced. Moreover, by setting the average particle diameter of the secondary particles to 1 μm or more, a positive electrode mixture slurry having a high solid content ratio can be manufactured, and a high-density positive electrode can be manufactured.

  Further, in the positive electrode active material for a non-aqueous secondary battery according to the present embodiment, each layered solid solution compound secondary particle includes at least two kinds of layered solid solution compound primary particles having different average particle sizes, and these two kinds of layered solid solution compounds Layered solid solution compound primary particles and average particles in which d1 / d2 ≧ 2 when the large particle size is d1 and the small particle size is d2 out of the average particle size of the solid solution compound primary particles, and the average particle size is d1 It is preferable that 0.2 ≦ w1 / (w1 + w2) ≦ 0.9 when the mass ratio of the layered solid solution compound primary particles having a diameter d2 is w1 and w2, respectively. An example of this is shown in FIG. In the positive electrode active material 100G for a non-aqueous secondary battery in FIG. 7, the layered solid solution compound secondary particle 110G having an average particle diameter of D1 is combined with the layered solid solution compound primary particles 101G and 102G having an average particle diameter of d1 and the average particle diameter. Is composed of layered solid solution compound primary particles 101G ′ and 102G ′ in which d2 is d2. Further, for the layered solid solution compound secondary particles 120G having an average particle diameter of D2, the layered solid solution compounds 101G '' and 102G '' having an average particle diameter of d1 'and a layered solid solution having an average particle diameter of d2' are also used. It is composed of compound primary particles 101G ′ ″ and 102G ′ ″. By making the average particle diameter of the two kinds of layered solid solution compound primary particles different by 2 times or more, the space between the layered solid solution compound primary particles having a large average particle diameter can be filled with the layered solid solution compound primary particles having a small average particle diameter, The layered solid solution compound secondary particles are densified. Further, the content of the primary particles of the layered solid solution compound having a large average particle diameter is 20% by mass or more and 90% by mass or less with respect to the total of the two types of layered solid solution compound primary particles, whereby the layered solid solution compound secondary particles have a high density. And the capacity per volume is improved. In particular, the content of the primary particles of the layered solid solution compound having a large average particle diameter is preferably 50% by mass or more and 80% by mass or less because the density becomes higher and the capacity per volume is further improved. When the layered solid solution compound secondary particles include three or more kinds of layered solid solution compound primary particles having different average particle diameters, the maximum value and the minimum value of the three or more kinds of average particle diameters are respectively expressed as d1 ( Or d1 ′ (hereinafter the same) and d2 (or d2 ′, the same).

  Each of the layered solid solution compound primary particles having an average particle diameter of d1 and the layered solid solution compound primary particles having an average particle diameter of d2 is composed of one of the first layered solid solution compound and the second layered solid solution compound. It may be configured to include both of them. That is, the layered solid solution compound secondary particles include at least two layered solid solution compound primary particles having different average particle diameters, and the positive electrode active material for a non-aqueous secondary battery as a whole includes the first layered solid solution compound and the second layered solid solution compound. The inclusion of the layered solid solution compound is an independent condition. And among each form, as shown in FIG. 6, the layered solid solution compound secondary particle 110F is composed of the layered solid solution compound primary particle 101F composed of the first layered solid solution compound and the second layered solid solution compound. Layered solid solution compound primary particles 102F, and the average particle sizes of the layered solid solution compound primary particles 101F composed of the first layered solid solution compound 101F and the layered solid solution compound primary particles 102F composed of the second layered solid solution compound, respectively. When d3 and d4, d3 / d4 ≧ 2, and the mass of the layered solid solution compound primary particle 101F composed of the first layered solid solution compound and the layered solid solution compound primary particle 102F composed of the second layered solid solution compound It is preferable that 0.2 ≦ w3 / (w3 + w4) ≦ 0.9 when the ratio is w3 and w4, respectively. And particularly preferably 0.5 ≦ w3 / (w3 + w4) ≦ 0.8. Thereby, the expansion of the practical SOC range based on the difference in the ratio between the atomic concentration of nickel and the atomic concentration of manganese can be reliably achieved, and the layered solid solution compound secondary particles are densified, and the effective capacity per volume is increased. improves. Moreover, it is preferable because it is a layered solid solution compound having the same composition and it is not necessary to produce a plurality of primary particles having different particle diameters, and it can be produced at low cost.

  The average particle diameter of each primary particle of the layered solid solution compound is preferably 30 nm or more and 700 nm or less, but is not limited thereto. By setting the average particle diameter of the primary particles to 700 nm or less, the specific surface area of the primary particles is ensured, so that the resistance can be significantly reduced. The average particle diameter of the primary particles is preferably 30 nm or more because the filling rate of the layered solid solution compound primary particles contained in the layered solid solution compound secondary particles is secured.

  The average particle diameter of the layered solid solution compound secondary particles or the layered solid solution compound primary particles should be measured based on observation with a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Can do. By observation, a group of at least two types of layered solid solution compound secondary particles or layered solid solution compound primary particles having significantly different particle sizes is discriminated, and 40 particles are extracted in order of the particle size from the median for each group. Then, the average particle diameter is obtained by calculating a weighted average of these particle diameters. In addition, a particle diameter can be calculated | required as an average value of the long diameter and short diameter of a particle | grain in the observed electron microscope image. The mass ratio is proportional to the area ratio occupied in the electron microscopic image, and can be calculated by the area ratio occupied by each layered solid solution compound secondary particle or each layered solid solution compound primary particle. If the ratio of the atomic concentration of nickel to the atomic concentration of manganese in the two or more types of layered solid solution compound secondary particles or layered solid solution compound primary particles having different average particle sizes is the same (in the case of the same composition), the entire particle If the value of D20 and D60 is D20 ≦ D60 / 2, the particle size distribution is usually within the scope of the present invention.

Specifically, each of the layered solid solution compounds has the following general formula (1):
_{xLi 2 MnO 3 - (1-} x) LiNi a Mn b Co c M d O 2 (1)
[Wherein, x, a, b, c, d are the following relationships: 0.2 ≦ x ≦ 0.8, 0.3 ≦ a <1.0, 0 ≦ b ≦ 0.6, 0 ≦ c. <0.5, 0 ≦ d ≦ 0.05 is satisfied, and M is a group consisting of Fe, Ti, Zr, Al, Mg, Cr, V, Nb, Ta, W, Mo, Cu, Zn, Sn, and Ru. It is at least one element selected from more. It is preferable to have a composition represented by

In the general formula (1), x represents the ratio of Li ₂ MnO ₃ in the layered solid solution compound. The higher the ratio of Li ₂ MnO _3, the higher the capacity because the layered solid solution compound becomes excessive in lithium. On the other hand, the higher the ratio of Li ₂ MnO _3, the lower the electrochemical activity, so that the resistance of the layered solid solution compound increases. A composition in which x is 0.2 or more and 0.8 or less is preferable because lithium can be enriched to a certain extent to increase the capacity and a decrease in output and capacity due to an increase in resistance can be avoided.

  Ni is generally an element that has a large change in valence and is effective in improving the capacity density, and is cheaper and easier to obtain than Co. Therefore, by setting a to a composition of 0.3 or more and less than 1.0, it is possible to advantageously achieve the expansion of the practical SOC range and the increase of the effective capacity.

  Although Mn is inferior in the effect of improving the capacity density as compared with Ni, it is an inexpensive and easily available element. Therefore, by setting b to a composition of more than 0 and not more than 0.6, the raw material cost of the layered solid solution compound can be suppressed while securing a certain level of atomic concentration of Ni. In addition, it is good also as a layered solid solution compound with few Mn as a composition whose b is 0.

  Co contributes to an increase in capacity density but is expensive. In addition, a layered solid solution compound containing a large amount of Co tends to cause cation mixing and tends to have a decreased crystallinity. As a result, it is difficult to reduce the resistance on the high SOC side. Therefore, on the high SOC side, it is preferable to use a layered solid solution compound containing an atomic concentration of Ni of a predetermined ratio or more. Therefore, by setting c to a composition exceeding 0 and less than 0.5, it is possible to obtain a high-capacity layered solid solution compound while ensuring a certain level of Ni atomic concentration. The composition in which c is 0 may be a layered solid solution compound containing no Co.

  In the general formula (1), d represents the composition ratio of the additive element (M) in the layered solid solution compound. The element of M is at least one element selected from the group consisting of Fe, Ti, Zr, Al, Mg, Cr, V, Nb, Ta, W, Mo, Cu, Zn, Sn, and Ru, By substituting these elements with Ni, Mn or Co, effects such as stabilization of the crystal structure and charge compensation can be obtained. Therefore, by setting the composition of d to more than 0 and not more than 0.05, the capacity can be increased and the thermal stability can be improved. The layered solid solution containing no element of M as the composition of d = 0. It may be a compound.

  In the general formula (1), the relationship among Ni, Mn, Co, and M elements substantially satisfies a + b + c + d = 1. Further, the composition of the layered solid solution compound is not limited to strictly following the stoichiometric ratio, and the composition may be non-stoichiometric without departing from the gist of the present invention. You may have. However, the average valence (oxidation number) of Ni, Mn, Co and M elements is preferably 3.2 or more.

  In the layered solid solution compound, the atomic concentration of nickel is preferably 2.4 mol% or more, more preferably 2.4 mol% or more and 12.6 mol% or less, and more preferably 2.4 mol% or more and 9.5 mol% or less. More preferably it is. That is, for each of the layered solid solution compounds included in the positive electrode active material for a non-aqueous secondary battery according to this embodiment, adjustment is made so that the atomic concentration of nickel is different within this atomic concentration range. Is preferred. The atomic concentration of nickel corresponds to the number of nickel atoms relative to the total number of atoms of lithium, nickel, manganese, cobalt, M, and oxygen in the layered solid solution compound.

  By setting the atomic concentration of nickel to 2.4 mol% or more, the effect of reducing the resistance by nickel can be obtained in a significant and good degree. If the atomic concentration of nickel is 12.6 mol% or less, preferably 9.5 mol% or less, a layered solid solution compound having a stable crystal structure can be obtained, and a high capacity can be obtained.

The ratio of the atomic concentration of nickel to the atomic concentration of manganese in the layered solid solution compound is the ratio of the atomic concentration of nickel to the atomic concentration of manganese in the layered solid solution compound having a high nickel atomic concentration (atomic concentration of nickel / atomic concentration of manganese). C ₁ , where the ratio of the atomic concentration of nickel to the atomic concentration of manganese in the layered solid solution compound having a low atomic concentration of nickel (nickel atomic concentration / manganese atomic concentration) is C ₂ , C ₁ > C ₂ , and It is preferable that the range is 1.3 ≦ C ₁ / C ₂ ≦ 7.0.

By setting the atomic concentration ratio C ₁ / C ₂ to 1.3 or more, there is a significant difference in the ratio between the atomic concentration of nickel and the atomic concentration of manganese in each layered solid solution compound. Thus, the effective capacity can be improved. Further, by setting the atomic concentration ratio C ₁ / C ₂ to 7.0 or less, the resistance can be reduced in a balanced manner in both the high SOC region and the low SOC region, and the practical SOC range is expanded. Thus, the effective capacity can be improved. On the other hand, if the atomic concentration ratio C ₁ / C ₂ exceeds 7.0, the ratio of the atomic concentration of nickel in each layered solid solution compound becomes excessive or excessive. When C ₁ / C ₂ is in the range of 1.3 ≦ C ₁ / C ₂ ≦ 7.0, the practical SOC range can be greatly expanded.

The positive electrode active material for a non-aqueous secondary battery according to this embodiment may contain other positive electrode active material species together with the first layered solid solution compound and the second layered solid solution compound. As other positive electrode active material species to be contained, other layered solid solution compounds satisfying the elemental composition of the general formula (1) and having different nickel atomic concentrations from the first layered solid solution compound and the second layered solid solution compound (first type) No. 3 layered solid solution compound) and general positive electrode active material species conventionally used for positive electrodes of lithium ion secondary batteries. At this time, it is preferable that the nickel atomic concentration, the total mass, the particle diameter, and the like of the third layered solid solution compound are the same as those of the first layered solid solution compound and the second layered solid solution compound. By containing the third layered solid solution compound, the charge / discharge input / output characteristics of the secondary battery can be adjusted. Common cathode active species, for example, or layered oxide compound represented as LiM3O _2, polyanionic compounds such as represented as LiM4A _p O _q and the like. In the above formula, M3 and M4 are at least one element selected from the group consisting of Mn, Ni, Co, and Fe, and A is bonded to oxygen to form PO ₄ , SiO ₄ , BO _3. And p and q are numbers satisfying 1 ≦ p ≦ 2, 3 ≦ q ≦ 7. Part of the elements M3 and M4 may be substituted with elements such as Ti, Zr, Al, Mg, Cr, V, Nb, Ta, W, and Mo.

  By using such other positive electrode active material species in combination, characteristics according to the species can be imparted to the positive electrode for a non-aqueous secondary battery. For example, when the third layered solid solution compound is used in combination, it is possible to control the discharge output characteristics such as making the discharge voltage constant in a wider SOC range.

  The elemental composition of each positive electrode active material species is, for example, Transmission Electron Microscopy-Energy Dispersive X-ray Detector (TEM-EDX) or Transmission Electron Microscope-Electron Energy Loss Spectroscopy ( This can be confirmed by Transmission Electron Microscopy-Electron Energy Loss Spectroscopy (TEM-EELS).

  Each compound such as a layered solid solution compound contained in the positive electrode active material for a non-aqueous secondary battery according to the present embodiment can be manufactured according to a general method for manufacturing a positive electrode active material. Examples of such a production method include a solid phase method, a coprecipitation method, a sol-gel method, and a hydrothermal method, but a method that does not involve dissolution of raw materials is preferable, and a solid phase method is particularly preferable. . Here, the dissolution of the raw material means that the dissolution rate of the raw material is 10% or more. The dissolution rate of the raw material is defined as the mass of the dissolved material / the mass of the raw material × 100 (%). By producing the positive electrode active material using a method that does not involve melting of the raw material, the formation of a heterogeneous phase can be suppressed.

  In the production of the positive electrode active material using the solid phase method, first, raw material Li-containing compound, Ni-containing compound, Mn-containing compound, etc. are weighed at a ratio of a predetermined element composition, and pulverized and mixed to prepare a raw material powder. To do.

  As the Li-containing compound, for example, lithium acetate, lithium nitrate, lithium carbonate, lithium hydroxide, lithium chloride, lithium sulfate and the like can be used. Examples of the Ni-containing compound include nickel acetate, nickel nitrate, nickel carbonate, nickel sulfate, and nickel hydroxide. Examples of the Mn-containing compound include manganese acetate, manganese nitrate, manganese carbonate, and sulfuric acid. Manganese, manganese oxide, manganese hydroxide, or the like can be used. In addition, when an element of Co or M is contained, these acetates, nitrates, carbonates, sulfates, hydroxides, oxides, and the like can be used.

  For the pulverization and mixing in preparing the raw material powder, either dry pulverization or wet pulverization can be used. As the pulverizing means, for example, a pulverizer such as a ball mill, a bead mill, a planetary ball mill, an attritor, or a jet mill can be used.

  The prepared raw material powder is fired to form primary particles of the positive electrode active material. It is preferable to sinter the raw material powder by subjecting the raw material compound to thermal decomposition by calcination under an inert gas atmosphere or an oxidizing gas atmosphere, pulverizing and classifying appropriately, and then performing main calcination. The heating temperature in the preliminary firing is, for example, about 300 ° C. to 600 ° C., and the heating temperature in the main firing is, for example, 700 ° C. to 1100 ° C.

  The positive electrode active material can be produced by crushing or pulverizing / mixing primary particles of the produced positive electrode active material and granulating secondary particles by dry granulation or wet granulation. The positive electrode active material is an aggregate of manufactured secondary particles. As the granulating means, for example, a granulator such as a spray dryer can be used. Moreover, you may perform a baking process after granulation.

  The positive electrode active material for a non-aqueous secondary battery manufactured as described above is used as a material for a positive electrode for a non-aqueous secondary battery.

  The positive electrode for a non-aqueous secondary battery according to this embodiment is mainly coated with a positive electrode mixture layer including a positive electrode active material for a non-aqueous secondary battery, a conductive material, and a binder, and a positive electrode mixture layer. A positive electrode current collector.

  As the conductive material, a conductive material used in a general lithium ion secondary battery can be used. Specific examples include carbon particles such as graphite powder, acetylene black, furnace black, thermal black, and channel black, carbon fibers, and the like. What is necessary is just to use the quantity which becomes about 1 mass% or more and about 10 mass% or less with respect to the mass of the whole positive electrode compound material layer, for example.

  As the binder, a binder used in a general lithium ion secondary battery can be used. Specific examples include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyhexafluoropropylene, styrene-butadiene rubber, carboxymethyl cellulose, polyacrylonitrile, and modified polyacrylonitrile. What is necessary is just to use the quantity used as a binder about 1 mass% or more and 10 mass% or less with respect to the mass of the whole positive mix layer, for example.

  As the positive electrode current collector, foil made of aluminum or aluminum alloy, expanded metal, punching metal, or the like can be used. The foil may have a thickness of, for example, about 8 μm to 30 μm.

  The positive electrode for a non-aqueous secondary battery according to this embodiment can be manufactured according to a general positive electrode manufacturing method using the positive electrode active material for a non-aqueous secondary battery.

  An example of a method for producing a positive electrode for a non-aqueous secondary battery includes a positive electrode mixture preparation step, a positive electrode mixture coating step, and a molding step. In the positive electrode mixture preparation step, a positive electrode active material, a conductive material, and a binder are mixed in a solvent to prepare a slurry-like positive electrode mixture. At least the positive electrode active material is used and stirred and homogenized together with the conductive material in a solvent in which the binder is dissolved. Depending on the type of binder, N-methylpyrrolidone, water, N, N-dimethylformamide, N, N-dimethylacetamide, methanol, ethanol, propanol, isopropanol, ethylene glycol, diethylene glycol, glycerin, dimethyl It can be selected from sulfoxide, tetrahydrofuran and the like. Examples of the stirring means for mixing the materials include a planetary mixer, a disper mixer, and a rotation / revolution mixer.

  In the positive electrode mixture coating step, the prepared slurry-like positive electrode mixture is applied onto the positive electrode current collector, and then the solvent is dried by heat treatment to form the positive electrode mixture layer. Examples of the coating means for applying the positive electrode mixture include a bar coater, a doctor blade, and a roll transfer machine.

  In the molding step, the dried positive electrode mixture layer is pressure-molded using a roll press or the like, and cut with a positive electrode current collector as necessary to obtain a positive electrode for a non-aqueous secondary battery having a desired shape. . The thickness of the positive electrode mixture layer formed on the positive electrode current collector may be, for example, about 50 μm to 300 μm.

  The positive electrode for a non-aqueous secondary battery manufactured as described above is used as a material for a non-aqueous secondary battery.

  The non-aqueous secondary battery according to the present embodiment mainly includes a positive electrode for a non-aqueous secondary battery, a negative electrode for a non-aqueous secondary battery, a separator, and a non-aqueous electrolyte, which are cylindrical, rectangular, and button type It is configured to be accommodated in an outer package of a shape such as a laminate sheet type.

FIG. 9 is a schematic cross-sectional view showing an example of the non-aqueous secondary battery according to this embodiment.
FIG. 9 illustrates a cylindrical non-aqueous secondary battery. The non-aqueous secondary battery 1 includes a positive electrode 2 in which a positive electrode mixture is coated on both surfaces of a positive electrode current collector, and a negative electrode current collector. The electrode group which consists of the negative electrode 3 by which the negative electrode compound material was coated on both surfaces of this, and the separator 4 interposed between the positive electrode 2 and the negative electrode 3 is provided. The positive electrode 2 and the negative electrode 3 are wound through a separator 4 and accommodated in a cylindrical battery can 5. The positive electrode 2 is electrically connected to the sealing lid 8 via the positive electrode lead piece 6, and the negative electrode 3 is electrically connected to the battery can 5 via the negative electrode lead piece 7, and the positive electrode lead piece 6 and the negative electrode 3. Between the negative electrode lead piece 7 and the positive electrode 2, an insulating plate 10 made of an epoxy resin or the like is disposed to be electrically insulated. Each lead piece is a current drawing member made of the same material as each current collector, and is joined to each current collector by spot welding or ultrasonic welding. The battery can 5 has a structure in which a non-aqueous electrolyte is injected into the battery can 5 and then sealed with a sealing material 9 such as rubber and the top is sealed with a sealing lid 8.

  The negative electrode for a non-aqueous secondary battery can be composed of a negative electrode mixture layer containing a negative electrode active material used in a general lithium ion secondary battery and a negative electrode current collector.

  As the negative electrode active material, for example, one or more selected from a carbon material, a metal material, a metal oxide material, and the like can be used. Examples of the carbon material include graphites such as natural graphite and artificial graphite, carbides such as coke and pitch, amorphous carbon, and carbon fibers. In addition, examples of the metal material include lithium, silicon, tin, aluminum, indium, gallium, magnesium, and alloys thereof, and examples of the metal oxide material include metal oxides including tin, silicon, and the like. As the negative electrode for a non-aqueous secondary battery, a material selected from the same group as the binder and the conductive material used in the positive electrode for a non-aqueous secondary battery may be used as necessary. What is necessary is just to use the quantity used as a binder about 5 mass% with respect to the mass of the whole negative electrode compound material, for example.

  As the negative electrode current collector, copper or nickel foil, expanded metal, punching metal, or the like can be used. The foil may have a thickness of about 5 μm to 20 μm, for example.

  A negative electrode for a non-aqueous secondary battery is coated with a negative electrode mixture obtained by mixing a negative electrode active material and a binder on a negative electrode current collector and pressure-molded, as with a positive electrode for a non-aqueous secondary battery. It can manufacture by cutting according to. The thickness of the negative electrode mixture layer formed on the negative electrode current collector may be, for example, about 20 μm to 150 μm.

  As the separator, a polyolefin resin such as polyethylene, polypropylene, and a polyethylene-polypropylene copolymer, a microporous film such as a polyamide resin and an aramid resin, a nonwoven fabric, and the like can be used.

Non-aqueous electrolytes include LiClO ₄ , LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiCF ₃ CO ₂ , Li ₂ C ₂ F ₄ (SO ₃ ) _2. A solution in which a lithium salt such as LiN (CF ₃ SO ₂ ) ₂ or LiC (CF ₃ SO ₂ ) ₃ is dissolved in a non-aqueous solvent can be used. The concentration of the lithium salt in the non-aqueous electrolyte is preferably 0.7M or more and 1.5M or less.

  As the non-aqueous solvent, diethyl carbonate, dimethyl carbonate, ethylene carbonate, propylene carbonate, vinylene carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl acetate, dimethoxyethane and the like can be used. In addition, various additives should be added to the non-aqueous electrolyte for the purpose of suppressing oxidative decomposition and reductive decomposition of the electrolytic solution, preventing precipitation of metal elements, improving ion conductivity, and improving flame retardancy. Can do. Examples of such additives include 1,3-propane sultone and 1,4-butane sultone that suppress decomposition of the electrolytic solution, insoluble polyadipic anhydride that improves the storage stability of the electrolytic solution, and hexahydrophthalic anhydride. Examples include acids and the like, and fluorine-substituted alkylborons that improve flame retardancy.

  Non-aqueous secondary batteries according to the present embodiment having the above configuration are, for example, small power sources such as portable electronic devices and household electric devices, stationary power sources such as uninterruptible power sources and power leveling devices, ships, railways, It can be used as a drive power source for hybrid vehicles, electric vehicles, and the like.

  The in-vehicle non-aqueous secondary battery module according to this embodiment is a secondary battery module suitable as an in-vehicle drive power source for hybrid vehicles, electric vehicles, etc., and mainly includes the non-aqueous secondary battery and the controller. And a fuse and a balance circuit. In a non-aqueous secondary battery module for in-vehicle use, a plurality of non-aqueous secondary batteries are connected in series to form a battery group in order to secure a desired output, and these battery groups are combined in parallel to form a casing. A stored and high capacity battery module is formed.

  The fuse has a protection function against overcurrent, and the balance circuit has a function of leveling the voltage between the electrodes. The controller has a function to monitor the voltage, current, and temperature between the electrodes of the non-aqueous secondary battery, and a function to prevent overcharge and overdischarge in the range of the set charge / discharge end potential by the protection circuit. ing. The controller is connected to signal input / output means for communicating with the outside, and the signal input / output means inputs, for example, a control signal from an ECU provided in the vehicle and outputs battery monitoring information to the ECU. Has the function to perform. As a configuration of the secondary battery module, in addition to these, a capacity monitoring function, a leveling function, a cooling function, and the like of each secondary battery may be further provided.

  The vehicle-mounted non-aqueous secondary battery module according to the present embodiment includes a non-aqueous secondary battery having a wide SOC range in which a predetermined output can be obtained. Regardless of the cruising distance of the vehicle after charging, it is possible to output stably, and in a hybrid vehicle or the like, it is useful in that the internal combustion engine can be assisted in any charged state. Moreover, since the in-vehicle non-aqueous secondary battery module according to the present embodiment has an excellent effective capacity, it is possible to reduce the module size with respect to the required capacity.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, the technical scope of this invention is not limited to this.

  A nonaqueous secondary battery including a positive electrode containing a positive electrode active material containing a plurality of kinds of layered solid solution compounds having different atomic concentration ratios of nickel and manganese was manufactured, and its effective capacity was evaluated.

First, a layered solid solution compound primary particle A composed of a layered solid solution compound having a low ratio of nickel atomic concentration to manganese atomic concentration (nickel atomic concentration / manganese atomic concentration) and the layered solid solution compound primary particle A The layered solid solution compound secondary particles 1 were produced.
The raw material lithium carbonate, manganese carbonate, and nickel carbonate were weighed so as to have a predetermined element composition ratio, added to a zirconia pot, further added with acetone, and ground and mixed without being dissolved in a planetary ball mill. And the obtained slurry was dried and raw material powder was obtained. Subsequently, the obtained raw material powder was calcined at 500 ° C. for 12 hours in the air, then added to a zirconia pot, further added with acetone, and pulverized and mixed without dissolving in a planetary ball mill. And after drying the obtained slurry, it baked at 1000 degreeC for 12 hours in air | atmosphere, and pulverized with the bead mill, and the layered solid solution compound primary particle A was obtained. The obtained layered solid solution compound primary particles A are spray-dried by a four-fluid nozzle type spray dryer to granulate the secondary particles, and the granulated body is calcined at 650 ° C. for 5 hours in the atmosphere to form layered solid solution compound secondary particles. 1 was obtained. The elemental composition of the layered solid solution compound constituting the layered solid solution compound primary particle A is Li _1.16 Ni _0.2 Mn _0.6 O ₂ (0.45Li ₂ MnO ₃ -0.55LiNi _0.45 Mn _0.55 O ₂ ), and the average particle size of the layered solid solution compound primary particles A was 0.17 μm. Moreover, the average particle diameter of the layered solid solution compound secondary particles 1 was 4 μm. The atomic concentration of nickel in the layered solid solution compound constituting the layered solid solution compound primary particle A was 5.1 mol%.

  Subsequently, a layered solid solution compound primary particle B composed of a layered solid solution compound having a high ratio of nickel atomic concentration and manganese atomic concentration, and a layered solid solution compound secondary particle 2 composed of the layered solid solution compound primary particle B. Manufactured.

The layered solid solution compound primary particles B were obtained in the same manner as the layered solid solution compound primary particles A except that the ratio of the raw materials was changed. The layered solid solution compound secondary particles 2 were obtained in the same manner as the layered solid solution compound secondary particles 1 except that a rotary atomizer type spray dryer was used. The elemental composition of the layered solid solution compound constituting the obtained layered solid solution compound primary particle B was Li _1.16 Ni _0.3 Mn _0.5 O ₂ (0.45Li ₂ MnO ₃ -0.55LiNi _0.68 Mn _{0 .32} O ₂ ) and the average particle diameter of the layered solid solution compound primary particles B was 0.45 μm. The average particle size of the layered solid solution compound secondary particles 2 was 30 μm. The atomic concentration of nickel in the layered solid solution compound constituting the layered solid solution compound primary particle B was 7.6 mol%.

  Next, layered solid solution compound secondary particles 3 and 4 were produced. The layered solid solution compound primary particles A and the layered solid solution compound primary particles B were mixed so as to have a mass ratio of 0.2: 0.8, pure water was added, and spray drying was performed with a spray dryer to granulate the secondary particles. . As the layered solid solution compound secondary particles 3, a four-fluid nozzle spray dryer was used. As the layered solid solution compound secondary particles 4, a rotary atomizer type spray dryer was used. The average particle diameters of the layered solid solution compound secondary particles 3 and 4 were 4 μm and 30 μm, respectively.

Next, the ratio of the raw materials was changed to produce layered solid solution compound primary particles C, which is an intermediate composition between the layered solid solution compound primary particles A and the layered solid solution compound primary particles B. The elemental composition of the layered solid solution compound constituting the obtained layered solid solution compound primary particles C was Li _1.16 Ni _0.25 Mn _0.55 O ₂ (0.45Li ₂ MnO ₃ -0.55LiNi _0.57 Mn _{0 .43} O ₂ ), and the average particle diameter of the layered solid solution compound primary particles C was 0.47 μm. Pure water was added to the primary particles C of the layered solid solution compound, and secondary particles were granulated by spray drying with a spray dryer. The obtained granulated body was fired at 650 ° C. for 5 hours in the air to obtain layered solid solution compound secondary particles 5. In addition, the average particle diameter of the obtained layered solid solution compound secondary particles 5 was 4 μm. The atomic concentration of nickel in the layered solid solution compound constituting the layered solid solution compound primary particle C was 6.3 mol%.

(Example 1)
The obtained layered solid solution compound secondary particles 1 and layered solid solution compound secondary particles 2 were mixed at a mass ratio of 0.8: 0.2 to obtain a positive electrode active material. In addition, the ratio ( _{C1-1 / C1-2} ) of the atomic concentration of nickel ( _C1-1 ) and the atomic concentration of manganese ( _C1-2 ) in the layered solid solution compound constituting the layered solid solution compound primary particle B is determined. The ratio of the atomic concentration of nickel (C _2-1 ) to the atomic concentration of manganese (C _2-2 ) in the layered solid solution compound constituting the primary particle A of the layered solid solution compound C ₁ (C _{2-1 /} C _2-2 ) when was the _{C 2,} the values of C 1 / _{C 2} was 1.8.

(Examples 2-6, Comparative Examples 1 and 2)
Next, a positive electrode active material was produced in the same manner as in Example 1 except that the mixing ratio of the layered solid solution compound secondary particles 1 and the layered solid solution compound secondary particles 2 was changed. Table 1 below shows the mixing ratio (mass ratio) of the secondary particles of the layered solid solution compound used. In Table 3, the mass ratio of the layered solid solution compound secondary particles 1 is W2, the average particle diameter is D2, the mass ratio of the layered solid solution compound secondary particles 2 is W1, and the average particle diameter is D1.

(Example 7)
The layered solid solution compound secondary particles 3 and the layered solid solution compound secondary particles 4 were mixed at a mass ratio of 0.2: 0.8 to produce a positive electrode active material. The positive electrode active material includes two types of layered solid solution compound secondary particles having different average particle sizes, and each layered solid solution compound secondary particle includes two types of layered solid solution compound primary particles having different average particle sizes. It is out.

(Comparative Example 3)
A positive electrode active material composed of an aggregate of only the layered solid solution compound secondary particles 5 was produced. This positive electrode active material has the same metal component ratio as in Example 2.

  Manufacture of the non-aqueous secondary battery using the positive electrode active material which concerns on Examples 1-7 and Comparative Examples 1-3 was performed in the following procedure, respectively.

  First, 95 parts by mass of a positive electrode active material, 3 parts by mass of a conductive material, and 2 parts by mass of a binder were mixed with N-methylpyrrolidone as a solvent and homogenized to prepare a slurry-like positive electrode mixture. As the conductive material, acetylene black “DENKA BLACK (registered trademark)” (manufactured by Denki Kagaku Kogyo Co., Ltd.) was used. As the binder, modified polyacrylonitrile was used. Subsequently, the prepared positive electrode mixture was applied to a foil-like aluminum positive electrode current collector having a thickness of 15 μm, dried at 120 ° C., and then pressed three times at 40 MPa to form an electrode plate. Then, the electrode plate was punched into a disk shape having a diameter of 15 mm to obtain a positive electrode for a non-aqueous secondary battery. For this positive electrode, measure the thickness of the positive electrode at five locations and average the thickness of the positive electrode, subtract the thickness of the positive electrode current collector made of aluminum from the thickness of the positive electrode, and increase the thickness of the positive electrode mixture layer Asked. The volume of the positive electrode mixture layer was calculated by multiplying the thickness of the obtained positive electrode mixture layer by the area. Moreover, the mass of the positive electrode was measured, the mass of the positive electrode current collector made of aluminum was subtracted from the mass of the positive electrode, and the mass of the positive electrode mixture layer was determined. The density of the positive electrode mixture layer was obtained by dividing the mass of the obtained positive electrode mixture layer by the volume of the positive electrode mixture layer. The results are shown in Table 4.

The non-aqueous secondary battery was manufactured using the manufactured non-aqueous secondary battery positive electrode and the non-aqueous secondary battery negative electrode made of metallic lithium. As the non-aqueous electrolyte, a solution obtained by dissolving LiPF ₆ to a concentration of 1.0 mol / L in a solvent in which ethylene carbonate and dimethyl carbonate were mixed at a volume ratio of 1: 2 was used.

Next, a charge / discharge test was performed on each manufactured nonaqueous secondary battery, and a discharge capacity was measured. The charge / discharge test was conducted at an environmental temperature of 25 ° C.
For charging, constant current and constant voltage charging is performed at a current equivalent to 0.05 C up to an upper limit voltage of 4.6 V, and for discharging, after resting for 30 minutes, a constant current equivalent to 0.05 C is performed to a lower limit voltage of 2.5 V Then, the discharge capacity was measured after this charge / discharge.

  Next, a charge / discharge test was performed on each manufactured non-aqueous secondary battery, a direct current resistance in each charged state was measured, and a practical SOC range and an effective capacity were obtained. The layered solid solution compound tested has a characteristic that the difference in direct current resistance between charging and discharging is large compared to the layered oxide-based positive electrode active material, and the resistance becomes particularly high during discharging. . Therefore, the practical SOC range was determined based on the measurement of DC resistance during discharge.

  The DC resistance was measured at a state where the SOC was charged to 90%, and thereafter at each measurement point until the SOC equivalent to 10% was discharged sequentially to reach SOC 10%. At each measurement point, a 1.2 mA current was applied for 10 seconds, and the potential difference before and after the application was divided by a current value of 1.2 mA to calculate a direct current resistance value.

  The practical SOC range to be obtained was defined as a range in which the measured DC resistance value was not more than twice the minimum value of DC resistance. That is, in each of the nonaqueous secondary batteries using the positive electrode active materials according to Examples 1 to 7 and Comparative Examples 1 to 3, the DC resistance was 56Ω or less because the minimum value of DC resistance was 28Ω. The SOC range was determined as the practical SOC range, and the fraction of the practical SOC range relative to the SOC of 100% (practical SOC fraction) was calculated. The effective capacity was calculated by multiplying the measured discharge capacity by the practical SOC fraction. The results are shown in Table 4 below.

  As shown in Table 4, in the nonaqueous secondary batteries according to Examples 1 to 7, the positive electrode active material is the layered solid solution compound secondary particle 1 with respect to the effective capacity value indicating the capacity in the practically acceptable SOC range. And Comparative Examples 1 and 2 composed of only one of the layered solid solution compound secondary particles 2, and the layered solid solution in which the positive electrode active material is an intermediate composition of the layered solid solution compound primary particle A and the layered solid solution compound primary particle B Compared to the non-aqueous secondary battery according to Comparative Example 3 composed only of the compound primary particles C, the battery was improved. The reason why the effective capacity of Comparative Example 3 is lower than that of Comparative Example 1 is that the behavior of DC resistance (DCR) of Comparative Example 3 is similar to that of Comparative Example 2 on the low SOC side. It is considered that the high SOC side shows a high resistance behavior similar to that of Comparative Example 1. As a result, it is surmised that the practical SOC range is narrow and the effective capacity is low.

  Moreover, Examples 2-5 which contain the layered solid solution compound secondary particle 1 and the layered solid solution compound secondary particle 2 at 0.5: 0.5 to 0.2: 0.8 are the layered solid solution compound secondary particle 1 and The effective capacity per volume was higher than that of Example 1 containing layered solid solution compound secondary particles 2 at 0.8: 0.2 and Example 6 containing 0.1: 0.9. From this, when the layered solid solution compound secondary particles 1 and the layered solid solution compound secondary particles 2 are contained at a mass ratio of 0.5: 0.5 to 0.2: 0.8, the capacity may be further increased. It became clear. Further, the layered solid solution compound primary particles A and the layered solid solution compound primary particles B in a mass ratio of 0.2: 0.8 and a layered solid solution compound secondary particle 3 having an average particle size of 4 μm and a layered solid solution compound 2 having an average particle size of 30 μm are used. Example 7 containing the secondary particles 4 at a mass ratio of 0.2: 0.8 was found to have a higher capacity.

  Therefore, the layered solid solution compound 2 contains two or more kinds of layered solid solution compounds having different atomic concentration ratios of nickel and manganese, and has an average particle diameter twice or more that of other layered solid solution compound secondary particles. It was confirmed that when the content of the secondary particles is 20% by mass or more and 90% by mass or less, the SOC range in which high output can be obtained is expanded, the density is increased, and the effective capacity per volume can be increased.

  In addition, this invention is not limited to above-described embodiment, Various modifications are included. For example, with respect to a part of the configuration of the embodiment, it is possible to add, delete, or replace another configuration.

DESCRIPTION OF SYMBOLS 1 Nonaqueous secondary battery 2 Positive electrode 3 Negative electrode 4 Separator 5 Battery can 6 Positive electrode lead piece 7 Negative electrode lead piece 8 Sealing lid 9 Sealing material 10 Insulating plate 100A-100H Positive electrode active material 101A-101H for nonaqueous secondary batteries Layered solid solution compound Primary particles 102A-102H Layered solid solution compound primary particles 110A-110H Layered solid solution compound secondary particles 120A-120H Layered solid solution compound secondary particles D1-D4 Average particle size d1-d4 Average particle size

Claims (15)

A first layered solid solution compound containing nickel and manganese; a second layered solid solution compound containing nickel and manganese, wherein the first layered solid solution compound is different in the ratio of the atomic concentration of nickel to the atomic concentration of manganese; Including
And when it contains at least two kinds of layered solid solution compound secondary particles having different average particle diameters, the large particle diameter of the two kinds of layered solid solution compound secondary particles is D1 and the small particle diameter is D2. D1 / D2 ≧ 2, and the mass ratio of the layered solid solution compound secondary particles having an average particle diameter of D1 is W1, and the mass ratio of the layered solid solution compound secondary particles having an average particle diameter of D2 is W2. A positive electrode active material for a non-aqueous secondary battery in which 0.2 ≦ W1 / (W1 + W2) ≦ 0.9.   2. The positive electrode active material for a non-aqueous secondary battery according to claim 1, wherein the W1 and W2 are 0.5 ≦ W1 / (W1 + W2) ≦ 0.8. A first layered solid solution compound containing nickel and manganese; a second layered solid solution compound containing nickel and manganese, wherein the first layered solid solution compound is different in the ratio of the atomic concentration of nickel to the atomic concentration of manganese; Including
The average particle diameter D3 of the layered solid solution compound secondary particles composed of the first layered solid solution compound is larger than the average particle diameter D4 of the layered solid solution compound secondary particles composed of the second layered solid solution compound, D3 / D4 ≧ 2, the mass ratio of the layered solid solution compound secondary particles composed of the first layered solid solution compound is W3, and the mass of the layered solid solution compound secondary particles composed of the second layered solid solution compound A positive electrode active material for a non-aqueous secondary battery in which 0.2 ≦ W 3 / (W 3 + W 4) ≦ 0.9 when the ratio is W 4.   The positive electrode active material for a non-aqueous secondary battery according to claim 3, wherein the W3 and W4 are 0.5 ≦ W3 / (W3 + W4) ≦ 0.8.   The layered solid solution compound secondary particles include at least two types of layered solid solution compound primary particles having different average particle diameters, and the average particle diameter of the two types of layered solid solution compound primary particles is d1, a large particle size. Is d1 / d2 ≧ 2, and the mass ratio of the layered solid solution compound primary particles having an average particle diameter of d1 is w1, and the mass ratio of the layered solid solution compound primary particles having an average particle diameter of d2 is w2. The positive electrode active material for a non-aqueous secondary battery according to claim 1, wherein 0.2 ≦ w1 / (w1 + w2) ≦ 0.9.   The positive electrode active material for a non-aqueous secondary battery according to claim 5, wherein w1 and w2 are 0.5 ≦ w1 / (w1 + w2) ≦ 0.8. The layered solid solution compound secondary particles include a layered solid solution compound primary particle composed of a first layered solid solution compound and a layered solid solution compound primary particle composed of a second layered solid solution compound,
The average particle diameter d3 of the layered solid solution compound primary particles composed of the first layered solid solution compound is larger than the average particle diameter d4 of the layered solid solution compound primary particles composed of the second layered solid solution compound, and d3 / d4 ≧ 2, and the mass ratio of the layered solid solution compound primary particles composed of the first layered solid solution compound is w3, and the mass ratio of the layered solid solution compound primary particles composed of the second layered solid solution compound is w4. The positive electrode active material for a non-aqueous secondary battery according to claim 1, wherein 0.2 ≦ w 3 / (w 3 + w 4) ≦ 0.9.   The positive electrode active material for a non-aqueous secondary battery according to claim 7, wherein w3 and w4 are 0.5 ≦ w3 / (w3 + w4) ≦ 0.8. The first layered solid solution compound and the second layered solid solution compound are each represented by the following general formula (1):
_{xLi 2 MnO 3 - (1-} x) LiNi a Mn b Co c M d O 2 (1)
[Wherein, x, a, b, c and d have the following relationships: 0.2 ≦ x ≦ 0.8, 0.3 ≦ a <1.0, 0 ≦ b ≦ 0.6, 0 ≦ c <0.5, 0 ≦ d ≦ 0.05 is satisfied, and M is a group consisting of Fe, Ti, Zr, Al, Mg, Cr, V, Nb, Ta, W, Mo, Cu, Zn, Sn, and Ru. It is at least one element selected from more. ]
The positive electrode active material for non-aqueous secondary batteries in any one of Claims 1-8 which have a composition represented by these. Of the first and second layered solid solution compounds, the ratio of the atomic concentration of nickel and the atomic concentration of manganese of the layered solid solution compound having a high nickel atomic concentration is C ₁ , and the nickel atoms of the layered solid solution compound having a high atomic concentration of nickel when the ratio of the atomic concentration of concentration and manganese was _{C 2, C} 1> _{C 2 and,, 1.3 ≦ C 1 / C} 2 ≦ 7.0 non according to any one of claims 1 to 9 Cathode active material for aqueous secondary batteries.   The atomic concentration of nickel in the first layered solid solution compound and the atomic concentration of nickel in the second layered solid solution compound are 2.4 mol% or more and 9.5 mol% or less, respectively. The positive electrode active material for non-aqueous secondary batteries.   The positive electrode active material for a non-aqueous secondary battery according to any one of claims 1 to 11, wherein the first layered solid solution compound and the second layered solid solution compound each contain only nickel and manganese as transition metals.   The positive electrode for non-aqueous secondary batteries containing the positive electrode active material for non-aqueous secondary batteries in any one of Claims 1-12.   A non-aqueous secondary battery comprising the positive electrode for a non-aqueous secondary battery according to claim 13.   A vehicle-mounted non-aqueous secondary battery module comprising the non-aqueous secondary battery according to claim 14.

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