TWI775568B - High-capacity lithium titanate battery - Google Patents

Abstract

The present invention provides a high-capacity lithium titanate battery, which at least includes a metal shell with an accommodating space therein; a positive electrode plate is located in the accommodating space, and the positive electrode plate is composed of a first base material and at least one The positive electrode active material coating is composed; a negative electrode sheet is located in the accommodating space, and the negative electrode sheet is composed of a second base material and at least one negative electrode active material coating; at least one separator is located in the accommodating space, and is located between the positive electrode sheet and the negative electrode sheet, so that the two will not directly contact each other; and an electrolyte, which is a solution filled in the accommodation space; wherein, the thickness of the positive electrode active material coating is 37 mm ± 2 micrometers (μm), the thickness of the anode active material coating is 63 ± 2 μm, and the thickness of the separator is 9 ± 1 μm.

Description

High-capacity lithium titanate battery

The present invention relates to a secondary lithium-ion battery, especially a high-capacity lithium titanate rechargeable battery.

Lithium-titanate battery (Lithium-titanate battery) is a lithium-ion battery, and its positive electrode material usually uses lithium-ion-rich lithium cobalt oxide (LiCoO ₂ ), lithium manganate (LiMn ₂ O ₄ ), lithium nickelate (LiNiO _{2 )} ) or lithium ternary (NMC) mixed with the above three materials, and lithium ternary mixed with other materials (such as NCA, LiNi _0.8 Co _0.15 Al _0.05 O ₂ ), etc.; the negative electrode material is lithium titanate (Li ₄ Ti ₅ O ₁₂ ).

Please refer to FIG. 1, the conventional lithium titanate battery A is composed of a positive electrode sheet B, two separators C, E and a negative electrode sheet D, wherein the positive electrode sheet B is coated on both sides of the positive electrode sheet substrate B2 The positive electrode active material coating B1 (such as: lithium cobalt oxide material) is formed, the negative electrode sheet D is formed by coating the negative electrode active material coating D1 (such as: lithium titanate material) on both sides of the negative electrode sheet substrate D2, and the positive electrode sheet B and A separator C is provided in the middle of the negative electrode sheet D for insulation. In a cylindrical battery, the combined positive electrode sheet B and negative electrode sheet D are wound and placed in a circular container. Another layer of isolation film E needs to be added to the inner edge of D.

Continuing from the above, the existing lithium titanate battery generally adopts the composition structure, taking the cylindrical battery model 18650 (battery diameter 18.5 mm (mm), length 65 mm) as an example, and with the auxiliary description in Figure 1, the aluminum foil of the positive electrode B The thickness of the substrate (that is, the positive electrode sheet substrate B2) is 16 ± 1 μm (μm, that is, 10 ⁻⁶ m), the thickness of the positive electrode active material coating B1 is 39 ± 2 μm, and the aluminum foil substrate of the negative electrode sheet D ( That is, the thickness of the negative electrode sheet base material D2) is also 16 ± 1 μm, the thickness of the negative electrode active material coating D1 is 43 ± 2 μm, and the thicknesses of the separators C and E are 16 ± 1 μm. The assembly thickness of D and the two layers of separators C and E is 228 ± 12 μm, and is filled with electrolyte. The total capacity of a single battery is about 1300 milliamperes (mAh), and the volumetric energy density is 233 Wh/L (Wh/L).

Reducing the thickness of the aluminum foil substrate and separator can reduce the ineffective volume occupied by no active material; while increasing the thickness of the positive and negative material coatings can increase the effective volume ratio of active materials. Just like the semiconductor manufacturing process, only by breaking through the limitations of the manufacturing process and continuously improving the research and development of production control, can the capacity density of the battery be continuously improved.

In the process of coating and rolling the positive and negative electrode materials, in order to make the pole piece reach a certain flatness, the pole piece will be stretched from the feeding roller and the receiving roller. If the thickness of the aluminum foil is too thin, it is easy to be The lateral shear stress generated by the tension causes the aluminum foil to tear, which is the bottleneck of the current lithium titanate battery positive and negative electrodes that cannot use thinner aluminum foil substrates.

In addition, when the pole piece is cut, the cutter needs to cut the aluminum foil substrate and the double-sided active material coating on it. Due to the influence of the hardness of the coating, the shear stress of the upper and lower disc knives is greater than that of the coating particles. The bonding force between them will cause cracks in the coating material and the phenomenon of peeling off the powder. At the same time, the pole piece substrate will also be damaged by shearing force, resulting in sharp spurs on the cutting edge of the aluminum foil, especially the positive lithium cobalt oxide material. If the degree of brittleness and hardness is particularly high, a larger cutting force is required, and a larger cutting shear stress will cause a larger spur. It will pierce the separator and short-circuit with the adjacent negative pole piece, which is the main reason why the current lithium titanate battery cannot reduce the thickness of the separator.

To sum up, the thickness of the coating of the positive and negative materials is limited by the limits of the pole piece coating, rolling, cutting and other processes. Various means are often used to improve the existing techniques, including: adding an adhesive to increase the coating thickness , Add a conductive agent to maintain the conductivity of the thickened coating; in addition, adjust the formula of the pole piece to make the pole piece soft, keep the cutting edge sharp, use negative pressure vacuuming when winding, etc., can remove the burrs or suspended particles on the pole piece Substance removal, however, these well-known techniques have also been exhausted. How to find the best ratio of the thickness of the positive and negative coatings, so that the reaction between the positive and negative active materials can achieve the most sufficient reaction, has become the key to improving the battery capacity density. Lithium titanate battery manufacturers often use trial and error to adjust the relative thickness of the positive electrode coating and the negative electrode coating, which often wastes excess materials and fails to achieve the best overall capacity density.

Compared with lithium ion batteries such as lithium cobalt oxide, lithium ternary, and lithium iron phosphate, lithium titanate batteries have the advantages of high safety, fast charging, long service life, and suitable for use in low temperature environments. However, the nominal voltage of the battery It is 2.4 volts (V), which causes the disadvantage of low battery capacity density. Therefore, how to improve the capacity density of lithium titanate batteries has become the competition of lithium titanate battery technology.

The factors affecting the overall capacity density of a battery are mainly divided into two parts: material chemical properties and physical volume. In order to improve the capacity density of the battery, most of the early lithium titanate batteries started from improving the material itself and additives in the laboratory, and gradually increased the weight capacity density of the lithium titanate material to 160 milliampere hours/gram (mAh/g), which is very Close to the theoretical value of 175mAh/g, in terms of the chemical properties of lithium titanate materials, the room for further improvement is already very limited.

Compared with other lithium-ion battery manufacturers, there are very few manufacturers with lithium titanate battery manufacturing practice. Except for the theory of material characteristics, the various characteristic data and control parameters of production are limited. possible methods, lack of a complete systematic study. The battery cell is composed of a positive electrode, a negative electrode, a separator, an electrolyte, a container, etc. The main volume is: the aluminum foil substrate (collector) of the positive electrode sheet, the active material coating (active material) of the positive electrode, and the aluminum foil of the negative electrode sheet. Substrate and anode active material coating, as well as separator, so the capacity density of the battery is in addition to the capacity density corresponding to the chemical characteristics of the positive and negative electrode material itself, how to improve the coating, rolling, cutting, rolling of battery manufacturing The winding process and making good use of the limited physical volume space have become the key to determining the battery capacity density.

In view of the fact that lithium titanate battery has become a common type of battery for energy storage equipment and electric vehicle products, the inventor has finally designed a high The capacity lithium titanate battery is expected to effectively provide better products and give better use experience through the advent of the present invention.

One of the objectives of the present invention is to provide a high-capacity lithium titanate battery, which at least includes a metal shell with an accommodating space therein; material and at least one positive electrode active material coating; a negative electrode sheet, located in the accommodating space, the negative electrode sheet is composed of a second base material and at least one negative electrode active material coating; at least one separator is located in the in the accommodating space and between the positive electrode sheet and the negative electrode sheet, the separator can separate the positive electrode sheet and the negative electrode sheet so that the two will not directly contact each other; and an electrolyte is filled in the The solution in the accommodating space, this electrolyte can transfer metal ion substance in this accommodating space; Wherein, the thickness of this positive electrode active material coating is 37 ± 2 microns, the thickness of this negative electrode active material coating is 63 ± 2 microns, The thickness of the isolation film is 9±1 μm.

Optionally, the material of the first substrate and the second substrate is aluminum foil.

Optionally, the thicknesses of the first substrate and the second substrate are 10±1 μm.

Optionally, the composition thickness of the pole piece of the high-capacity lithium titanate battery is 238 ± 12 microns.

Optionally, the effective volume energy density of the positive electrode sheet and the negative electrode sheet is more than 310 Wh/L.

Optionally, the positive electrode sheet and the negative electrode sheet are respectively applied with a tensile force of 6.7 ± 0.3 megapascals through a rolling machine, and the inclination of the tensile horizontal angle is formed within ± 1.5 degrees.

Optionally, the material of the first substrate and the second substrate is copper foil.

Optionally, the thicknesses of the first substrate and the second substrate are 6±1 μm.

Optionally, the composition thickness of the pole piece of the high-capacity lithium titanate battery is 230 ± 12 microns.

Optionally, the effective volume energy density of the positive electrode sheet and the negative electrode sheet is more than 320 Wh/L.

Another object of the present invention is to provide a high-capacity lithium titanate battery, which at least includes a metal shell, which is provided with an accommodating space; material and at least one positive electrode active material coating; a negative electrode sheet, located in the accommodating space, the negative electrode sheet is composed of a second base material and at least one negative electrode active material coating; at least one separator is located in the in the accommodating space and between the positive electrode sheet and the negative electrode sheet, the separator can separate the positive electrode sheet and the negative electrode sheet so that the two will not directly contact each other; and an electrolyte is filled in the The solution in the accommodating space, the electrolyte can transfer metal ion substances in the accommodating space; wherein, the product of the compaction density, coating thickness, capacity density and active material ratio of the positive electrode active material coating is equivalent The product of compaction density, coating thickness, capacity density and active material ratio of the negative electrode active material coating.

Optionally, the ratio of the coating thickness of the positive electrode active material coating to the coating thickness of the negative electrode active material coating is 5.7:10 to 6.1:10.

Another object of the present invention is to provide a high-capacity lithium titanate battery, which at least includes a metal shell with an accommodating space therein; The base material is composed of at least one positive electrode active material coating; a negative electrode sheet is located in the accommodating space, and the negative electrode sheet is composed of a second base material and at least one negative electrode active material coating; at least one separator is located in the In the accommodating space and located between the positive electrode sheet and the negative electrode sheet, the separator can separate the positive electrode sheet and the negative electrode sheet so that the two do not directly contact each other; and an electrolyte is filled in the The solution in this accommodating space, this electrolyte can transfer metal ion substance in this accommodating space; Wherein, the thickness of this positive electrode active material coating is 37 ± 2 microns, the thickness of this negative electrode active material coating is 63 ± 2 microns , the thickness of this separator is 9 ± 1 microns, and the product of the compaction density, coating thickness, capacity density and active material ratio of the positive electrode active material coating is equivalent to the pressure of the negative electrode active material coating. The product of solid density, coating thickness, capacity density and active material ratio.

In order to facilitate your examination committee to be able to further understand and understand the purpose of the present invention, technical features and effects thereof, the following examples are given to coordinate the drawings, and the detailed description is as follows:

In order to make the purpose, technical content and advantages of the present invention clearer, the embodiments disclosed in the present invention will be described in further detail below in conjunction with the specific embodiments and with reference to the accompanying drawings. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification, and the present invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be based on different viewpoints and applications. , various modifications and changes can be made without departing from the concept of the present invention. In addition, it is stated in advance that the accompanying drawings of the present invention are merely schematic illustrations and are not drawn according to the actual size.

It should be understood that the examples used anywhere in the specification of the present invention, including the use of any terms, are illustrative only and in no way limit the scope and meaning of the present invention or any terms. Likewise, the present invention is not limited to the various embodiments disclosed in the specification. Although the terms first, second, or third, etc. may be used herein to describe various elements, each such element should not be limited by the foregoing terms, which are primarily used to distinguish one element from another and should not be used for any The elements impose any substantial limitations and should not limit the order in which the various elements may be assembled or arranged in practical application.

The present invention relates to a high-capacity lithium titanate battery. Please refer to FIGS. 2 to 6. In the first embodiment, the lithium titanate battery 1 at least includes a metal casing 2, and an accommodating space 20 is arranged therein. A positive electrode sheet 3 is located in the accommodating space 20, and the positive electrode sheet 3 is composed of a first substrate 32 and at least one positive electrode active material coating 31; a negative electrode sheet 4 is located in the accommodating space 20, and the negative electrode The sheet 4 is composed of a second substrate 42 and at least one negative electrode active material coating 41; at least one separator 5 is located in the accommodating space 20, and is located between the positive electrode sheet 3 and the negative electrode sheet 4, the isolation The membrane 5 can separate the positive electrode sheet 3 and the negative electrode sheet 4 so that the two do not directly contact each other; and an electrolyte 6 is a solution filled in the accommodating space 20, and the electrolyte 6 can be stored in the accommodating space 20. Transfer metal ion substance in space 20; Wherein, the thickness of this positive electrode active material coating 31 is 37 ± 2 μm, the thickness of this negative electrode active material coating 41 is 63 ± 2 μm, the thickness of this separator 5 is 9 ± 1 μm.

Continuing from the above, please refer to Figures 2 to 3. In the first embodiment, lithium cobalt oxide is used as a representative example of the positive electrode material of the present invention, and its chemical reaction formula is: Positive electrode: LiCoO ₂ ⇌ Li _1-x CoO ₂ + _x Li ⁺ + _x e ^- ; negative electrode: Li ₄ Ti ₅ O ₁₂ + _x Li ⁺ + _x e ^- ⇌ Li ₄ + _x Ti ₅ O ₁₂ .

On top of that, the material of the first base material 32 and the second base material 42 is aluminum foil, and the thickness of the first base material 32 and the second base material 42 is 10 ± 1 μm, so that the high-capacity lithium titanate battery The pole piece composition thickness of the pool is 238 ± 12 μm, and wherein, the pole piece composition thickness is composed of a first base material 32, two layers of positive active material coatings 31, one second base material 42, two layers of negative active material coatings. 41 and two separators 5 are added together, and the effective volume energy density of the positive electrode sheet 3 and the negative electrode sheet 4 is above 310 Wh/L.

Please refer to FIGS. 2 and 3 again. In the second embodiment, the first substrate 32 and the second substrate 42 are made of copper foil, and the first substrate 32 and the second substrate are made of copper foil. The thickness of 42 is 6 ± 1 μm, and the thickness of the pole piece composition of this high-capacity lithium titanate battery is 230 ± 12 μm, wherein, the thickness of this pole piece composition is composed of a first base material 32, two layers of positive electrode active material coatings. 31. A second base material 42, two negative electrode active material coatings 41 and two separators 5 are added together, and the effective volumetric energy density of the positive electrode sheet and the negative electrode sheet is 320 watt-hours/liter (WH/L). L) above.

Please refer to FIGS. 3 to 6. In this embodiment, the first substrate 32 and the second substrate 42 are in the process of coating and rolling the positive and negative materials. Research and analysis found that the machine applied The tensile force of the aluminum foil will extend the aluminum foil, but it is not the reason for the tearing of the aluminum foil, but when the surface of the aluminum foil is not parallel to the tensile force, the lateral shear stress generated by the tensile force exceeds the shear stress that the aluminum foil can withstand and tear. After mechanical calculation and material shear stress comparison, it is concluded that the angle between the aluminum foil plane and the machine's applied tensile force of 6.7 ± 0.3 million Pascals (MPa) needs to be controlled within ± 1.5 degrees, and the thinnest can be 10 ± 1 μm Aluminum foil, can still maintain the aluminum foil without breaking.

Please refer to Figures 4 to 6. The battery pole pieces coated with active material are fed into the roller press 8 from the end of the discharge shaft 7, and after being compacted by the rollers, they are recovered into rolls at the end of the take-up shaft 9. When the feeding shaft 7 before rolling or the receiving shaft 9 after rolling is inclined, the normal stress F _X of the tension will generate a lateral vertical component F _Y , when the shear stress S _S in the direction is too large. , which will cause tearing and damage of the pole piece substrate. In order to make the pole piece have a certain flatness during rolling, the inventor has learned that the calculation method is as follows after many practical researches and tests: vertical component force (F _Y ) = total tensile force (F) × sin a; shear stress (S _S ) = F _Y / (total width of pole piece (w) × assembly thickness (t)); Tensile tension (S _N ) = F / (w × t).

On the bearing, the feeding roller must have a tensile tension (S _N ) of at least 6 ± 0.3 MPa, and the shear stress (S _S ) strength of the aluminum foil is 0.18 ± 0.01 MPa, from which it is calculated that the horizontal inclination angle of the feeding roller should not exceed sin ^-1 (0.18/6) = 1.72 degrees. When applied to an aluminum foil substrate with a thickness of 10 μm and a total pole piece width (w) of 450 mm, the total tensile force (F) applied by the roller is calculated as follows: F= S _N × w × t = 6 MPa × 0.45 m × 10 μm = 27 ± 1.5 Newtons (N).

On top of that, in order to optimize the various qualities of the pole piece rolling and the level control of the rollers, the unwinding shaft 7 is increased to a tensile force of 30 ± 1.5 N, that is, the total tensile force (F) is increased to 6.7 ± 0.3 MPa, In order to ensure that the shear stress (S _S ) is less than 0.18 ± 0.01 MPa, that is, the horizontal inclination angle of the discharge shaft 7 must be controlled within ± 1.5 degrees (∘), the calculation method is as follows: S _N = F / (w × t) = 30 N / (0.45m × 10 μm) = 6.7 MPa; a = sin ^-1 (0.18 / 6.7) = 1.54∘.

In addition, replacing the aluminum foil with a copper foil with a higher shear stress (S _S ) can further reduce the thickness of the pole piece substrate. Similarly, a tensile force of 30 ± 1.5 N is applied to the discharge shaft 7, that is, the total width of the pole piece ( w) The 450 mm copper foil base material bears a total tensile force (F) of 6.7 ± 0.3 MPa, and controls the horizontal inclination angle of the feeding roller within ± 1.5 degrees to ensure that the shear stress is less than 0.18 ± 0.01 MPa, the thinnest can be used The copper foil of 6 ± 1 μm is used as the base material of the pole piece.

The positive electrode active material coating 31 and the negative electrode active material coating 41 are adjacent to each other with the separator 5 as the boundary. For each corresponding unit area, under the limit of the limit thickness of the coating, it is necessary to prepare two kinds of materials. content ratio, so that the positive and negative active materials can achieve the most sufficient chemical reaction, please refer to Figures 2 to 3. In the third embodiment, the inventors have studied the positive active material coating 31 and the negative active material. The optimal thickness ratio of the coating 41, and after careful analysis of various factors affecting the capacity through the experimental results, it is known: the compaction density _AP (gram/cubic centimeter (g/cm ³ )) of the positive active material coating 31 , the product of the positive electrode coating thickness d _P (centimeter (cm)), the capacity density EP (milliampere hour/gram (mAh/g)) and the active material ratio R _{P (} percentage (%)), which is equivalent to The compaction density _AN (gram/cubic centimeter (g/cm ³ )) of the negative electrode active material coating, the negative electrode coating thickness d _N (centimeter (cm)), the capacity density _EN (milliampere hour/gram (mAh) /g)) and the product of the active substance ratio R _N (percentage (%)), namely: A _P × d _P × E _P × R _P = A _N × d _N × E _N × R _N .

Continuing from the above, in this embodiment, the _AP value is 3.66 g/cm ³ , the _{EP value is 145mAh/g, the R P value} is 96%, the _AN value is 2.0 g/cm ³ , and the E _N value is 160mAh/g g. The value of R _N is 94%. Therefore, according to the above calculation, d _P / d _N = 300.8 / 509.5 = 59%, but not limited to this. In actual production, there may also be tolerance problems, making the positive electrode The ratio of coating thickness _dP to the anode coating thickness _dN can be 59±2% (ie, 5.7:10 to 6.1:10). Therefore, in the case where the positive and negative electrode capacitances are equivalent, the thickness of the negative electrode coating d _N will be greater than the thickness d _P of the positive electrode coating _. In terms of adhesion and cutting powder, it can be said that the capacity of the lithium titanate battery 1 is determined by the thickness d _N of the negative electrode coating. Limited by the negative electrode coating production process, the thickness d _N of the negative electrode coating with lithium titanate as the negative electrode active material coating 41 that can currently be stable in quality is 63 ± 2 μm, and then according to the above-mentioned thickness d _P of the positive electrode coating and The ratio of the negative electrode coating thickness d _N is calculated from 5.7:10 to 6.1:10, and the positive electrode coating thickness d _P is 37 ± 2 μm. The thickness d _P of the positive electrode coating and the thickness d _N of the negative electrode coating, with regard to the existing pole piece roll cutting process, the separator 5 with a thickness of 9±1 μm can be used, and the control burr will not pierce the separator 5 so as to cause the positive electrode piece 3 Short circuit with negative electrode 4.

Furthermore, the total capacity Q of the battery pole piece is obtained from the product of the capacitance per unit area and the total area of the pole piece, that is, the compaction density, coating thickness, capacity density, active material ratio, pole piece width H (such as As shown in Figure 2, that is, the product of the inner height of the casing 2) and the lateral length L of the pole piece, taking the conventional cylindrical battery 18650 as an example, the inner space of the metal can can accommodate the pole piece wound to a diameter of 17.6 mm and a height of 55mm (ie, 5.5 cm), the volume of the cylinder is 13380 mm ³ . However, when the pole piece is wound, it needs to deduct about 3% of the invalid accommodation space in the center (for example, the space occupied by the reel), Therefore, the effective accommodating space inside the metal can is 12979 mm ³ ; the stretched volume before the pole piece and the insulating sheet are wound is {(the thickness of the positive electrode coating × 2 + the thickness of the positive pole piece substrate) + (the thickness of the negative electrode coating × 2 + Negative pole piece base material thickness) + (separator film thickness × 2)} × H × L, and due to the material deformation in the thickness direction when the pole piece is wound, it cannot be completely tightly fitted, and there is still a gap between each layer of pole pieces. A 10% allowable deformation volume is required. Using the existing technology, the assembly thickness (t) of the positive and negative electrode sheets plus the two layers of separators is 228 μm. Considering the possible tolerance problems during production, it can be wound in the accommodating space 20 The transverse length L of the pole piece is obtained from the average value of each thickness by the following formula, {(39 × 2 + 16) + (43 × 2 + 16) + (16 × 2)} × 1.1 / 1000 × 55 × L =12979 mm ³ ; the lateral length L of the pole piece is 941 mm.

Continuing from the above, the capacity of the pole piece is calculated as the capacitance per unit area multiplied by the total area, that is, the total positive capacity Q _P = (A _P × d _P × E _P × R _P ) × H × L = (3.66 × 0.0039 × 2 × 145 × 0.96) × 5.5 × 94.1 = 2057 mAh; total negative electrode capacity Q _N = (A _N × d _N × E _N × R _N ) × H × L = (2.0 × 0.0043 × 2 × 160 × 0.94) × 5.5 × 94.1= 1339mAh.

As mentioned above, since the effective electric capacity of the battery is determined by the electric capacity of one of the positive electrode or the negative electrode with a smaller amount of material, the positive electrode material used in the prior art is 718mAh more than the negative electrode material, that is, 35% of the positive electrode material , which not only does not contribute to the capacity of the battery, but also occupies more ineffective space, so that the effective volumetric energy density of the battery pole piece is: 1339mAh × 2.4V / 13380 mm ³ = 240 ± 12 WH/L.

However, the present invention adopts an optimized design, wherein, when the first substrate 32 and the second substrate 42 are made of aluminum foil, substrates with a thickness of 10 ± 1 μm are used, and the thickness of the positive electrode active material coating 31 is 37 μm. ± 2 μm, the thickness of the negative electrode active material coating 41 is 63 ± 2 μm, the thickness of the separator 5 is 9 ± 1 μm, and the thickness of the pole piece composition is 238 ± 12 μm. When considering production, tolerance problems may be derived. The transverse length L of the aluminum foil pole piece that can be wound in the space of the can is obtained from the average value of each thickness by the following calculation formula: {(37 × 2 + 10) + (63 × 2 + 10) + (9 × 2)} × 1.1 / 1000 × 55 × Pole piece lateral length L = 12979 mm ³ ; pole piece lateral length L is 901 mm.

Continuing above, the total positive capacity Q _P = (A _P × d _P × E _P × R _P ) × H × L = (3.66 × 0.0037 × 2 × 145 × 0.96) × 5.5 × 90.1 = 1868mAh;

The total negative electrode capacity Q _N = (A _N × d _N × E _N × R _N ) × H × L = (2.0 × 0.0063 × 2 × 160 × 0.94) × 5.5 × 90.1 = 1878mAh;

The effective volumetric energy density of the battery pole piece is 1868mAh × 2.4V / 13380 mm ³ = 335 WH/L, but not limited to this. Considering the production tolerance and internal space availability issues, the effective volume of the battery pole piece The volumetric energy density can also be 335 ± 5% WH/L.

Continuing from the above, the capacity ratio of the present invention relative to the prior art is 1868/1339 = 1.395, and the electric capacity is increased by 39.5%. The experimental results confirm that the present invention is applied to the battery capacity of the 18650 model and can reach more than 1750mAh. Compared with the prior art capacity of 1300mAh, the electric capacity Capacity increased by 34.6%.

Furthermore, the present invention uses a thinner 6 ± 1 μm copper foil base material to replace the 10 ± 1 μm aluminum foil, and the total thickness (t) of the positive and negative electrode sheets plus the two layers of separators is 230 ± 12 μm, considering the possibility of production. Derived from the tolerance problem, the lateral length L of the copper foil pole piece that can be wound in the space of the container is derived from the average value of each thickness by the following calculation formula: {(37 × 2 + 6) + (63 × 2 + 6) + (9 × 2)} × 1.1 / 1000 × 55 × L = 12979 mm ³ ; the lateral length L of the copper foil pole piece is 933 mm.

Continuing above, the total positive capacity Q _P = (A _P × d _P × E _P × R _P ) × H × L = (3.66 × 0.0037 × 2 × 145 × 0.96) × 5.5 × 93.3 = 1935mAh;

The total negative electrode capacity Q _N = (A _N × d _N × E _N × R _N ) × H × L = (2.0 × 0.0063 × 2 × 160 × 0.94) × 5.5 × 93.3 = 1945mAh;

The effective volumetric energy density of the battery pole piece is 1935mAh × 2.4V / 13380 mm ³ = 347 WH/L, but not limited to this. Considering the production tolerance and internal space availability issues, the effective volume of the battery pole piece The volumetric energy density can also be 347 ± 5% WH/L.

On the basis of the above, the capacity ratio of the 6 μm copper foil substrate used in the present invention is 1935 / 1339 = 1.445 compared to the prior art, and the capacitance can be increased by 44.5%.

In addition to the cylindrical shape, the casing 2 of the present invention can also be rectangular. Please refer to Fig. 7. The positive electrode sheet 3 and the negative electrode sheet 4 after being rolled are rolled and separated by a separator 5. Flatten and put it into the casing 2 to form a prismatic battery; in addition, the material of the casing 2 can be aluminum foil, please refer to Figure 8, the positive electrode sheet 3 and the negative electrode sheet 4 after rolling, After being separated by the separator 5, it is cut and stacked into the casing 2, so that the positive electrode sheet 3, the negative electrode sheet 4 and the separator 5 are stacked in a sheet shape, and the top surface 21 of the casing 2 and the bottom surface of the casing 2 22 The positive electrode sheet 3, the negative electrode sheet 4 and the separator 5 will be wrapped inside to form a pouch battery, so that the space in the casing 2 can be fully utilized and the invalid space in the casing 2 can be reduced. . Furthermore, the number of the positive electrode sheet 3, the negative electrode sheet 4 and the separator 5 is not limited to the number drawn in Figure 8, and the manufacturer can match the corresponding number of positive electrode sheets 3, negative electrode sheets 4 and separators according to their product requirements. membrane 5.

According to the above, it is only a preferred embodiment of the present invention, but the scope of the rights claimed by the present invention is not limited to this. The equivalent changes that can be easily considered should all belong to the protection scope of the present invention.

[acquaintance]

A: Lithium titanate battery

B: positive electrode

B1: Cathode active material coating

B2: positive electrode substrate

C, E: isolation film

D: negative electrode

D1: Negative active material coating

D2: negative electrode substrate

[this invention]

1: Lithium titanate battery

2: Shell

20: accommodating space

21: Shell top surface

22: Bottom of the shell

3: positive electrode

31: Cathode active material coating

32: The first substrate

4: Negative sheet

41: Negative active material coating

42: Second substrate

5: Isolation film

6: Electrolyte

7: Unwinding shaft

8: Roller press

9: Receiving shaft

a: angle

d _N : thickness of anode coating

d _P : thickness of cathode coating

F: total tension

F _X : Normal stress

F _Y : Vertical component force

H: pole piece width

t: Assembly thickness

w: total width of pole piece

[Figure 1] is a cross-sectional view of the pole piece composition of a conventional lithium titanate battery; [Fig. 2] is a schematic diagram of the internal structure of the lithium titanate battery of the present invention; [Fig. 3] is a sectional view of the composition of the pole piece of the lithium titanate battery of the present invention; [Fig. 4] is a schematic diagram of the production of the pole piece roll pressing of the lithium titanate battery of the present invention; [Fig. 5] is a schematic diagram of the tension and shear stress analysis of the pole piece roll pressure of the lithium titanate battery of the present invention; [Fig. 6] is a schematic diagram of the pressure analysis of the pole piece roll of the lithium titanate battery of the present invention; [Fig. 7] is a schematic diagram of the internal structure of the rectangular battery of the lithium titanate battery of the present invention; and [Fig. 8] is a schematic diagram of the internal structure of the soft pack battery of the lithium titanate battery of the present invention.

1: Lithium titanate battery

3: positive electrode

31: Cathode active material coating

32: The first substrate

4: Negative sheet

41: Negative active material coating

42: Second substrate

5: Isolation film

d _N : thickness of anode coating

d _P : thickness of cathode coating

t: Assembly thickness

Claims (14)

A high-capacity lithium titanate battery at least comprises: a metal shell with an accommodating space therein; a positive electrode sheet located in the accommodating space, and the positive electrode sheet is composed of a first base material and at least one positive electrode active material coating composition; a negative electrode sheet is located in the accommodating space, the negative electrode sheet is composed of a second base material and at least one negative electrode active material coating; at least one separator is located in the accommodating space and located in the accommodating space. Between the positive electrode sheet and the negative electrode sheet, the separator can separate the positive electrode sheet and the negative electrode sheet so that the two will not be in direct contact with each other; and an electrolyte, which is a solution filled in the accommodating space, the The electrolyte can transfer metal ion substances in the accommodating space; wherein, the thickness of the positive electrode active material coating is 37±2 microns, the thickness of the negative electrode active material coating is 63±2 microns, and the thickness of the separator is 9 ±1 micron. The high-capacity lithium titanate battery according to claim 1, wherein the first substrate and the second substrate are made of aluminum foil. The high-capacity lithium titanate battery according to claim 2, wherein the thickness of the first substrate and the second substrate is 10±1 μm. The high-capacity lithium titanate battery according to claim 3, wherein the thickness of the pole piece of the high-capacity lithium titanate battery is 238±12 microns, and the aforementioned pole piece is composed of the first substrate, the second positive electrode active material The coating, the second substrate, the two negative electrode active material coatings and the two separators are formed. The high-capacity lithium titanate battery according to claim 4, wherein the effective volumetric energy density of the positive electrode sheet and the negative electrode sheet is more than 310 Wh/L. The high-capacity lithium titanate battery according to claim 5, wherein the tensile force applied to the positive electrode sheet and the negative electrode sheet respectively by a rolling machine is 6.7±0.3 megapascals, and the tension horizontal angle The slope of the system is formed within ±1.5 degrees. The high-capacity lithium titanate battery according to claim 1, wherein the first substrate and the second substrate are made of copper foil. The high-capacity lithium titanate battery according to claim 7, wherein the thickness of the first substrate and the second substrate is 6±1 μm. The high-capacity lithium titanate battery according to claim 8, wherein the thickness of the pole piece of the high-capacity lithium titanate battery is 230±12 μm, and the aforementioned pole piece is composed of the first substrate, the second positive electrode active material The coating, the second substrate, the two negative electrode active material coatings and the two separators are formed. The high-capacity lithium titanate battery according to claim 9, wherein the effective volumetric energy density of the positive electrode sheet and the negative electrode sheet is more than 320 Wh/L. The high-capacity lithium titanate battery as claimed in claim 10, wherein the tensile force applied to the positive electrode sheet and the negative electrode sheet respectively by a rolling machine is 6.7±0.3 megapascals, and the tension level is The inclination of the angle is formed within ±1.5 degrees. A high-capacity lithium titanate battery at least comprises: a metal shell, which is provided with an accommodating space; a positive electrode sheet, which is located in the accommodating space, and the positive electrode sheet is coated with a first base material and at least one positive electrode active material a negative electrode sheet, which is located in the accommodating space, and the negative electrode sheet is composed of a second substrate and at least one negative electrode active material coating; at least one separator is located in the accommodating space and is located in the positive electrode Between the tab and the negative tab, the separator can separate the positive tab and the negative tab so that the two are not in direct contact with each other; and An electrolyte, which is a solution filled in the accommodating space, and the electrolyte can transfer metal ion substances in the accommodating space; wherein, the compaction density, coating thickness, capacity density and activity of the positive electrode active material coating The product of the four ratios of the material is equivalent to the product of the compaction density, coating thickness, capacity density and active material ratio of the negative electrode active material coating, wherein the unit of the aforementioned compaction density is grams/cubic centimeter, The unit of the aforementioned coating thickness is centimeters, the aforementioned unit of the aforementioned capacity density is mAh/g, and the aforementioned unit of the aforementioned active material ratio is percentage. The high-capacity lithium titanate battery according to claim 12, wherein the ratio of the coating thickness of the positive electrode active material coating to the coating thickness of the negative electrode active material coating is 5.7:10 to 6.1:10. A high-capacity lithium titanate battery at least comprises: a metal shell with an accommodating space therein; a positive electrode sheet located in the accommodating space, and the positive electrode sheet is composed of a first base material and at least one positive electrode active material The coating is composed; a negative electrode sheet is located in the accommodating space, the negative electrode sheet is composed of a second base material and at least one negative electrode active material coating; at least one separator is located in the accommodating space and located in the accommodating space. Between the positive electrode sheet and the negative electrode sheet, the separator can separate the positive electrode sheet and the negative electrode sheet so that the two will not be in direct contact with each other; and an electrolyte, which is a solution filled in the accommodating space, the The electrolyte can transfer metal ion substances in the accommodating space; wherein, the thickness of the positive electrode active material coating is 37±2 microns, the thickness of the negative electrode active material coating is 63±2 microns, and the thickness of the separator is 9 ±1 micron, and the product of the compaction density, coating thickness, capacity density and active material ratio of the positive electrode active material coating is equivalent to the compaction density of the negative electrode active material coating The product of degree, coating thickness, capacity density and active material ratio, wherein, the unit of the aforementioned compaction density is g/cm3, the unit of the aforementioned coating thickness is cm, and the unit of the aforementioned capacity density is milliamp-hour/ Grams, the unit of the aforementioned active substance ratio is percentage.

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