CN115472814A - A new type of water-based secondary lithium battery and its negative electrode material, preparation method and application - Google Patents

Abstract

The invention relates to a novel water-based secondary lithium battery and its negative electrode material, preparation method and application. The novel water-based secondary lithium battery includes: a positive electrode, a negative electrode, a separator, and a mixed salt electrolyte; the negative electrode material of the negative electrode includes a binary niobium-based oxide compound material, the general formula is: xM _a O _b yNb ₂ O ₅ ; where, 1≤x≤9, 1≤y≤9, 1≤a≤3, 1≤b≤5; M is selected from Mg, Al , P, Ti, V, Zn, Ge, Zr, Hf one or more; among them, the bandgap width of Ma _{O b} > 3.0eV, used to improve the hydrogen evolution overpotential at the negative electrode interface; mixed salt electrolysis The liquid specifically includes a mixed salt electrolyte composed of at least one of an aqueous Li salt, an alkali metal ion salt, and a large cationic organic salt, wherein, in the mixed salt electrolyte, the aqueous Li salt and the alkali metal ion salt and large cationic organic salt The molar ratio of the total amount of cationic organic salts is not less than 1:10.

Description

A new type of water-based secondary lithium battery and its negative electrode material, preparation method and application

technical field

The invention relates to the field of material technology, in particular to a novel water-based secondary lithium battery and its negative electrode material, preparation method and application.

Background technique

With the development of secondary battery technology, aqueous batteries have the advantages of high safety, high safety, and environmental friendliness compared with organic ion batteries, and have received extensive attention in recent years. However, the shortcoming of aqueous batteries is that the energy density is still very low. Therefore, it is urgent to develop an aqueous battery system with higher energy density.

Water-in-salt (WIS) electrolyte has become a promising new electrolyte system in recent years due to its high electrochemical stability window (ESW) of 3V. In order to find a solution, it is an important research direction to develop electrode materials for aqueous batteries with higher specific capacity based on WIS electrolyte system.

However, we found in our research that although the WIS electrolyte can broaden the electrochemical stability window of the aqueous electrolyte to a certain extent, when a material with a lower redox potential is used for the negative electrode of the aqueous lithium-ion battery, the interface of the negative electrode is always Accompanied by severe hydrogen evolution side reactions, the aqueous electrolyte also has serious problems such as "Cathodic limit". This greatly limits the practical application of aqueous batteries.

Contents of the invention

The embodiment of the present invention provides a new type of water-based secondary lithium battery and its negative electrode material, preparation method and application. Anode materials for novel aqueous secondary lithium batteries include binary oxides composed of niobium oxide and wide-bandgap oxides, which can effectively suppress hydrogen evolution at the anode interface thanks to their wide bandgap width (>3.0eV) The side reaction occurs, and then realizes the stable operation of the binary niobium-based oxide material with a lower redox potential in the negative electrode of the aqueous battery.

In the first aspect, the embodiment of the present invention provides a novel water-based secondary lithium battery, including: a positive electrode, a negative electrode, a separator, and a mixed salt electrolyte;

The negative electrode material of the negative electrode includes a binary niobium-based oxide composite material; the general formula of the binary niobium-based oxide composite material is: xM _a O _b ·yNb ₂ O ₅ ; wherein, 1≤x≤9, 1 ≤y≤9, 1≤a≤3, 1≤b≤5; M is selected from one or more of Mg, Al, P, Ti, V, Zn, Ge, Zr, Hf; among them, M _a O The bandgap width of _b is >3.0eV, which is used to increase the hydrogen evolution overpotential at the negative electrode interface;

The mixed salt electrolyte specifically includes a mixed salt electrolyte composed of at least one of an aqueous Li salt, an alkali metal ion salt, and a large cationic organic salt, wherein, in the mixed salt electrolyte, the aqueous Li salt and the alkali The molar ratio of metal ion salts to the total amount of large cationic organic salts is not less than 1:10.

Preferably, the positive electrode material of the positive electrode includes: LiFePO ₄ , LiCoO ₂ , LiMn ₂ O ₄ , LiNi _0.5 Mn _1.5 O ₄ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _1/3 Co _1/3 Mn _1/3 A mixture of one or more of O ₂ , LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ , Li ₂ CoMnO ₄ , Li ₂ MnO ₃ ;

The diaphragm is any one of glass fiber, polypropylene diaphragm, non-woven cloth diaphragm, polyethylene diaphragm or polytetrafluoroethylene diaphragm.

Preferably, the aqueous Li salt includes: a mixture of one or more of LiPF ₆ , LiBF ₄ , LiNO ₃ , LiCl, LiClO ₄ , Li ₂ SO ₄ , LiAc, LiTFSI, LiOTF, LiFSI, LiBETI;

The alkali metal ion salt includes Na salt and/or K salt;

The Na salt includes: one or more mixtures of NaPF ₆ , NaBF ₄ , NaNO ₃ , NaCl, NaClO ₄ , Na ₂ SO ₄ , sodium acetate NaAc, NaTFSI, NaOTF, NaFSI, and NaBETI;

The K salt includes one or more mixtures of KPF ₆ , KBF ₄ , KNO ₃ , KCl, KClO ₄ , K ₂ SO ₄ , KAc, KTFSI, KOTF, KFSI, KBETI;

The cation in the large cationic organic salt comprises one of imidazolium ion, pyridinium ion, pyrrolium ion, piperidinium ion, morpholinium ion, quaternary ammonium salt ion, quaternary phosphonium salt ion or tertiary perjulium ion or multiple mixtures, anions include: Cl ^- , Br ^- , I ^- , PF ₆ ^- , BF ₄ ^- , CN ^- , SCN ^- , [N(CF ₃ SO ₂ ) ₂ ] ^- , [N(CN) ₂ ] ^- one or more of the mixture;

In the mixed salt electrolyte, the molar ratio of the aqueous Li salt to the total amount of the alkali metal ion salt and the large cationic organic salt is between 1:10 and 10:1.

Preferably, the positive electrode and/or negative electrode further includes a current collector; the current collector specifically includes any one of titanium, copper, platinum, nickel, gold, tungsten, molybdenum, tantalum and carbon, and is in the form of foam, mesh Shape, flake, carbon fiber cloth or pyrolytic graphite flake.

Preferably, the positive and/or negative electrodes also include binders and conductive additives;

The binder includes: one or more mixtures of polyvinylidene fluoride PVDF, polytetrafluoroethylene PTFE, acrylamide-acrylate copolymer, sodium alginate, and β-cyclodextrin;

The conductive additive includes: one or more mixtures of graphene, acetylene black, Ketjen black, Super P, carbon nanotubes, carbon fibers, BP2000, Vulcan XC or Denka.

In the second aspect, the embodiment of the present invention provides a negative electrode material for the new aqueous secondary lithium battery described in the first aspect above, the negative electrode material includes a binary niobium-based oxide composite material;

The general formula of the binary niobium-based oxide composite material is: xM _a O _b ·yNb ₂ O ₅ ; wherein, 1≤x≤9, 1≤y≤9, 1≤a≤3, 1≤b≤5 ; M is selected from one or more of Mg, Al, P, Ti, V, Zn, Ge, Zr, Hf; wherein, the bandgap width of M _a O _b > 3.0eV, in order to improve the negative electrode interface Hydrogen evolution overpotential.

Preferably, the binary niobium-based oxide composite material has an m×n×∞ shear-ReO ₃ structure, where m and n are both positive integers.

In a third aspect, an embodiment of the present invention provides a method for preparing the negative electrode material described in the second aspect above, including:

Mix the M source and Nb source in the required stoichiometric ratio by solid-phase ball milling or sol-gel method, and then sinter in air or inert gas atmosphere to obtain binary niobium-based oxide composite xM _a O _b ·yNb ₂ O is the negative electrode material _;

Wherein, the sintering temperature is 500°C-1400°C, and the sintering time is 1-72 hours.

Preferably, the M source is an oxide of any one or more of Mg, Al, P, Ti, V, Zn, Ge, Zr, Hf, or contains Mg, Al, P, Ti, Oxides of any one or more of V, Zn, Ge, Zr, and Hf.

In the fourth aspect, the embodiment of the present invention provides a use of the new water-based secondary lithium battery described in the first aspect above, and the new water-based secondary lithium battery is used for power batteries of electric vehicles, energy storage power stations, and power grids Energy storage, portable electronics, aviation reserve power, submarine reserve power or space reserve power.

The novel water-based secondary lithium battery provided by the embodiments of the present invention has a high hydrogen evolution overpotential, which can essentially suppress the hydrogen evolution side reaction of the water-based battery from the negative electrode material, thereby broadening its application range in the water-based electrolyte. In addition, the novel water-based secondary lithium battery of the present invention uses a binary oxide composite material for the negative electrode, and has the characteristics of high capacity, stable structure, and good cycle stability. The novel aqueous secondary battery of the present invention can be applied in a variety of scenarios, such as power battery scenarios applied to electric vehicles, energy storage scenario packages used in energy storage power stations and grid energy storage applications, portable electronic devices, Safety scenarios for the application of aviation reserve power, submarine reserve power, and aerospace reserve power.

Description of drawings

The technical solutions of the embodiments of the present invention will be further described in detail below with reference to the drawings and embodiments.

Fig. 1 is a schematic structural view of a novel aqueous secondary lithium battery provided by an embodiment of the present invention;

2 is a schematic diagram of the crystal structure of a binary niobium-based oxide composite material provided by an embodiment of the present invention;

3 is a schematic diagram of the crystal structure of the 2ZnO·17Nb ₂ O ₅ material provided in Example 1 of the present invention;

Fig. 4 is the X-ray diffraction (XRD) diagram of the 2ZnO·17Nb ₂ O ₅ material provided by Example 1 of the present invention;

Figure 5 is a scanning electron microscope (SEM) image of the 2ZnO·17Nb ₂ O ₅ material provided in Example 1 of the present invention;

Figure 6 is a transmission electron microscope (TEM) image of the 2ZnO·17Nb ₂ O ₅ material provided by Example 1 of the present invention;

Fig. 7 is the 0.2C constant current charge and discharge curve of the aqueous secondary lithium battery provided by Example 1 of the present invention with 2ZnO·17Nb ₂ O ₅ as the negative electrode material and LiMn ₂ O ₄ as the positive electrode material in the voltage range of 1.0-2.8V ;

8 is a schematic diagram of the 0.2C current density cycle performance of the aqueous secondary lithium battery provided in Example 1 of the present invention with 2ZnO·17Nb ₂ O ₅ as the negative electrode material and LiMn ₂ O ₄ as the positive electrode material in the voltage range of 1.0-2.8V;

9 is a schematic diagram of the 1C current density cycle performance of the aqueous secondary lithium battery provided in Example 1 of the present invention with 2ZnO·17Nb ₂ O ₅ as the negative electrode material and LiMn ₂ O ₄ as the positive electrode material in the voltage range of 1.0-2.8V;

Figure 10 shows the 0.1C current density constant current charge and discharge of the aqueous secondary lithium battery provided by Example 1 of the present invention with 2ZnO·17Nb ₂ O ₅ as the negative electrode material and LiMn ₂ O ₄ as the positive electrode material in the voltage range of 1.0-3.2V Graph;

Fig. 11 is a schematic diagram of the 1C cycle performance of the aqueous secondary lithium battery with 2ZnO·17Nb ₂ O ₅ as the negative electrode material and LiMn ₂ O ₄ as the positive electrode material provided in Example 1 of the present invention in the voltage range of 1.0-3.2V;

Fig. 12 is an in-situ XRD pattern of an aqueous secondary lithium battery with 2ZnO·17Nb ₂ O ₅ as the negative electrode material and LiMn ₂ O ₄ as the positive electrode material provided in Example 1 of the present invention within the voltage range of 1.0-2.8V;

Figure 13 is a schematic diagram of the crystal structure of the 2MgO·17Nb ₂ O ₅ material provided by Example 2 of the present invention;

Figure 14 is the XRD pattern of the 2MgO·17Nb ₂ O ₅ material provided by Example 2 of the present invention;

Figure 15 is an SEM image of the 2MgO·17Nb ₂ O ₅ material provided in Example 2 of the present invention;

Fig. 16 is a charge-discharge curve diagram of a water-based secondary full battery composed of 2MgO·17Nb ₂ O ₅ powder material and LiMn ₂ O ₄ provided in Example 2 of the present invention at a current density of 0.1C in the voltage range of 1.0-2.8V;

Figure 17 is a schematic diagram of the cycle performance of the aqueous secondary full battery composed of 2MgO·17Nb ₂ O ₅ powder material and LiMn ₂ O ₄ provided in Example 2 of the present invention at a current density of 1C in the voltage range of 1.0-2.8V;

Figure 18 is a schematic diagram of the crystal structure of the P ₂ O ₅ ·9Nb ₂ O ₅ material provided in Example 3 of the present invention;

Fig. 19 is a charge-discharge curve diagram of a water-based secondary full battery composed of P ₂ O ₅ 9Nb ₂ O ₅ powder material and LiCoO ₂ provided in Example 3 of the present invention at a current density of 0.1C in the voltage range of 1.0-2.8V ;

Fig. 20 is a schematic diagram of cycle performance at 1C current density in the voltage range of 2.8V provided by 1.0 for P ₂ O ₅ ·9Nb ₂ O ₅ powder material and LiCoO ₂ provided in Example 3 of the present invention to form an aqueous secondary full battery;

Figure 21 is a schematic diagram of the crystal structure of the ZrO ₂ ·7Nb ₂ O ₅ material provided in Example 4 of the present invention;

Fig. 22 is an XRD pattern of the ZrO ₂ ·7Nb ₂ O ₅ material provided in Example 4 of the present invention.

detailed description

The present invention will be further described below through the accompanying drawings and specific embodiments, but it should be understood that these embodiments are only used for more detailed description, and should not be construed as limiting the present invention in any form, that is, not intended To limit the protection scope of the present invention.

The present invention proposes a novel water-based secondary lithium battery, the structure of which is shown in Figure 1, including a positive electrode, a negative electrode, a diaphragm and a mixed salt electrolyte;

Positive electrode materials include: LiFePO ₄ , LiCoO ₂ , LiMn ₂ O ₄ , LiNi _0.5 Mn _1.5 O ₄ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNi _0.8 One or more of Co _0.1 Mn _0.1 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ , Li ₂ CoMnO ₄ , and Li ₂ MnO ₃ are mixed.

The negative electrode material of the negative electrode includes binary niobium-based oxide composite materials, the general formula is: xM _a O _b yNb ₂ O ₅ ; where, 1≤x≤9, 1≤y≤9, 1≤a≤3, 1≤ b≤5; M is selected from one or more of Mg, Al, P, Ti, V, Zn, Ge, Zr, and Hf; among them, the bandgap width of M _a O _b is >3.0eV, which is used to improve the negative electrode Hydrogen evolution overpotential at the interface; the binary niobium-based oxide composite has an m×n×∞ type shear _- ReO structure, where m, n are both positive integers. Fig. 2 is a schematic diagram of the crystal structure of a binary niobium-based oxide composite material provided by an embodiment of the present invention.

The positive and/or negative electrodes also include a current collector; the current collector specifically includes any one of titanium, copper, platinum, nickel, gold, tungsten, molybdenum, tantalum, and carbon, in the form of foam, mesh, sheet, One of carbon fiber cloth or pyrolytic graphite flake.

The positive and/or negative electrodes also include a binder and a conductive additive; wherein the binder includes: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), acrylamide-acrylate copolymer, sodium alginate, β - A mixture of one or more of cyclodextrins (β-CD); conductive additives include: one of graphene, acetylene black, Ketjen black, Super P, carbon nanotubes, carbon fibers, BP2000, Vulcan XC or Denka one or more mixtures.

The mixed salt electrolyte specifically includes a mixed salt electrolyte composed of at least one of an aqueous Li salt and an alkali metal ion salt, a large cationic organic salt, etc., wherein, in the mixed salt electrolyte, the aqueous Li salt and an alkali metal ion salt and a large The molar ratio of the total amount of cationic organic salts is not less than 1:10, more preferably the molar ratio of the aqueous Li salt to the total amount of alkali metal ion salts and large cationic organic salts is between 1:10 and 10:1.

Among them, the aqueous Li salt includes: LiPF ₆ , LiBF ₄ , LiNO ₃ , LiCl, LiClO ₄ , Li ₂ SO ₄ , LiAc, LiTFSI, LiOTF, LiFSI, and LiBETI; the alkali metal ion salt includes Na Salt and/or K salt; Na salt includes: one or more of NaPF ₆ , NaBF ₄ , NaNO ₃ , NaCl, NaClO ₄ , Na ₂ SO ₄ , sodium acetate (NaAc), NaTFSI, NaOTF, NaFSI, NaBETI Mixed; K salts include one or more of KPF ₆ , KBF ₄ , KNO ₃ , KCl, KClO ₄ , K ₂ SO ₄ , KAc, KTFSI, KOTF, KFSI, KBETI mixed; cations in large cationic organic salts include A mixture of one or more of imidazolium ions, pyridinium ions, pyrrolium ions, piperidinium ions, morpholinium ions, quaternary ammonium salt ions, quaternary phosphonium salt ions or tertiary percited ions, the anions include: Cl ^- , Br ^- , I ^- , PF ₆ ^- , BF ₄ ^- , CN ^- , SCN ^- , [N(CF ₃ SO ₂ ) ₂ ] ^- , [N(CN) ₂ ] ^- or a mixture of one or more.

The negative electrode material in the above-mentioned new type of water-based secondary lithium battery - the binary niobium-based oxide composite material can be mixed in the air by mixing the M source and the Nb source of the required stoichiometric ratio by the solid phase ball milling method or the sol-gel method. Or prepared by sintering in an inert gas atmosphere. In a specific implementation, the sintering temperature is 500°C-1400°C, and the sintering time is 1-72 hours. The M source can be any one or several oxides of Mg, Al, P, Ti, V, Zn, Ge, Zr, Hf, or it can also be an oxide containing Mg, Al, P, Ti, V, Oxides of any one or more of Zn, Ge, Zr, and Hf.

The novel water-based secondary lithium battery of the present invention uses _a binary oxide composite material composed of niobium oxide and wide bandgap oxide _MaOb as the negative electrode material, benefiting from its wide bandgap width (>3.0eV), The side reaction of hydrogen evolution can be effectively suppressed at the negative electrode interface, and a higher hydrogen evolution overpotential at the negative electrode interface can be achieved, thereby realizing the stable operation of the binary niobium-based oxide material with a lower redox potential in the negative electrode of the aqueous battery . In addition, due to the stable sheared _ReO3 crystal structure and abundant redox couples, the binary Nb-based oxide exhibits extremely high lithium intercalation cycle stability and high reversible specific capacity. Therefore, it is a very feasible solution to apply this kind of binary niobium-based oxide materials to the negative electrode of aqueous batteries to increase the energy density of aqueous batteries.

The novel aqueous secondary lithium battery proposed by the invention can be used for power batteries of electric vehicles, energy storage power stations, power grid energy storage, portable electronic equipment, aviation reserve power, submarine reserve power or aerospace reserve power, etc.

In order to better understand the technical solutions provided by the present invention, the following specific examples are used to illustrate the specific process of preparing binary niobium-based oxide composite materials by applying the methods provided in the above-mentioned embodiments of the present invention, and applying them to water-based binary Methods and properties of secondary lithium batteries.

Example 1

This example provides a preparation method of 2ZnO·17Nb ₂ O ₅ material and its application in water-based secondary lithium batteries.

Zinc oxide and niobium pentoxide were ball-milled and mixed for 3 hours at a speed of 600 rpm in a high-energy ball mill with absolute ethanol as a dispersant at a molar ratio of 2:17. After the ball-milled mixture was dried, it was placed in an air atmosphere sintering at 1200°C for 6 hours and cooling to room temperature to obtain 2ZnO·17Nb ₂ O ₅ powder.

Material performance characterization:

The crystal structure of the obtained product was analyzed by X-ray diffraction analyzer (XRD) and transmission electron microscope, and the morphology characteristics of the material were observed by scanning electron microscope. The crystal structure of the prepared 2ZnO·17Nb ₂ O ₅ powder material is shown in Fig. 3; the XRD diffraction pattern is shown in Fig. 4, the SEM pattern is shown in Fig. 5, and the SAED pattern is shown in Fig. 6. It can be seen that the synthesized samples have The diffraction peaks can point to the standard diffraction peaks of 2ZnO·17Nb ₂ O ₅ , which indicates that the pure phase 2ZnO·17Nb ₂ O ₅ material with sheared ReO ₃ structure was synthesized by this method. The 2ZnO·17Nb ₂ O ₅ material is in the form of random particles with a particle size between 1.0-10 microns.

Figure 7 shows the 2ZnO·17Nb ₂ O ₅ material obtained in Example 1 and LiMn ₂ O ₄ to form a water-based secondary full battery. The mass ratio of active materials is negative electrode: positive electrode = 1:2.5. It is the LiTFSI and bistrifluoromethanesulfonimide quaternary ammonium salt aqueous solution with a molar ratio of 5:3, and the charge and discharge curves at a current density of 0.2C in the voltage range of 1.0-2.8V. The reversible specific capacity of 2ZnO·17Nb ₂ O ₅ material can reach 179mAh/g in the first week, which is better than Li ₄ Ti ₅ O ₁₂ , which is currently the best anode material for aqueous secondary batteries with a similar electrochemical window. 155mAh/g.

Figure 8 and Figure 9 respectively show the above-mentioned 2ZnO·17Nb ₂ O ₅ material and LiMn ₂ O ₄ obtained in Example 1 to form an aqueous secondary full battery, under the current density of 0.2C and 1C in the voltage range of 1.0-2.8V Schematic diagram of the cycle performance. It has a capacity retention rate of 88% after 100 cycles at a low current density of 0.2C, and still has a capacity retention rate of 81% after 1000 cycles at a current density of 1C. The high reversible specific capacity and long cycle life of the aqueous secondary full battery with an excess of positive electrode above illustrate the characteristics of high capacity and structural stability of the 2ZnO·17Nb ₂ O ₅ material.

Figure 10 shows the 2ZnO·17Nb ₂ O ₅ material obtained in Example 1 and LiMn ₂ O ₄ to form an aqueous secondary full battery. The mass ratio of active materials is negative electrode: positive electrode = 1:1.6, which is equivalent to a capacity ratio of negative electrode: positive electrode =1:1.05, the rest of the composition is the same as above, and the charge and discharge curve is under the current density of 0.2C in the voltage range of 1.0-3.2V. The full battery shows a reversible specific capacity of 66mAh/g, a working voltage of about 2.43V, and an energy density of 161Wh/kg. Under the same positive electrode material, it is superior to other water-based battery negative electrode materials in the prior art.

Figure 11 shows the 2ZnO·17Nb ₂ O ₅ material obtained in Example 1 and LiMn ₂ O ₄ to form an aqueous secondary full battery. The mass ratio of active materials is negative electrode: positive electrode = 1:1.6, which is equivalent to a capacity ratio of negative electrode: positive electrode =1:1.05, schematic diagram of cycle performance at 1C current density in the voltage range of 1.0-3.2V. After 70 cycles, it still has high energy density and reversible specific capacity.

Figure 12 shows the 2ZnO·17Nb ₂ O ₅ material obtained in Example 1 and LiMn ₂ O ₄ to form an aqueous secondary full battery. The mass ratio of active materials is negative electrode: positive electrode = 1:2.5, within the voltage range of 1.0-2.8V In situ XRD test results. As shown in Figure 12, in the process of lithium intercalation and desorption of 2ZnO·17Nb ₂ O ₅ material, only the diffraction peak shifts and recovers, and no new diffraction peak is generated. It shows that the 2ZnO·17Nb ₂ O ₅ material can also maintain a stable and reversible structure in aqueous batteries.

Example 2

This example provides a preparation method of 2MgO·17Nb ₂ O ₅ material and its application in water-based secondary lithium batteries.

Magnesium oxide and niobium pentoxide were ball-milled and mixed for 3 hours at a speed of 600 rpm in a high-energy ball mill with absolute ethanol as a dispersant at a molar ratio of 2:17. After the ball-milled mixture was dried, it was placed in an air atmosphere sintering at 900°C for 12 hours and cooling to room temperature to obtain 2MgO·17Nb ₂ O ₅ material powder.

Material performance characterization:

The crystal structure of the obtained product was analyzed by X-ray diffraction analyzer (XRD) and transmission electron microscope, and the morphology characteristics of the material were observed by scanning electron microscope.

The 2MgO·17Nb ₂ O ₅ powder material prepared in this example has a monoclinic shear ReO ₃ crystal structure, as shown in FIG. 13 . Its XRD diffraction pattern is shown in Figure 14, and the SEM image is shown in Figure 15. It can be seen that the synthesized 2MgO·17Nb ₂ O ₅ material is in the form of random particles with a particle size between 1.0-10 microns.

Figure 16 shows the 2MgO·17Nb ₂ O ₅ powder material obtained in Example 2 and LiMn ₂ O ₄ to form a water-based secondary full battery. The mass ratio of active materials is negative electrode: positive electrode = 1:2.5, and the rest are the same as in Example 1. Charge and discharge curves at 0.1C current density within the voltage range of 1.0-2.8V. The reversible specific capacity of 2MgO·17Nb ₂ O ₅ powder material can reach 184mAh/g in the first week, which is better than Li ₄ Ti ₅ O ₁₂ , the current best anode material for aqueous secondary batteries with a similar electrochemical window, in aqueous batteries. 155mAh/g.

Figure 17 shows the 2MgO·17Nb ₂ O ₅ powder material obtained in Example 2 and LiMn ₂ O ₄ to form a water-based secondary full battery. The mass ratio of active materials is negative electrode: positive electrode = 1:2.5, in the voltage range of 1.0-2.8V Schematic diagram of the cycling performance at an internal 1C current density. It still has a capacity retention of 91% after 900 cycles at a current density of 1C. The above-mentioned high reversible specific capacity and long cycle life of the aqueous secondary full battery with an excess of positive electrode illustrate the characteristics of high capacity and structural stability of the 2MgO·17Nb ₂ O ₅ material.

Example 3

This example provides the electrochemical performance of an aqueous full battery assembled from P ₂ O ₅ ·9Nb ₂ O ₅ material and LiCoO ₂ .

Phosphorus pentoxide and niobium pentoxide were mixed for 3 hours in a high-energy ball mill with absolute ethanol as a dispersant at a mol ratio of 1:9 at a speed of 600 rpm, and after the ball-milled mixture was dried, the Sintering at 900° C. for 12 hours in an air atmosphere, and cooling to room temperature to obtain P ₂ O ₅ ·9Nb ₂ O ₅ material powder.

The P ₂ O ₅ ·9Nb ₂ O ₅ powder material prepared in this example has an orthogonally sheared ReO ₃ crystal structure, as shown in FIG. 18 .

Figure 19 shows the P ₂ O ₅ ·9Nb ₂ O ₅ powder material obtained in Example 3 and LiCoO ₂ to form a water-based secondary full battery. The mass ratio of active materials is negative electrode: positive electrode = 1:2.5, and other conditions are the same as in Example 1. , Charge and discharge curves at 0.1C current density in the voltage range of 1.0-2.8V.

Figure 20 shows the P ₂ O ₅ ·9Nb ₂ O ₅ powder material obtained in Example 3 and LiCoO ₂ to form a water-based secondary full battery. The mass ratio of active materials is negative electrode: positive electrode = 1:2.5, at a voltage of 1.0-2.8V Schematic diagram of cycle performance at 1C current density in the interval.

Example 4

This embodiment provides the preparation method of ZrO ₂ ·7Nb ₂ O ₅ material and its application in water-based secondary lithium battery.

Zirconium dioxide and niobium pentoxide were mixed in a high-energy ball mill with absolute ethanol as a dispersant at a speed of 600 rpm for 3 hours at a molar ratio of 1:7, and the ball-milled mixture was dried and placed in air In atmosphere, sinter at 1300°C for 12 hours, and cool to room temperature to obtain ZrO ₂ ·7Nb ₂ O ₅ material powder.

The ZrO ₂ ·7Nb ₂ O ₅ powder material prepared in this example has a sheared ReO3 crystal structure as shown in FIG. 21 , and its XRD diffraction pattern is shown in FIG. 22 .

The ZrO ₂ .7Nb ₂ O ₅ material obtained in Example 4 and the LiNi _0.8 Co _0.1 Mn _0.1 O ₂ positive electrode constitute an aqueous secondary full battery. The mass ratio of active materials is negative electrode: positive electrode = 1:2.0, and the rest of the conditions are the same as in the embodiment 1. In the voltage range of 1.0-2.8V, the reversible specific capacity can reach 165mAh/g in the first cycle at 0.1C current density, and it still has a capacity retention rate of 85% after 1000 cycles at 1C current density.

Example 5

This embodiment provides a preparation method of 4GeO ₂ ·Nb ₂ O ₅ material and its application in water-based secondary lithium batteries.

Germanium dioxide and niobium pentoxide were ball-milled and mixed for 3 hours at a speed of 600 rpm in a high-energy ball mill with absolute ethanol as a dispersant at a molar ratio of 4:1, and the ball-milled mixture was dried and placed in air In atmosphere, sinter at 1100°C for 12 hours, and cool to room temperature to obtain 4GeO ₂ ·Nb ₂ O ₅ material powder.

The 4GeO ₂ ·Nb ₂ O ₅ material obtained in Example 5 and the positive electrode of LiNi _0.6 Co _0.2 Mn _0.2 O ₂ constitute an aqueous secondary full battery. The mass ratio of active materials is negative electrode: positive electrode = 1:2.0, and the rest of the conditions are the same as in the embodiment 1. In the voltage range of 1.0-2.8V, the reversible specific capacity can reach 170mAh/g in the first cycle at 0.1C current density, and the capacity retention rate is still 81% after 1000 cycles at 1C current density.

Example 6

This embodiment provides the preparation method of HfO ₂ ·12Nb ₂ O ₅ material and its application in water-based secondary lithium battery.

Hafnium dioxide and niobium pentoxide were mixed in a high-energy ball mill with absolute ethanol as a dispersant at a speed of 600 rpm for 3 hours at a molar ratio of 1:12, and the ball-milled mixture was dried and placed in air Sintering at 1400° C. for 12 hours in an atmosphere, and cooling to room temperature to obtain HfO ₂ ·12Nb ₂ O ₅ material powder.

The HfO ₂ .12Nb ₂ O ₅ material obtained in Example 6 and the LiFePO ₄ positive electrode constitute a water-based secondary full battery. The mass ratio of the active material is negative electrode: positive electrode = 1:1.2, and the remaining conditions are the same as in Example 1, at 1.0-2.6 In the V voltage range, the reversible specific capacity can reach 150mAh/g in the first cycle at a current density of 0.1C, and it still has a capacity retention rate of 90% after 1000 cycles at a current density of 1C.

Example 7

This embodiment provides the preparation method of Al ₂ O ₃ ·11Nb ₂ O ₅ material and its application in water-based secondary lithium battery.

Aluminum oxide and niobium pentoxide were mixed with 1:17 molar ratio in a high-energy ball mill with absolute ethanol as a dispersant at a speed of 600 rpm for 3 hours, and after the ball-milled mixture was dried, the In an argon atmosphere, sinter at 1200°C for 12 hours, and cool to room temperature to obtain Al ₂ O ₃ ·11Nb ₂ O ₅ material powder.

The Al ₂ O ₃ ·11Nb ₂ O ₅ material obtained in Example 7 and the Li ₂ MnO ₃ positive electrode constitute a water-based secondary full battery. The mass ratio of active materials is negative electrode: positive electrode = 1:1, and the remaining conditions are the same as in Example 1. In the voltage range of 1.0-3.2V, the reversible specific capacity can reach 180mAh/g in the first cycle at 0.1C current density, and the capacity retention rate is still 80% after 1000 cycles at 1C current density.

Example 8

This embodiment provides a preparation method of 2TiO ₂ ·5Nb ₂ O ₅ material and its application in water-based secondary lithium batteries.

Titanium dioxide and niobium pentoxide were ball milled and mixed for 3 hours at a speed of 600 rpm in a high-energy ball mill with anhydrous ethanol as a dispersant at a molar ratio of 2:5, and the ball-milled mixture was dried and then placed in an argon atmosphere. sintering at 1100°C for 12 hours and cooling to room temperature to obtain FeNb ₁₁ O ₂₉ material powder.

The 2TiO ₂ ·5Nb ₂ O ₅ material obtained in Example 8 and the positive electrode of LiNi _0.5 Co _0.2 Mn _0.3 O ₂ constitute an aqueous secondary full battery. The mass ratio of active materials is negative electrode: positive electrode = 1:1.5, and other conditions are the same as in the embodiment 1. In the voltage range of 1.0-3.2V, the reversible specific capacity can reach 173mAh/g in the first cycle at 0.1C current density, and the capacity retention rate is still 83% after 1000 cycles at 1C current density.

Through the above examples, the new water-based secondary lithium battery of the present invention uses a binary niobium-based oxide composite material as the negative electrode material and an excess of lithium manganate as the positive electrode, and the charge and discharge voltage is 1.0-2.8V in the first week. In the window, it is as high as 179mAh/g, and the cycle stability is good. The capacity retention rate of 100 cycles at a current density of 0.2C (1C=389mA/g) is above 88%, and the capacity retention rate of 1000 cycles at a current density of 1C More than 80%.

The present invention uses the binary niobium-based oxide composite material as the negative electrode material of the water-based secondary lithium battery, and when the capacity ratio with LiMn ₂ O ₄ is Q _N : Q _P =1:1.05, within the voltage window of 1.0-3.2V, The energy density is as high as 160Wh/kg, and the same positive electrode material is superior to the negative electrode material of the existing water-based secondary lithium battery.

The binary niobium-based oxide composite material is used as the negative electrode material of the aqueous secondary lithium battery, which has high energy density, good cycle stability, intrinsic safety, no pollution, simple preparation process, wide application, and can be applied It is suitable for portable energy storage equipment, power battery equipment and backup power supply with high safety requirements. At the same time, the preparation process of this material is simple, fully meets the requirements of modern mass production, and has great application prospects.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Protection scope, within the spirit and principles of the present invention, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present invention.

Claims (10)

1. A novel aqueous secondary lithium battery characterized by comprising: a positive electrode, a negative electrode, a separator and a mixed salt electrolyte;

the negative electrode material of the negative electrode comprises a binary niobium-based oxide composite material; the general formula of the binary niobium-based oxide composite material is as follows: xM _a O _b ·yNb ₂ O ₅ (ii) a Wherein x is more than or equal to 1 and less than or equal to 9, y is more than or equal to 1 and less than or equal to 9, a is more than or equal to 1 and less than or equal to 3, b is more than or equal to 1 and less than or equal to 5; m is selected from one or more of Mg, al, P, ti, V, zn, ge, zr and Hf; wherein M is _a O _b Width of band gap of>3.0eV, which is used for improving the hydrogen evolution overpotential at the cathode interface;

the mixed salt electrolyte specifically comprises a mixed salt electrolyte composed of an aqueous Li salt and at least one of an alkali metal ion salt and a large cation organic salt, wherein in the mixed salt electrolyte, the molar ratio of the aqueous Li salt to the total amount of the alkali metal ion salt and the large cation organic salt is not less than 1.

2. The novel water-based secondary lithium battery as claimed in claim 1, wherein the positive electrode material of the positive electrode comprises: liFePO ₄ 、LiCoO ₂ 、LiMn ₂ O ₄ 、LiNi _0.5 Mn _1.5 O ₄ 、LiNi _0.6 Co _0.2 Mn _0.2 O ₂ 、LiNi _1/3 Co _1/3 Mn _1/3 O ₂ 、LiNi _0.8 Co _0.1 Mn _0.1 O ₂ 、LiNi _0.5 Co _0.2 Mn _0.3 O ₂ 、LiNi _0.8 Co _0.15 Al _0.05 O ₂ 、Li ₂ CoMnO ₄ 、Li ₂ MnO ₃ One or more of the following;

the diaphragm is any one of glass fiber, polypropylene diaphragm, non-woven fabric diaphragm, polyethylene diaphragm or polytetrafluoroethylene diaphragm.

3. The novel water-based secondary lithium battery as claimed in claim 1, wherein the water-based Li salt includes: liPF (lithium ion particle Filter) ₆ 、LiBF ₄ 、LiNO ₃ 、LiCl、LiClO ₄ 、Li ₂ SO ₄ One or more of LiAc, liTFSI, liOTF, liFSI and LiBETI;

the alkali metal ion salt comprises a Na salt and/or a K salt;

the Na salt comprises: naPF ₆ 、NaBF ₄ 、NaNO ₃ 、NaCl、NaClO ₄ 、Na ₂ SO ₄ One or more of sodium acetate NaAc, naTFSI, naOTF, naFSI and NaBETI;

said K salt comprises KPF ₆ 、KBF ₄ 、KNO ₃ 、KCl、KClO ₄ 、K ₂ SO ₄ One or more of KAc, KTFSI, KOTF, KFSI and KBETI;

cations in the macro-cation organic salt include one or more combinations of imidazolium, pyridinium, pyrrolium, piperidinium, morpholinium, quaternary ammonium, quaternary phosphonium, or ternary sulfonium ions, and anions include: cl ^- 、Br ^- 、I ^- 、PF ₆ ^- 、BF ₄ ^- 、CN ^- 、SCN ^- 、[N(CF ₃ SO ₂ ) ₂ ] ^- 、[N(CN) ₂ ] ^- One or more of the following;

in the mixed salt electrolyte, the molar ratio of the aqueous Li salt to the total amount of the alkali metal ion salt and the large cation organic salt is 1.

4. The novel aqueous secondary lithium battery according to claim 1, wherein the positive electrode and/or the negative electrode further comprises a current collector; the current collector specifically comprises any one of titanium, copper, platinum, nickel, gold, tungsten, molybdenum, tantalum and carbon, and is in the form of one of foam, mesh, sheet, carbon fiber cloth or pyrolytic graphite sheet.

5. The novel aqueous secondary lithium battery according to claim 1, wherein the positive electrode and/or the negative electrode further comprises a binder and a conductive additive;

the adhesive comprises: one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), acrylamide-acrylate copolymer, sodium alginate and beta-cyclodextrin are mixed;

the conductive additive includes: graphene, acetylene black, ketjen black, super P, carbon nanotubes, carbon fibers, BP2000, vulcan XC, or Denka.

6. A negative electrode material for a novel aqueous secondary lithium battery according to any one of claims 1 to 5, wherein the negative electrode material comprises a binary niobium-based oxide composite;

the general formula of the binary niobium-based oxide composite material is as follows: xM _a O _b ·yNb ₂ O ₅ (ii) a Wherein x is more than or equal to 1 and less than or equal to 9, y is more than or equal to 1 and less than or equal to 9, a is more than or equal to 1 and less than or equal to 3, and b is more than or equal to 1 and less than or equal to 5; m is selected from one or more of Mg, al, P, ti, V, zn, ge, zr and Hf; wherein, M _a O _b Width of band gap of>3.0eV, to increase the hydrogen evolution overpotential at the cathode interface.

7. The negative electrode material for a novel aqueous secondary lithium battery as claimed in claim 6, wherein the binary niobium-based oxide composite has a shear-ReO of the m x n x ∞ type ₃ The structure is shown in the specification, wherein m and n are positive integers.

8. A method for preparing the negative electrode material of claim 6 or 7, comprising:

mixing an M source and an Nb source in a required stoichiometric ratio by a solid phase ball milling method or a sol-gel method, and sintering in air or inert gas atmosphere to obtain a binary niobium-based oxide composite material xM _a O _b ·yNb ₂ O ₅ Namely the negative electrode material;

wherein the sintering temperature is 500-1400 ℃, and the sintering time is 1-72 hours.

9. The method according to claim 8, wherein the M source is an oxide of any one or more of Mg, al, P, ti, V, zn, ge, zr and Hf, or a substance containing an oxide of any one or more of Mg, al, P, ti, V, zn, ge, zr and Hf after decomposition and oxidation.

10. Use of a novel aqueous secondary lithium battery according to any one of claims 1 to 5, characterized in that it is used in power batteries for electric vehicles, in energy storage power stations, in power grid energy storage, in portable electronic devices, in aviation reserve power supplies, in submarine reserve power supplies or in aerospace reserve power supplies.

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