A lithium sodium titanium phosphate anode material and an aqueous lithium-iodine battery based thereon

Abstract

This invention provides a lithium titanium dioxide sodium phosphate anode material and an aqueous lithium-iodine battery based thereon, belonging to the field of secondary battery technology. The chemical formula of the lithium titanium dioxide sodium phosphate anode material is Li. x Na y Ti2(PO4)3, where 0

Description

Technical Field

[0001] This invention relates to the field of secondary battery technology, specifically to a lithium titanium sodium phosphate anode material and an aqueous lithium-iodine battery based thereon. Background Technology

[0002] With the rapid development of the global economy and the continuous rise in energy demand, the contradiction between energy supply and demand has become increasingly prominent, while environmental pollution problems are also becoming increasingly severe. Against this backdrop, efficient, green, and sustainable energy storage technologies have gradually become a key area of ​​scientific research. Especially in fields such as new energy transportation, renewable energy power generation, and smart grids, the demand for high-performance energy storage devices is particularly urgent. While existing lithium-ion batteries have high energy density, their high production costs, insufficient safety, and potential environmental hazards have led the research and industrial communities to seek safer, more environmentally friendly, and economically viable alternatives.

[0003] As a new type of energy storage system, aqueous batteries use water-based electrolytes to replace the organic electrolytes in traditional lithium-ion batteries, which not only significantly reduces production costs but also shows great advantages in terms of safety and environmental protection. In particular, aqueous lithium-iodine batteries utilize the reversible redox reaction between lithium and iodine to achieve energy storage and release, exhibiting good cycle stability and high operational safety. This characteristic makes them highly promising for applications in new energy vehicles, renewable energy storage systems, and large-scale power grids. Compared with traditional lithium-ion batteries, aqueous lithium-iodine batteries exhibit superior performance in the following aspects: (1) Improved safety: Using water as an electrolyte avoids the risk of combustion and explosion caused by leakage of organic electrolytes, improving the safety of the system; (2) Environmental protection and sustainability: Aqueous systems reduce dependence on harmful chemicals, which is conducive to achieving green production; (3) Reduced production costs: Aqueous electrolytes are inexpensive, the production process is simple, and they are easy to scale up.

[0004] However, despite the many advantages shown by aqueous lithium-iodine batteries, their practical application still faces a series of technical challenges that urgently need to be addressed: (1) High solubility and reactivity of iodine: Iodine has high solubility and reactivity in aqueous solution, which easily leads to iodine loss and battery capacity decay during discharge. This makes the battery performance unstable during cycling. (2) The impact of the "shuttle effect": During charging and discharging, dissolved iodine may migrate in the electrolyte, forming the so-called "shuttle effect", which leads to the loss of active materials and causes the battery capacity to gradually decrease. (3) Improvement of rate performance and cycle life: Although aqueous lithium-iodine batteries have good initial capacity, their rate performance and long-term cycle stability still need to be further improved to meet the needs of high-power equipment and long-term use scenarios.

[0005] In view of the above problems, the prior art has proposed various optimization strategies: (I) Stable iodine-loaded materials: By loading iodine on stable porous carbon materials, metal-organic frameworks (MOFs), or other nanostructured carriers, the thermodynamic stability and electrochemical properties of iodine can be effectively improved. (II) Construction of ion-selective membranes: Adding ion-selective membranes to the battery structure helps to suppress the shuttle effect and reduce the loss of active substances. (III) Optimization of electrolyte composition: By regulating the chemical composition of the electrolyte, the stability and ion conductivity of the system are improved to enhance the overall performance of the battery. (IV) Exploration of new electrode materials and battery structures: Adopting new anode materials and innovative battery designs further improves their rate performance and cycle life. However, in actual implementation of the above optimization strategies, the assembled aqueous lithium-iodine batteries still cannot simultaneously meet the requirements of high safety, good cycle performance, high capacity retention, and excellent rate performance. Summary of the Invention

[0006] Aiming at the deficiencies of the above prior art, the present invention provides a lithium sodium titanium phosphate anode material and an aqueous lithium-iodine battery based on it. The aqueous lithium-iodine battery assembled by the present invention has excellent electrochemical performance, cycle stability, and safety.

[0007] To achieve the above object, the specific technical solutions of the present invention are as follows:

[0008] In the first aspect, the present invention provides a lithium sodium titanium phosphate anode material with the chemical formula Li x Na y Ti2(PO4)3, where 0 < x ≤ 1 and y is (1 - x).

[0009] Preferably, the lithium sodium titanium phosphate anode material has a NASICON-type structure.

[0010] In the second aspect, the present invention provides a preparation method of the lithium sodium titanium phosphate, including the following steps:

[0011] (1) Add a lithium source, a titanium source, a phosphate, a sodium source, and a carbon source into a ball-milling solvent to obtain a raw material mixture;

[0012] (2) Grind the raw material mixture into a precursor solution with a particle size of 100 nm to 3 μm;

[0013] (3) Spray-dry the precursor solution to obtain a precursor powder with a size of 10 to 20 μm;

[0014] (4) Sinter the precursor powder under the protection of an inert gas and then screen it to obtain Li x Na y Ti2(PO4)3 microspheres.

[0015] The sodium titanium phosphate lithium anode material with a NASICON-type structure provided by this invention has a unique three-dimensional rigid framework structure that can significantly improve lithium-ion transport efficiency and enhance battery cycle stability; furthermore, by introducing Na... + This invention further broadens the diffusion channels of lithium ions, reduces lithium ion insertion resistance, and improves the rate performance and capacity retention of the battery. Furthermore, in the preparation process, this invention simplifies the material synthesis process by combining liquid-phase grinding and spray drying, achieving efficient and stable production, ensuring batch stability of the materials, guaranteeing the consistency of battery performance, and meeting the requirements of green production.

[0016] Preferably, in step (1), the lithium source is at least one of LiNO3, Li2SO4, LiOH, LiCl, Li2CO3, LiTFSI, Li3PO4, LiH2PO4, LiC2O4, CH3COOLi, and C5H7LiO2.

[0017] Preferably, in step (1), the titanium source is H2TiO3, Ti(SO4)2, TiCl4, or C. 16 H 36 At least one of O4Ti, TiO2, and NH4TiO3.

[0018] Preferably, in step (1), the phosphate is Na5P3O 10 At least one of NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, H3PO4, and Na2H2P2O7.

[0019] Preferably, in step (1), the sodium source is at least one of NaOH, CH3COONa·3H2O, NaNO3, Na2CO3, NaF, NaH2PO4·2H2O, Na2HPO4·2H2O, Na3PO4, and Na2H2P2O7.

[0020] Preferably, in step (1), the carbon source is porous carbon, activated carbon, or C6H4O. 12 O6 (glucose), C 12 H 22 O 11 At least one of the following: sucrose, soluble starch, PVA (polyvinyl alcohol), PVP (polyvinylpyrrolidone), PEG (polyethylene glycol), citric acid, PAN (polyacrylonitrile), phenolic resin, CNTs, acetylene black, and conductive carbon black.

[0021] Preferably, in step (1), the ball milling solvent is at least one of deionized water, methanol, ethanol, propanol, and isopropanol.

[0022] Preferably, in step (2), the grinding process is divided into coarse grinding and sand grinding, the coarse grinding time is 0.5~12 h; the sand grinding time is 1~24 h.

[0023] Preferably, in step (3), the spray drying equipment is one of a pressure spray dryer, a centrifugal spray dryer, or an airflow spray dryer.

[0024] Preferably, in step (3), the inlet air temperature of the spray dryer is 150~350 ℃ and the outlet air temperature is 60~100 ℃.

[0025] Preferably, in step (4), the sintering temperature is 600~900 ℃ and the sintering time is 4~24 h.

[0026] Thirdly, the present invention provides an aqueous lithium-iodine battery, comprising a negative electrode, a positive electrode, and an electrolyte, wherein the negative electrode active material is the lithium titanium sodium phosphate negative electrode material or the lithium titanium sodium phosphate negative electrode material prepared by the method described above, and the electrolyte contains lithium ions and iodine ions.

[0027] Preferably, the positive electrode active material is activated carbon.

[0028] This invention addresses the limitation of existing aqueous lithium-iodine batteries in simultaneously achieving good cycle performance, high capacity retention, high safety, and excellent rate performance. It develops a novel aqueous lithium-iodine battery using lithium sodium titanium phosphate as the negative electrode active material, activated carbon as the positive electrode active material, and an aqueous solution containing lithium and iodide ions as the electrolyte. This aqueous lithium-iodine battery exhibits excellent electrochemical performance, cycle stability, and safety, laying the foundation for the development of high-performance aqueous lithium-iodine batteries. Furthermore, by using an aqueous electrolyte instead of an organic electrolyte, the battery's safety and environmental friendliness are improved. Through rational design of electrode materials and adjustment of the electrolyte formulation, the shuttle effect of iodide ions in the electrolyte is reduced, effectively avoiding the loss of active materials and capacity decay, thus extending the battery's cycle life. This research will not only promote the widespread application of aqueous batteries in new energy vehicles and distributed energy storage systems but will also provide important technical support for energy transition and the achievement of carbon neutrality goals.

[0029] Fourthly, the present invention provides a method for assembling the aqueous lithium-iodine battery, comprising the following steps:

[0030] S1. Mix the sodium titanium phosphate lithium anode material, conductive carbon nanotubes, and polyvinylidene fluoride (PVDF) evenly, add a small amount of isopropanol, grind evenly, and then coat it onto the anode current collector, controlling the areal density to be 1~10 mg / cm³. 2 The negative electrode sheet is obtained by drying.

[0031] S2. Mix activated carbon, conductive agent, and polytetrafluoroethylene (PTFE), then add isopropanol and grind to obtain a uniform mixture; repeatedly roll and press the mixture into sheets with a thickness controlled at 15~30 µm, and dry to obtain the positive electrode sheet;

[0032] S3. Dissolve iodine salt and lithium salt in water and mix thoroughly to obtain an electrolyte;

[0033] S4. Place the positive electrode, glass fiber membrane, and negative electrode in that order, add electrolyte until the electrode and glass fiber membrane are wetted, seal the battery, and obtain an aqueous lithium-iodine battery.

[0034] Preferably, in step S1, the mass ratio of the sodium titanium phosphate lithium anode material, conductive carbon nanotubes, and polyvinylidene fluoride is 80:10:10.

[0035] Preferably, in step S1, the negative electrode current collector is one of titanium foil, stainless steel foil, nickel foam, and carbon paper.

[0036] Preferably, in steps S1 and S2, the drying temperature is 70~100 ℃ and the time is 6~24 h.

[0037] Preferably, in step S2, the conductive agent is a carbon-based material, which is at least one of conductive carbon black, Super P, conductive graphite, carbon nanotubes (CNTs), and graphene.

[0038] Preferably, the conductive graphite includes KS-5 or KS-6.

[0039] Preferably, in step S2, the mass ratio of the positive electrode active material, conductive agent, and PTFE is a:b:(100-ab), wherein 30≤a≤80, 10≤b≤50, and a+b≤90.

[0040] Preferably, in step S3, the iodized salt is at least one of LiI, HI, and MgI2.

[0041] Preferably, in step S3, the lithium salt is at least one selected from LiCl, LiNO3, Li2SO4, LiTFSi, LiI, C2F6LiNO4S2, and LiCF3SO3.

[0042] Preferably, in step S3, the concentration of iodine salt in the electrolyte is 0.1~0.5 mol / L.

[0043] Preferably, in step S3, the concentration of lithium salt in the electrolyte is 0.5~20 mol / L.

[0044] Compared with the prior art, the advantages of the present invention are:

[0045] (1) The sodium titanium phosphate lithium anode material with a NASICON structure provided by this invention has a unique three-dimensional rigid framework structure that can significantly improve the lithium-ion transport efficiency and enhance the cycle stability of the battery; by introducing Na + This further broadens the diffusion channels of lithium ions, reduces the resistance to lithium ion insertion, and improves the rate performance and capacity retention of the battery.

[0046] (2) The aqueous lithium-iodine battery provided by the present invention has the advantages of long cycle life, high rate performance and high safety, and is suitable for a variety of scenarios, as well as in distributed energy storage systems and smart grids. The high efficiency and stability of the aqueous lithium-iodine battery meet the requirements of high power and long-term use.

[0047] (3) The present invention uses an aqueous electrolyte containing lithium / iodine ions instead of an organic electrolyte, thereby avoiding the use of organic solvents, improving battery safety and reducing the risk of environmental pollution.

[0048] (4) The present invention adopts an innovative battery structure design and an efficient and controllable preparation process. The preparation process is simple, which can achieve efficient and stable production, ensure batch stability of materials, provide a guarantee for the consistency of battery performance, and meet the requirements of green production.

[0049] (5) By rationally designing electrode materials and adjusting electrolyte formulation, this invention reduces the shuttle effect of iodine ions in electrolyte, effectively avoids the problems of active material loss and capacity decay, and extends the cycle life of the battery. Attached Figure Description

[0050] Figure 1 Li in Example 1 0.5 Na 0.5 X-ray diffraction pattern of Ti2(PO4)3;

[0051] Figure 2 Li in Example 1 0.5 Na 0.5 SEM image of Ti2(PO4)3;

[0052] Figure 3 The aqueous lithium-iodine ion battery prepared in Example 1 was tested at 1 A g. -1 Charge-discharge curves at current density;

[0053] Figure 4 The aqueous lithium-iodine ion battery prepared in Example 1 was tested at 1 A g. -1 Cyclic performance at current density;

[0054] Figure 5 The aqueous lithium-iodine ion battery prepared for Comparative Example 1 was tested at 1 A g.-1 Cycling performance graph at a current density;

[0055] Figure 6 Cycling performance graph of the aqueous lithium iodide ion battery prepared in Comparative Example 2 at 1 A g -1 current density;

[0056] Figure 7 Cycling performance graph of the aqueous lithium iodide ion battery prepared in Comparative Example 3 at 1 A g -1 current density. Detailed implementation manners

[0057] The technical solutions of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without any creative work fall within the scope of protection of the present invention.

[0058] The present invention provides a lithium sodium titanium phosphate negative electrode material with the chemical formula Li x Na y Ti2(PO4)3, where 0 < x ≤ 1 and y is (1 - x).

[0059] The preparation method of the lithium sodium titanium phosphate includes the following steps:

[0060] (1) Add a lithium source, a titanium source, a phosphate, a sodium source and a carbon source into a ball milling solvent to obtain a raw material mixture solution;

[0061] (2) Grind the raw material mixture solution to a precursor solution with a particle size of 100 nm to 3 μm;

[0062] (3) Spray-dry the precursor solution to obtain a precursor powder with a size of 10 to 20 μm;

[0063] (4) Sinter the precursor powder under the protection of an inert gas and then screen it to obtain Li x Na y Ti2(PO4)3 microspheres.

[0064] In some examples, the lithium source is at least one of LiNO3, Li2SO4, LiOH, LiCl, Li2CO3, LiTFSI, Li3PO4, LiH2PO4, LiC2O4, CH3COOLi, C5H7LiO2; the titanium source is at least one of H2TiO3, Ti(SO4)2, TiCl4, C 16 H 36 O4Ti, TiO2, NH4TiO3; the phosphate is Na5P3O10 At least one of NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, H3PO4, and Na2H2P2O7; the sodium source is at least one of NaOH, CH3COONa·3H2O, NaNO3, Na2CO3, NaF, NaH2PO4·2H2O, Na2HPO4·2H2O, Na3PO4, and Na2H2P2O7; the carbon source is porous carbon, activated carbon, or C6H4PO4. 12 O6 (glucose), C 12 H 22 O 11 At least one of the following: sucrose, soluble starch, PVA (polyvinyl alcohol), PVP (polyvinylpyrrolidone), PEG (polyethylene glycol), citric acid, PAN (polyacrylonitrile), phenolic resin, CNTs, acetylene black, and conductive carbon black.

[0065] In some examples, the ball milling solvent is at least one of deionized water, methanol, ethanol, propanol, and isopropanol.

[0066] In some examples, the grinding process is divided into coarse grinding and sand grinding, with the coarse grinding time being 0.5 to 12 hours and the sand grinding time being 1 to 24 hours.

[0067] In some examples, the spray drying equipment is one of a pressure spray dryer, a centrifugal spray dryer, or an airflow spray dryer; in the following specific embodiments, the spray drying equipment is an airflow spray dryer.

[0068] In some examples, the inlet air temperature of the spray dryer is 150~350 ℃ and the outlet air temperature is 60~100 ℃.

[0069] In some examples, the sintering temperature is 600~900 ℃ and the sintering time is 4~24 h.

[0070] The present invention also provides an aqueous lithium-iodine battery, comprising a negative electrode, a positive electrode and an electrolyte, wherein the negative electrode active material is the aforementioned lithium titanium sodium phosphate negative electrode material or a lithium titanium sodium phosphate negative electrode material prepared by the aforementioned method, and the electrolyte contains lithium ions and iodine ions.

[0071] The assembly method of the aqueous lithium-iodine battery includes the following steps:

[0072] S1. Mix the sodium titanium phosphate lithium anode material, conductive carbon nanotubes, and polyvinylidene fluoride (PVDF) evenly, add a small amount of isopropanol, grind evenly, and then coat it onto the anode current collector, controlling the areal density to be 1~10 mg / cm³. 2 The negative electrode sheet is obtained by drying.

[0073] S2. Mix activated carbon, conductive agent, and polytetrafluoroethylene (PTFE), then add isopropanol and grind to obtain a uniform mixture; repeatedly roll and press the mixture into sheets with a thickness controlled at 15~30 µm, and dry to obtain the positive electrode sheet;

[0074] S3. Dissolve iodine salt and lithium salt in water and mix thoroughly to obtain an electrolyte;

[0075] S4. Place the positive electrode, glass fiber membrane, and negative electrode in that order, add electrolyte until the electrode and glass fiber membrane are wetted, seal the battery, and obtain an aqueous lithium-iodine battery.

[0076] In some examples, the negative current collector is one of titanium foil, stainless steel foil, nickel foam, and carbon paper.

[0077] In some examples, in steps S1 and S2, the drying temperature is 70~100 ℃ and the time is 6~24 h.

[0078] In some examples, in step S2, the conductive agent is a carbon-based material, which is at least one of conductive carbon black, Super P, conductive graphite, carbon nanotubes (CNTs), and graphene.

[0079] In some examples, the mass ratio of the positive electrode active material, conductive agent, and PTFE is a:b:(100-ab), where 30≤a≤80, 10≤b≤50, and a+b≤90.

[0080] In some examples, the iodine salt is at least one of LiI and MgI2; the lithium salt is at least one of LiCl, LiNO3, Li2SO4, LiTFSi, LiI, C2F6LiNO4S2, and LiCF3SO3.

[0081] In some examples, the concentration of iodine salt in the electrolyte is 0.1~0.5 mol / L; the concentration of lithium salt in the electrolyte is 0.5~20 mol / L.

[0082] Example 1

[0083] A water-based lithium-iodine battery

[0084] Preparation of lithium sodium titanium phosphate anode material:

[0085] (1) Add 3.405 kg tetrabutyl titanate, 0.105 kg lithium hydroxide monohydrate, 1.438 kg ammonium dihydrogen phosphate, 0.278 kg disodium dihydrogen pyrophosphate and 0.5 kg glucose to a mixed solvent of methanol and water to obtain a raw material mixture;

[0086] (2) The raw material mixture was placed in a ball mill for ball milling. The mixture was coarsely milled for 2 hours and sand milled for 6 hours to obtain the precursor solution.

[0087] (3) The precursor solution was spray-dried at an inlet air temperature of 205 ℃ and an outlet air temperature of 80 ℃ to obtain precursor powder;

[0088] (4) The precursor powder was sintered at 750 °C under a nitrogen atmosphere for 12 h, and the product Li was obtained by sieving. 0.5 Na 0.5 Ti2(PO4)3 micrometer spheres.

[0089] The Li prepared in this embodiment 0.5 Na 0.5 The X-ray diffraction results of Ti2(PO4)3 are as follows: Figure 1 As shown, by Figure 1 It can be seen that the product is Li. 0.5 Na 0.5 Ti2(PO4)3 with no obvious impurity peaks. Figure 2 For Li 0.5 Na 0.5 SEM images of Ti2(PO4)3, showing Li 0.5 Na 0.5 Ti2(PO4)3 has a granular structure with particle size distribution between 5 and 15 μm and uniform particle distribution.

[0090] Assembly of aqueous lithium-iodine batteries:

[0091] (1) Li 0.5 Na 0.5 Ti2(PO4)3, conductive carbon nanotubes, and PVDF are thoroughly mixed in a mass ratio of 80:10:10. A small amount of isopropanol is added, and the mixture is ground evenly. The resulting paste is then coated onto a carbon paper current collector with an areal density of 5 mg / cm³. 2 Dry in a 105 ℃ oven for 24 h, then cut into 10 mm electrode sheets for later use;

[0092] (2) Activated carbon, conductive carbon nanotubes and PTFE are ground and mixed evenly in isopropanol at a mass ratio of 70:10:20 to obtain a mixture; the mixture is placed in a roller press and repeatedly rolled and pressed into sheets with a thickness controlled at 22 µm. After pressing, the sheets are placed in an oven at 85℃ and dried for 24 h. They are then cut into electrode sheets with a diameter of 15 mm for later use.

[0093] (3) Using deionized water as a solvent, prepare a mixed electrolyte containing 0.25 mol / L lithium iodide and 7.5 mol / L lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) for later use;

[0094] (4) Assemble the 2025 button lithium-iodine battery by placing the positive electrode, glass fiber membrane, and negative electrode in that order, adding electrolyte until the electrode and glass fiber membrane are wetted, sealing the battery, and letting it stand for 1 hour before conducting a chemical performance test.

[0095] Figure 3 The aqueous lithium-iodine battery prepared in this embodiment was tested at 1 A g. -1 The charge-discharge curves at current density show that the specific discharge capacity of this aqueous lithium-iodine battery in the 0.3-1.5 V charge-discharge range is 98.3 mA h / g, and the charge-discharge efficiency is close to 100%, indicating that this aqueous lithium-iodine battery has good reversibility.

[0096] Figure 4 The aqueous lithium-iodine battery prepared in this embodiment was tested at 1 A g. -1 The battery cycle performance graph at current density shows that after 1000 cycles, its discharge specific capacity is 69.9 mA h / g, and the capacity retention rate is 71.1%. This result indicates that the aqueous lithium-iodine battery of the present invention has good reversibility and advantages of high power and long life.

[0097] Example 2

[0098] A water-based lithium-iodine battery

[0099] Preparation of lithium sodium titanium phosphate anode material:

[0100] (1) 3.405 kg tetrabutyl titanate, 0.148 kg lithium carbonate, 1.725 kg ammonium dihydrogen phosphate, 0.053 kg sodium carbonate, 0.2 kg glucose and 0.1 kg phenolic resin were added to a mixed solvent of isopropanol and water to obtain a raw material mixture.

[0101] (2) The raw material mixture was placed in a ball mill for ball milling. The mixture was coarsely milled for 1 hour and sand milled for 8 hours to obtain the precursor solution.

[0102] (3) The precursor solution was spray-dried at an inlet air temperature of 205 ℃ and an outlet air temperature of 75 ℃ to obtain precursor powder;

[0103] (4) The precursor powder was sintered at 650 °C under a nitrogen atmosphere for 12 h, and the product Li was obtained by sieving. 0.8 Na 0.2 Ti2(PO4)3 micrometer spheres.

[0104] Assembly of aqueous lithium-iodine batteries:

[0105] (1) Li 0.8 Na 0.2Ti2(PO4)3, conductive carbon nanotubes, and PVDF are thoroughly mixed in a mass ratio of 80:10:10. A small amount of isopropanol is added, and the mixture is ground evenly. The resulting paste is then coated onto a carbon paper current collector with an areal density of 5 mg / cm³. 2 Dry in a 100 ℃ oven for 24 h, then cut into 10 mm electrode sheets for later use;

[0106] (2) Grind and mix activated carbon, conductive carbon black and PTFE in isopropanol at a mass ratio of 60:20:20 to obtain a mixture; place the mixture in a roller press and repeatedly roll and press it into a sheet, with the thickness controlled at 22 µm. After pressing, place it in an oven at 105 °C and dry for 24 h. Cut it into electrode sheets with a diameter of 15 mm for later use.

[0107] (3) Using deionized water as a solvent, prepare a mixed electrolyte containing 0.1 mol / L magnesium iodide and 10 mol / L lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) for later use;

[0108] (4) Assemble the 2025 button lithium-iodine battery by placing the positive electrode, glass fiber membrane, and negative electrode in that order, adding electrolyte until the electrode and glass fiber membrane are wetted, sealing the battery, and letting it stand for 1 hour before conducting a chemical performance test.

[0109] Test results show that the aqueous lithium-iodine battery prepared in this embodiment achieves a performance of 1 A g. -1 At current density, its highest discharge specific capacity can reach 91.6 mA h / g. After 1000 cycles, its discharge specific capacity is 65.2 mA h / g, and the capacity retention rate is 71.2%.

[0110] Example 3

[0111] A water-based lithium-iodine battery

[0112] Preparation of lithium sodium titanium phosphate anode material:

[0113] (1) Add 0.799 kg of titanium dioxide, 0.306 kg of lithium acetate dihydrate, 1.98 kg of diammonium hydrogen phosphate, 0.082 kg of sodium hydroxide, 0.1 kg of sucrose, and 0.25 kg of PEG-8000 to an ethanol solvent to obtain a raw material mixture;

[0114] (2) The raw material mixture was placed in a ball mill for ball milling. The mixture was coarsely milled for 5 hours and sand milled for 4 hours to obtain the precursor solution.

[0115] (3) The precursor solution was spray-dried at an inlet air temperature of 205 ℃ and an outlet air temperature of 95 ℃ to obtain precursor powder;

[0116] (4) The precursor powder was sintered at 800 °C under a nitrogen atmosphere for 15 h, and the product Li was obtained by sieving. 0.6 Na 0.4 Ti2(PO4)3 micrometer spheres.

[0117] Assembly of aqueous lithium-iodine batteries:

[0118] (1) Li 0.6 Na 0.4 Ti2(PO4)3, conductive carbon nanotubes, and PVDF are thoroughly mixed in a mass ratio of 80:10:10. A small amount of isopropanol is added, and the mixture is ground evenly. The resulting paste is then coated onto a nickel current collector, with the areal density controlled at 5 mg / cm². 2 Dry in a 105 ℃ oven for 24 h, then cut into 10 mm electrode sheets for later use;

[0119] (2) Activated carbon, conductive carbon nanotubes and PTFE are ground and mixed evenly in isopropanol at a mass ratio of 65:20:15 to obtain a mixture; the mixture is placed in a roller press and repeatedly rolled and pressed into sheets with a thickness controlled at 22 µm. After pressing, the sheets are placed in an oven at 105℃ and dried for 24 h. They are then cut into electrode sheets with a diameter of 15 mm for later use.

[0120] (3) Using deionized water as a solvent, prepare a mixed electrolyte containing 0.2 mol / L lithium iodide and 2 mol / L lithium sulfate for later use;

[0121] (4) Assemble the 2025 button lithium-iodine battery by placing the positive electrode, glass fiber membrane, and negative electrode in that order, adding electrolyte until the electrode and glass fiber membrane are wetted, sealing the battery, and letting it stand for 1 hour before conducting a chemical performance test.

[0122] Test results show that the aqueous lithium-iodine battery prepared in this embodiment achieves a performance of 1 A g. -1 At current density, its highest discharge specific capacity can reach 83.4 mA h / g. After 1000 cycles, its discharge specific capacity is 60.2 mA h / g, and the capacity retention rate is 72.2%.

[0123] Example 4

[0124] A water-based lithium-iodine battery

[0125] Preparation of lithium sodium titanium phosphate anode material:

[0126] (1) Add 1.897 kg titanium tetrachloride, 0.468 kg lithium dihydrogen phosphate, 0.078 kg sodium dihydrogen phosphate dihydrate, 1.15 kg ammonium dihydrogen phosphate, 0.25 kg soluble starch and 0.1 kg PVA to deionized water to obtain a raw material mixture.

[0127] (2) The raw material mixture was placed in a ball mill for ball milling. The mixture was coarsely milled for 1 hour and sand milled for 8 hours to obtain the precursor solution.

[0128] (3) The precursor solution was spray-dried at an inlet air temperature of 205 ℃ and an outlet air temperature of 80 ℃ to obtain precursor powder;

[0129] (4) The precursor powder was sintered at 700 °C under a nitrogen atmosphere for 20 h, and the product Li was obtained by sieving. 0.9 Na 0.1 Ti2(PO4)3 micrometer spheres.

[0130] Assembly of aqueous lithium-iodine batteries:

[0131] (1) Li 0.9 Na 0.1 Ti2(PO4)3, conductive carbon nanotubes, and PVDF are thoroughly mixed in a mass ratio of 80:10:10. A small amount of isopropanol is added, and the mixture is ground evenly. The resulting paste is then coated onto a carbon paper current collector, with the areal density controlled at 5 mg / cm³. 2 Dry in a 105 ℃ oven for 24 h, then cut into 10 mm electrode sheets for later use;

[0132] (2) Activated carbon, conductive carbon nanotubes and PTFE are ground and mixed evenly in isopropanol at a mass ratio of 65:20:15 to obtain a mixture; the mixture is placed in a roller press and repeatedly rolled and pressed into sheets with a thickness controlled at 20 µm. After pressing, the sheets are placed in an oven at 105℃ and dried for 24 h. They are then cut into electrode sheets with a diameter of 15 mm for later use.

[0133] (3) Using deionized water as a solvent, prepare a mixed electrolyte containing 0.1 mol / L hydroiodic acid and 2 mol / L lithium nitrate for later use;

[0134] (4) Assemble the 2025 button lithium-iodine battery by placing the positive electrode, glass fiber membrane, and negative electrode in that order, adding electrolyte until the electrode and glass fiber membrane are wetted, sealing the battery, and letting it stand for 1 hour before conducting a chemical performance test.

[0135] Test results show that the aqueous lithium-iodine battery prepared in this embodiment achieves a performance of 1 A g. -1 At current density, its highest discharge specific capacity can reach 86.2 mA h / g. After 1000 cycles, its discharge specific capacity is 61.8 mA h / g, with a capacity retention rate of 71.7%.

[0136] Example 5

[0137] A water-based lithium-iodine battery

[0138] Preparation of lithium sodium titanium phosphate anode material:

[0139] (1) Add 3.405 kg tetrabutyl titanate, 0.039 kg lithium phosphate, 0.219 kg sodium phosphate, 1.761 kg diammonium hydrogen phosphate, 0.25 kg glucose and 0.1 kg activated carbon to a mixed solvent of methanol and water to obtain a raw material mixture;

[0140] (2) The raw material mixture was placed in a ball mill for ball milling. The mixture was coarsely milled for 1 h and sand milled for 10 h to obtain the precursor solution.

[0141] (3) The precursor solution was spray-dried at an inlet air temperature of 205 ℃ and an outlet air temperature of 80 ℃ to obtain precursor powder;

[0142] (4) The precursor powder was sintered at 850 °C under a nitrogen atmosphere for 10 h, and the product Li was obtained by sieving. 0.2 Na 0.8 Ti2(PO4)3 micrometer spheres.

[0143] Assembly of aqueous lithium-iodine batteries:

[0144] (1) Li 0.2 Na 0.8 Ti2(PO4)3, conductive carbon nanotubes, and PVDF are thoroughly mixed in a mass ratio of 80:10:10. A small amount of isopropanol is added, and the mixture is ground evenly. The resulting paste is then coated onto a carbon paper current collector, with the areal density controlled at 5 mg / cm³. 2 Dry in a 105 ℃ oven for 24 h, then cut into 10 mm electrode sheets for later use;

[0145] (2) Activated carbon, conductive carbon nanotubes and PTFE are ground and mixed evenly in isopropanol at a mass ratio of 70:15:15 to obtain a mixture; the mixture is placed in a roller press and repeatedly rolled and pressed into sheets with a thickness controlled at 25 µm. After pressing, the sheets are placed in an oven at 105℃ and dried for 24 h. They are then cut into electrode sheets with a diameter of 15 mm for later use.

[0146] (3) Using deionized water as a solvent, prepare a mixed electrolyte containing 0.5 mol / L lithium iodide and 6 mol / L lithium sulfate for later use;

[0147] (4) Assemble the 2025 button lithium-iodine battery by placing the positive electrode, glass fiber membrane, and negative electrode in that order, adding electrolyte until the electrode and glass fiber membrane are wetted, sealing the battery, and letting it stand for 1 hour before conducting a chemical performance test.

[0148] Test results show that the aqueous lithium-iodine battery prepared in this embodiment achieves a performance of 1 A g. -1At current density, its highest discharge specific capacity can reach 85.8 mA h / g. After 1000 cycles, its discharge specific capacity is 63.5 mA h / g, and the capacity retention rate is 74.0%.

[0149] Example 6

[0150] A water-based lithium-iodine battery

[0151] Preparation of lithium sodium titanium phosphate anode material:

[0152] (1) Add 1.897 kg titanium tetrachloride, 0.021 kg lithium hydroxide monohydrate, 0.702 kg sodium dihydrogen phosphate dihydrate, 1.566 kg ammonium phosphate and 0.15 kg acetylene black to a mixed solvent of ethanol and water to obtain a raw material mixture;

[0153] (2) The raw material mixture was placed in a ball mill for ball milling. The mixture was coarsely milled for 5 hours and sand milled for 8 hours to obtain the precursor solution.

[0154] (3) The precursor solution was spray-dried at an inlet air temperature of 205 ℃ and an outlet air temperature of 75 ℃ to obtain precursor powder;

[0155] (4) The precursor powder was sintered at 700 °C under a nitrogen atmosphere for 18 h, and the product Li was obtained by sieving. 0.1 Na 0.9 Ti2(PO4)3 micrometer spheres.

[0156] Assembly of aqueous lithium-iodine batteries:

[0157] (1) Li 0.1 Na 0.9 Ti2(PO4)3, conductive carbon nanotubes, and PVDF are thoroughly mixed in a mass ratio of 80:10:10. A small amount of isopropanol is added, and the mixture is ground evenly. The resulting paste is then coated onto a carbon paper current collector, with the areal density controlled at 5 mg / cm³. 2 Dry in a 105 ℃ oven for 24 h, then cut into 10 mm electrode sheets for later use;

[0158] (2) Activated carbon, conductive carbon nanotubes and PTFE are ground and mixed evenly in isopropanol at a mass ratio of 55:25:20 to obtain a mixture; the mixture is placed in a roller press and repeatedly rolled and pressed into sheets with a thickness controlled at 22 µm. After pressing, the sheets are placed in an oven at 105℃ and dried for 24 h. They are then cut into electrode sheets with a diameter of 15 mm for later use.

[0159] (3) Use deionized water as a solvent to prepare lithium iodide with a concentration of 0.5 mol / L as an electrolyte for later use;

[0160] (4) Assemble the 2025 button lithium-iodine battery by placing the positive electrode, glass fiber membrane, and negative electrode in that order, adding electrolyte until the electrode and glass fiber membrane are wetted, sealing the battery, and letting it stand for 1 hour before conducting a chemical performance test.

[0161] Test results show that the aqueous lithium-iodine battery prepared in this embodiment achieves a performance of 1 A g. -1 At current density, its highest discharge specific capacity can reach 81.4 mA h / g. After 1000 cycles, its discharge specific capacity is 60.2 mA h / g, with a capacity retention rate of 73.9%.

[0162] Comparative Example 1

[0163] The Li prepared in Example 1 0.5 Na 0.5 Ti2(PO4)3 was used as the active material for the negative electrode of the battery, magnesium iodide solution was used as the electrolyte, and the battery was assembled according to the following method:

[0164] (1) Li 0.5 Na 0.5 Ti2(PO4)3, conductive carbon nanotubes, and PVDF are thoroughly mixed in a mass ratio of 80:10:20. A small amount of isopropanol is added, and the mixture is ground evenly. The resulting paste is then coated onto a carbon paper current collector, with the areal density controlled at 5 mg / cm³. 2 Dry in a 105 ℃ oven for 24 h, then cut into 10 mm electrode sheets for later use;

[0165] (2) Activated carbon, conductive carbon nanotubes and PTFE are ground and mixed evenly in isopropanol at a mass ratio of 70:10:20 to obtain a mixture; the mixture is placed in a roller press and repeatedly rolled and pressed into sheets with a thickness controlled at 22 µm. After pressing, the sheets are placed in an oven at 105℃ and dried for 24 h. They are then cut into electrode sheets with a diameter of 15 mm for later use.

[0166] (3) Use deionized water as a solvent to prepare magnesium iodide with a concentration of 0.25 mol / L as an electrolyte for later use;

[0167] (4) Assemble the 2025 button lithium-iodine battery by placing the positive electrode, glass fiber membrane, and negative electrode in that order, adding electrolyte until the electrode and glass fiber membrane are wetted, sealing the battery, and letting it stand for 1 hour before conducting a chemical performance test.

[0168] The battery prepared in this comparative example has a capacitance of 1 A g. -1 Battery cycle performance at current density, such as Figure 5 As shown. By Figure 5 It is known that the battery's maximum discharge specific capacity is only 25.2 mA h / g.

[0169] Comparative Example 2

[0170] The Li prepared in Example 2 0.8 Na 0.2 Ti2(PO4)3 was used as the active material for the negative electrode of the battery, and LTFSI solution was used as the electrolyte. The battery was assembled according to the following method:

[0171] (1) Li 0.8 Na 0.2 Ti2(PO4)3, conductive carbon nanotubes, and PVDF are thoroughly mixed in a mass ratio of 80:10:20. A small amount of isopropanol is added, and the mixture is ground evenly. The resulting paste is then coated onto a carbon paper current collector, with the areal density controlled at 5 mg / cm³. 2 Dry in a 105 ℃ oven for 24 h, then cut into 10 mm electrode sheets for later use;

[0172] (2) Activated carbon, conductive carbon nanotubes and PTFE are ground and mixed evenly in isopropanol at a mass ratio of 60:20:20 to obtain a mixture; the mixture is placed in a roller press and repeatedly rolled and pressed into sheets with a thickness controlled at 22 µm. After pressing, the sheets are placed in an oven at 105℃ and dried for 24 h. They are then cut into electrode sheets with a diameter of 15 mm for later use.

[0173] (3) Use deionized water as solvent to prepare LTFSI with a concentration of 5 mol / L as electrolyte for later use;

[0174] (4) Assemble the 2025 button lithium-iodine battery by placing the positive electrode, glass fiber membrane, and negative electrode in that order, adding electrolyte until the electrode and glass fiber membrane are wetted, sealing the battery, and letting it stand for 1 hour before conducting a chemical performance test.

[0175] The battery prepared in this comparative example was at 1 A g. -1 Battery cycle performance at current density, such as Figure 6 As shown. By Figure 6 It can be seen that the highest discharge specific capacity of this battery is only 40 mA h / g.

[0176] Comparative Example 3

[0177] The Li prepared in Example 3 0.6 Na 0.4 Ti2(PO4)3 was used as the active material for the negative electrode of the battery, and a mixed solution of lithium iodide and lithium bis(trifluoromethanesulfonyl)imide was used as the electrolyte. The battery was assembled according to the following method:

[0178] (1) Li 0.6 Na 0.4Ti2(PO4)3, conductive carbon nanotubes, and PVDF are thoroughly mixed in a mass ratio of 80:10:10. A small amount of isopropanol is added, and the mixture is ground evenly. The resulting paste is then coated onto a carbon paper current collector, with the areal density controlled at 5 mg / cm³. 2 Dry in a 105 ℃ oven for 24 h, then cut into 10 mm electrode sheets for later use;

[0179] (2) Activated carbon, conductive carbon nanotubes and PTFE are ground and mixed evenly in isopropanol at a mass ratio of 65:20:10 to obtain a mixture; the mixture is placed in a roller press and repeatedly rolled and pressed into sheets with a thickness controlled at 22 µm. After pressing, the sheets are placed in an oven at 105℃ and dried for 24 h. They are then cut into electrode sheets with a diameter of 15 mm for later use.

[0180] (3) Using deionized water as a solvent, prepare a mixed electrolyte containing 0.05 mol / L lithium iodide and 0.25 mol / L lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) for later use;

[0181] (4) Assemble the 2025 button lithium-iodine battery by placing the positive electrode, glass fiber membrane, and negative electrode in that order, adding electrolyte until the electrode and glass fiber membrane are wetted, sealing the battery, and letting it stand for 1 hour before conducting a chemical performance test.

[0182] The battery prepared in this comparative example was at 1 A g. -1 Battery cycle performance at current density, such as Figure 7 As shown. By Figure 7 It is known that the battery's maximum discharge specific capacity can reach 63.7 mA h / g, and after 150 cycles, its discharge specific capacity is only 43.4 mA h / g.

[0183] Comparative Example 4

[0184] The battery assembly steps are as follows, using lithium titanium phosphate as the active material for the negative electrode:

[0185] (1) LiTi2(PO4)3, conductive carbon nanotubes, and PVDF were thoroughly mixed in a mass ratio of 80:10:10. A small amount of isopropanol was added, and the mixture was ground evenly. The mixture was then coated onto a carbon paper current collector with an areal density of 5 mg / cm³. 2 Dry in a 105 ℃ oven for 24 hours, then cut into 10 mm electrode sheets for later use;

[0186] (2) Activated carbon, conductive carbon nanotubes and PTFE are ground and mixed evenly in isopropanol at a mass ratio of 70:10:20 to obtain a mixture; the mixture is placed in a roller press and repeatedly rolled and pressed into sheets with a thickness controlled at 22 µm. After pressing, the sheets are placed in an oven at 85℃ and dried for 24 h. They are then cut into electrode sheets with a diameter of 15 mm for later use.

[0187] (3) Using deionized water as a solvent, prepare a mixed electrolyte containing 0.25 mol / L lithium iodide and 7.5 mol / L lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) for later use;

[0188] (4) Assemble the 2025 button lithium-iodine battery by placing the positive electrode, glass fiber membrane, and negative electrode in that order, adding electrolyte until the electrode and glass fiber membrane are wetted, sealing the battery, and letting it stand for 1 hour before conducting a chemical performance test.

[0189] The battery prepared in this comparative example was at 1 A g. -1 The highest discharge specific capacity at current density is 65.2 mA h / g, and after 150 cycles, its discharge specific capacity is only 41.7 mA h / g.

[0190] Comparative Example 5

[0191] Using sodium titanium phosphate as the active material for the negative electrode, the battery assembly steps are as follows:

[0192] (1) NaTi2(PO4)3, conductive carbon nanotubes, and PVDF were thoroughly mixed in a mass ratio of 80:10:10. A small amount of isopropanol was added, and the mixture was ground evenly. The mixture was then coated onto a carbon paper current collector with an areal density of 5 mg / cm³. 2 Dry in a 105 ℃ oven for 24 hours, then cut into 10 mm electrode sheets for later use;

[0193] (2) Activated carbon, conductive carbon nanotubes and PTFE are ground and mixed evenly in isopropanol at a mass ratio of 70:10:20 to obtain a mixture; the mixture is placed in a roller press and repeatedly rolled and pressed into sheets with a thickness controlled at 22 µm. After pressing, the sheets are placed in an oven at 85℃ and dried for 24 h. They are then cut into electrode sheets with a diameter of 15 mm for later use.

[0194] (3) Using deionized water as a solvent, prepare a mixed electrolyte containing 0.25 mol / L lithium iodide and 7.5 mol / L lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) for later use;

[0195] (4) Assemble the 2025 button lithium-iodine battery by placing the positive electrode, glass fiber membrane, and negative electrode in that order, adding electrolyte until the electrode and glass fiber membrane are wetted, sealing the battery, and letting it stand for 1 hour before conducting a chemical performance test.

[0196] The battery prepared in this comparative example was at 1 A g. -1 The highest discharge specific capacity at current density is 68.5 mA h / g, and after 150 cycles, its discharge specific capacity is only 47.9 mA h / g.

[0197] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A lithium titanium phosphate sodium lithium anode material, characterized in that, The chemical formula is Li x Na y Ti2(PO4)3, where 0 < x ≤ 1 and y is (1 - x).

2. The lithium titanium phosphate anode material according to claim 1, characterized in that, The sodium titanium phosphate lithium anode material has a NASICON-type structure.

3. A method for preparing a lithium sodium titanium phosphate anode material, characterized in that, Includes the following steps: (1) Add lithium source, titanium source, phosphate, sodium source and carbon source to ball milling solvent to obtain raw material mixture; (2) Grind the raw material mixture into a precursor solution with a particle size of 100 nm to 3 μm; (3) Spray dry the precursor solution to obtain precursor powder with a size of 10~20 μm; (4) After sintering the precursor powder under inert gas protection, it is sieved to obtain Li. x Na y Ti2(PO4)3.

4. A method for preparing a lithium sodium titanium phosphate anode material according to claim 3, characterized in that, The lithium source is at least one selected from LiNO3, Li2SO4, LiOH, LiCl, Li2CO3, LiTFSI, Li3PO4, LiH2PO4, LiC2O4, CH3COOLi, and C5H7LiO2; the titanium source is H2TiO3, Ti(SO4)2, TiCl4, and C 16 H 36 At least one of O4Ti, TiO2, and NH4TiO3; the phosphate is Na5P3O 10 The sodium source is at least one of NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, H3PO4, and Na2H2P2O7; the sodium source is at least one of NaOH, CH3COONa·3H2O, NaNO3, Na2CO3, NaF, NaH2PO4·2H2O, Na2HPO4·2H2O, Na3PO4, and Na2H2P2O7; the carbon source is at least one of porous carbon, activated carbon, glucose, sucrose, soluble starch, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene glycol, citric acid, polyacrylonitrile, phenolic resin, carbon nanotubes, acetylene black, and conductive carbon black.

5. A method for preparing a sodium titanium phosphate lithium anode material according to claim 3, characterized in that, The grinding process is divided into coarse grinding and sand grinding. The coarse grinding time is 0.5~12 h, and the sand grinding time is 1~24 h.

6. A method for preparing a sodium titanium phosphate lithium anode material according to claim 3, characterized in that, The inlet air temperature of the spray dryer is 150~350 ℃, and the outlet air temperature is 60~100 ℃.

7. A method for preparing a sodium titanium phosphate lithium anode material according to claim 3, characterized in that, The sintering temperature is 600~900 ℃, and the sintering time is 4~24 h.

8. An aqueous lithium-iodine battery, comprising a negative electrode, a positive electrode, and an electrolyte, characterized in that, The negative electrode active material includes the lithium sodium titanium phosphate negative electrode material as described in claim 1 or 2, or the lithium sodium titanium phosphate negative electrode material prepared by the method described in any one of claims 3 to 7, wherein the electrolyte contains lithium ions and iodine ions.

9. A method for assembling an aqueous lithium-iodine battery as described in claim 8, characterized in that, Includes the following steps: S1. Mix sodium titanium phosphate lithium anode material, conductive carbon nanotubes, and polyvinylidene fluoride evenly, add isopropanol, grind evenly, coat it on the anode current collector, and dry to obtain the anode sheet. S2. Mix activated carbon, conductive agent, and polytetrafluoroethylene, then add isopropanol and grind to obtain a homogeneous mixture; repeatedly roll and press the mixture into sheets, and dry to obtain a positive electrode sheet; S3. Dissolve iodine salt and lithium salt in water and mix thoroughly to obtain an electrolyte; S4. Place the positive electrode, glass fiber membrane, and negative electrode in that order, add electrolyte until the electrode and glass fiber membrane are wetted, seal the battery, and obtain an aqueous lithium-iodine battery.

10. The assembly method of an aqueous lithium-iodine battery according to claim 9, characterized in that, The concentration of iodine salt in the electrolyte is 0.1~0.5 mol / L; the concentration of lithium salt in the electrolyte is 0.5~20 mol / L.

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