Aqueous battery negative electrode material and application

Abstract

The embodiment of the invention relates to an aqueous battery negative electrode material and application. The negative electrode material of the aqueous battery is micron-sized titanium dioxide; electronegativity of oxygen atoms in molecules of micron-sized titanium dioxide attracts electrons of hydrogen atoms in water molecules, electronegativity of oxygen atoms in water molecules attracts electrons of titanium atoms in micron-sized titanium dioxide, and therefore sites where water molecules are combined with the surface of micron-sized titanium dioxide are generated on the surface of micron-sized titanium dioxide. Hydrogen atoms and oxygen atoms of water molecules and oxygen atoms and titanium atoms on the surface of the micron titanium dioxide form charge transfer; in addition, under the hydrogen bond action of water molecules, the water molecules adsorbed on the surface of the micron titanium dioxide form a network structure; through charge transfer and a network structure, the micron-sized titanium dioxide has higher surface energy and mechanical stability when being used as an aqueous battery negative electrode material to be in contact with water molecules in an electrolyte.

Description

Technical Field

[0001] The present invention relates to the technical field of negative electrode materials for aqueous batteries, and particularly to a negative electrode material for an aqueous battery and its application. Background Art

[0002] In lithium-ion batteries, the mechanical properties of the negative electrode material are crucial for the electrochemical properties of the material. The mechanical properties of the material are affected by the following factors: (1) The particle size of the negative electrode. Under the action of an electric field, lithium ions migrate within the negative electrode material, and this migration causes stress generation. The stress causes the particles of the material to break. A negative electrode material with a small particle size will have a smaller ion diffusion channel and lithium ion diffusion coefficient, thereby reducing the stress accumulation caused by lithium ion migration. (2) The surface properties of the negative electrode material. The surface properties of the negative electrode material, such as the active sites on the negative electrode surface, can affect the interaction between the material and the electrolyte, thereby affecting the surface energy of the negative electrode material. A high surface energy can improve the mechanical properties of the material. (3) The preparation process and testing methods of the negative electrode material. By optimizing the preparation process and testing methods of the negative electrode material, it is helpful to improve the mechanical properties of the material.

[0003] Micron-scale materials have attracted extensive attention due to their low production cost and high compaction density. At the same time, sub-micron-scale materials have also been reported to be able to inhibit the occurrence of side reactions. However, due to the volume expansion of the material, the coexistence of multiple phases in a single particle, and the gradient concentration distribution of lithium ions in the negative electrode material, micron-scale materials will encounter serious mechanical problems during the battery cycling process, thereby affecting the performance of the material.

[0004] Nanomaterials have strong properties of resisting mechanical fragmentation due to their shorter lithium ion diffusion channels and higher surface energy. The solutions of nanomaterials proposed in the prior art include one-dimensional nanowires, hollow nanomaterials, nanotubes, and porous materials, etc.

[0005] However, nanomaterials also have many disadvantages, such as complex preparation processes, high costs, and low compaction density. At the same time, due to the high specific surface area of nanomaterials, more active sites are provided compared to micron-scale materials, but too many active sites will cause continuous side reactions and a continuously growing solid electrolyte interphase layer (SEI), resulting in a lower Coulombic efficiency of the battery system.

[0006] Therefore, how to improve the surface energy of the negative electrode material is the key to better utilizing micron-scale negative electrode materials. Summary of the Invention

[0007] The object of the present invention is to provide a negative electrode material for an aqueous battery and its application in view of the defects existing in the prior art. The negative electrode material for the aqueous battery proposed by the present invention is nano-titanium dioxide, which has unique properties in combination with an aqueous electrolyte, can significantly increase the surface energy of micron-sized titanium dioxide, improve the mechanical stability of micron-sized titanium dioxide during the battery cycle, and make it have better electrochemical reversibility.

[0008] To achieve the above object, in a first aspect, the present invention provides a negative electrode material for an aqueous battery, and the negative electrode material for the aqueous battery is micron-sized titanium dioxide;

[0009] By the electronegativity of the oxygen atoms in the molecules of the micron-sized titanium dioxide attracting the electrons of the hydrogen atoms in the water molecules, and the electronegativity of the oxygen atoms in the water molecules attracting the electrons of the titanium atoms in the micron-sized titanium dioxide, binding sites for the water molecules to bind to the surface of the micron-sized titanium dioxide are generated on the surface of the micron-sized titanium dioxide, so that the hydrogen atoms and oxygen atoms of the water molecules form charge transfer with the oxygen atoms and titanium atoms on the surface of the micron-sized titanium dioxide; and, under the action of the hydrogen bonds of the water molecules, the water molecules adsorbed on the surface of the micron-sized titanium dioxide form a network structure; through the charge transfer and the network structure, when the micron-sized titanium dioxide is used as the negative electrode material for the aqueous battery and contacts with the water molecules in the electrolyte, it has higher surface energy and mechanical stability. Preferably, the particle size of the micron-sized titanium dioxide is 0.1 μm - 10 μm.

[0010] Preferably, the crystal forms of the micron-sized titanium dioxide include: rutile phase (rutile, P42 / mnm), anatase phase (anatase, I41 / amd), brookite phase (brookite, Pbca), TiO2B (bronze, C2 / m), TiO2R (ramsdellite, Pbnm), TiO2H (hollandite, I4 / m), TiO2 II (columbite, Pbcn), TiO2 III (baddeleyite, P21 / c), or one or more of them.

[0011] In a second aspect, an embodiment of the present invention provides a negative electrode of an aqueous battery, including the negative electrode material for the aqueous battery described in the first aspect above.

[0012] In a third aspect, an embodiment of the present invention provides an aqueous battery, including the negative electrode material for the aqueous battery and an aqueous electrolyte described in the first aspect above.

[0013] Preferably, the aqueous electrolyte of the aqueous battery is an aqueous solution composed of a metal salt AX that is stable in water;

[0014] In the metal salt AX, A is a cation, including alkali metal ions, alkaline earth metal ions, Zn 2+or Al 3+ and one or more of the following; X is an anion, including NO3 - , SO4 2- , Cl - , Br - , PO4 3- , CO3 2- , CH3COO - , CF3SO3 - , TFSI - , FSI - , BETI - , BF4 - and one or more of the following.

[0015] Preferably, the positive electrode material of the aqueous battery is a lithium-containing positive electrode material.

[0016] Preferably, the aqueous battery specifically includes any one of an aqueous rechargeable aluminum battery, an aqueous lithium battery, an aqueous sodium battery, an aqueous potassium battery, an aqueous zinc battery, an aqueous magnesium battery, and an aqueous calcium battery.

[0017] The negative electrode material of the aqueous battery provided by the embodiment of the present invention is micron-sized titanium dioxide. By the electronegativity of the oxygen atoms in the molecules of the micron-sized titanium dioxide attracting the electrons of the hydrogen atoms in the water molecules, and the electronegativity of the oxygen atoms in the water molecules attracting the electrons of the titanium atoms in the micron titanium dioxide, binding sites where water molecules combine with the surface of the micron titanium dioxide are generated on the surface of the micron titanium dioxide, so that the hydrogen atoms and oxygen atoms of the water molecules form charge transfer with the oxygen atoms and titanium atoms on the surface of the micron titanium dioxide; and because the size of the water molecules is small, there are more binding sites that can combine with the surface of the micron titanium dioxide, and the total charge transfer amount is larger. Under the action of hydrogen bonds, the water molecules adsorbed on the surface of the micron titanium dioxide will form a tight network structure, and this network structure will be similar to forming a protective "glue" coating on the surface of the micron titanium dioxide. Through the charge transfer and the network structure, when the micron-sized titanium dioxide is used as the negative electrode material of the aqueous battery and contacts the water molecules in the electrolyte, it has a higher surface energy, and at the same time has better mechanical stability during the battery cycle. In addition, because the micron-sized titanium dioxide has a lower specific surface area, it can effectively inhibit the hydrogen evolution side reaction in the aqueous electrolyte and significantly improve the cycle performance of the aqueous battery. Description of the Drawings

[0018] Figure 1 is a schematic diagram of the interaction between the micron-sized titanium dioxide provided by the embodiment of the present invention and water molecules and between the micron-sized titanium dioxide and organic molecules;

[0019] Figure 2 is the electrochemical performance of the micron-sized titanium dioxide in the aqueous electrolyte in Example 1 of the present invention and in the non-aqueous electrolyte in Comparative Example 1;

[0020] Figure 3 This is the transmission electron microscope image of micron-sized titanium dioxide after cycling in an aqueous electrolyte in Example 1 of the present invention;

[0021] Figure 4 This is the transmission electron microscope image of micron-sized titanium dioxide after cycling in a non-aqueous electrolyte in Comparative Example 1 of the present invention;

[0022] Figure 5 This is the curve of the change in surface energy of micron-sized titanium dioxide in water in Example 1 of the present invention and micron-sized titanium dioxide in an organic solvent in Comparative Example 1 along the X-axis direction;

[0023] Figure 6 This is the curve of the change in surface energy of micron-sized titanium dioxide in water in Example 1 of the present invention and micron-sized titanium dioxide in an organic solvent in Comparative Example 1 along the Y-axis direction;

[0024] Figure 7 This is the X-ray diffraction (XRD) pattern of the micron-sized titanium dioxide provided in Example 9 of the present invention and the nano-sized titanium dioxide provided in the comparative example of the present invention;

[0025] Figure 8 This is the cycling performance of the micron-sized titanium dioxide in Example 9 of the present invention and the nano-sized titanium dioxide in Comparative Example 9 in an aqueous electrolyte;

[0026] Figure 9 This is the comparison of the micron-sized titanium dioxide in Example 9 of the present invention and the nano-sized titanium dioxide in Comparative Example 9 in terms of specific surface area, hydrogen evolution rate, and total hydrogen evolution amount;

[0027] Figure 10 This is the first charge-discharge curve of the Ah-level soft-pack battery assembled with micron-sized titanium dioxide in Example 17 of the present invention;

[0028] Figure 11 This is the electrochemical performance curve of the Ah-level soft-pack battery in Example 17 of the present invention;

[0029] Figure 12 This is the energy storage performance curve of the Ah-level soft-pack battery in Example 17 of the present invention;

[0030] Figure 13 This is the first charge-discharge curve of the Ah-level soft-pack battery in Example 17 of the present invention at a rate of 0.27C;

[0031] Figure 14 This is the electrochemical performance curve of the Ah-level soft-pack battery in Example 17 of the present invention at a rate of 0.27C;

[0032] Figure 15It is the energy efficiency curve of the Ah-level soft-pack battery in Embodiment 17 of the present invention at a rate of 0.27C;

[0033] Figure 16 It is the first-week charge-discharge curve of the Ah-level soft-pack battery in Embodiment 17 of the present invention at -10°C;

[0034] Figure 17 It is the electrochemical performance of the Ah-level soft-pack battery in Embodiment 17 of the present invention at -10°C;

[0035] Figure 18 It is the first-week charge-discharge curve of the Ah-level soft-pack battery in Embodiment 17 of the present invention at 50°C;

[0036] Figure 19 It is the electrochemical performance of the Ah-level soft-pack battery in Embodiment 17 of the present invention at 50°C. Detailed implementation manners

[0037] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. 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 creative efforts shall fall within the protection scope of the present invention.

[0038] The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments.

[0039] The embodiment of the present invention provides a negative electrode material for an aqueous battery, which is micron-sized titanium dioxide with a particle size of 0.1 μm - 10 μm, and the crystal forms include: rutile (rutile, P42 / mnm), anatase (anatase, I41 / amd), brookite (brookite, Pbca), TiO2B (bronze, C2 / m), TiO2 R (ramsdellite, Pbnm), TiO2 H (hollandite, I4 / m), TiO2 II (columbite, Pbcn), TiO2 III (baddeleyite, P21 / c), or one or more of them.

[0040] The electronegativity of oxygen atoms in the molecules of the micron-sized titanium dioxide attracts the electrons of hydrogen atoms in water molecules, and the electronegativity of oxygen atoms in water molecules attracts the electrons of titanium atoms in the micron-sized titanium dioxide, thereby generating sites on the surface of the micron-sized titanium dioxide where water molecules bind to the surface of the micron-sized titanium dioxide, enabling the hydrogen and oxygen atoms of water molecules to form charge transfer with the oxygen and titanium atoms on the surface of the micron-sized titanium dioxide; moreover, under the action of the hydrogen bonds of water molecules, the water molecules adsorbed on the surface of the micron-sized titanium dioxide form a network structure; through the charge transfer and the network structure, when the micron-sized titanium dioxide is used as the negative electrode material of an aqueous battery and contacts the water molecules in the electrolyte, it has higher surface energy and mechanical stability. For the above reasons, the micron-sized titanium dioxide proposed in the present invention is suitable for use as the negative electrode material of an aqueous battery.

[0041] However, when the micron-sized titanium dioxide is used in combination with an organic electrolyte, the above technical effects cannot be achieved. This is because, although the organic solvent molecules can undergo partial electron transfer with the micron-sized titanium dioxide, due to the relatively large size of the organic molecules, some atoms in the organic molecules are far from the atoms on the surface of the micron-sized titanium dioxide, and there is a mismatch between some organic molecules and the atoms on the

[101] plane of the micron-sized titanium dioxide, resulting in a relatively small total charge transfer amount and a weak interaction. Therefore, the surface energy of the micron-sized titanium dioxide in the organic solvent is small, making its mechanical stability weak.

[0042] Figure 1 It is a schematic diagram of the interaction between the micron-sized titanium dioxide and water molecules and between the micron-sized titanium dioxide and the organic molecule dimethyl carbonate (DMC).

[0043] There is a strong charge transfer between the O in water and organic molecules and the Ti on the surface of the micron-sized TiO2. However, due to the relatively small size of water molecules, there are more sites that can bind to the surface of the micron-sized TiO2, resulting in a larger total charge transfer amount and a stronger interaction. In contrast, the size of the organic solvent is relatively large, so there are fewer interaction sites, resulting in a relatively small total charge transfer amount.

[0044] In addition, there is also a strong charge transfer between the H in water molecules and the O on the surface of the micron-sized TiO2. In contrast, only O in the organic solvent can undergo strong charge transfer with the surface of the TiO2. Due to the structural mismatch, the H in the organic solvent is far from the O on the surface of the TiO2, resulting in a small charge transfer amount.

[0045] Therefore, in combination with hydrogen bonding and the interactions between O and H in water molecules and Ti and O in micron-sized titanium dioxide, the water molecules adsorbed on the surface of micron-sized titanium dioxide will form a tight network structure, which will be similar to forming a protective "glue" coating on the surface of micron-sized titanium dioxide. Through the charge transfer and the network structure, micron-sized titanium dioxide has a higher surface energy when contacting water molecules in the electrolyte as the anode material of an aqueous battery.

[0046] The anode material of the aqueous battery provided by the embodiments of the present invention can be used as the anode of an aqueous battery and is used to assemble an aqueous battery with high voltage, high specific energy, long life, and low cost.

[0047] In a specific embodiment, the aqueous electrolyte of the aqueous battery is an aqueous solution composed of a metal salt AX that is stable in water; wherein, A is a cation, including alkali metal ions, alkaline earth metal ions, Zn 2+ or Al 3+ or one or more of them; X is an anion, including NO3 - , SO4 2- , Cl - , Br - , PO4 3- , CO3 2- , CH3COO - , CF3SO3 - , TFSI - , FSI - , BETI - , BF4 - or one or more of them.

[0048] In a specific embodiment, the cathode material for assembling the aqueous battery can be a lithium-containing cathode material, including but not limited to: LiMn2O4, LiFePO4, LiCoO2, LiNi x Co y Mn 1-x-y O2, LiNi x Co y Al 1-x-y O2, where x > 0, y > 0, and x + y < 1.

[0049] The aqueous battery capable of applying the anode material of the aqueous battery of the present invention may include: aqueous rechargeable aluminum batteries, alkali metal batteries, and alkaline earth metal batteries, such as aqueous lithium batteries, aqueous sodium batteries, aqueous potassium batteries, aqueous zinc batteries, aqueous magnesium batteries, aqueous calcium batteries, etc. Its application fields can include large-scale energy storage power stations, mobile power sources for portable devices, electric vehicles, and hybrid electric vehicles, etc.

[0050] To more clearly illustrate the purpose and advantages of the present invention, the present invention will be further described below in conjunction with embodiments. In addition, the embodiments described in the present invention are only partial embodiments. All other embodiments obtained by those skilled in the art without creative work based on the embodiments described in the present invention fall within the protection scope of the present invention. Additionally, it should be understood that these embodiments are only for more detailed description and should not be construed as limiting the present invention in any form, that is, it is not intended to limit the protection scope of the present invention.

[0051] Example 1

[0052] In this example, anatase-phase micron-sized titanium dioxide is used as the negative electrode material for the aqueous battery, and the particle size D50 is 0.2 μm. In this example, the formula of the aqueous electrolyte used to assemble the aqueous battery is 18 mol / kg of LiTFSI (18 m LiTFSI@H2O).

[0053] Comparative Example 1

[0054] In this comparative example, anatase-phase micron-sized titanium dioxide is used as the negative electrode material for the non-aqueous battery, and the particle size D50 is 0.2 μm. In this comparative example, the formula of the non-aqueous electrolyte is to dissolve 1 mol / L of LiClO4 in a mixed liquid of ethylene carbonate (EC) and DMC with a volume ratio of 1:1 (1 M LiClO4 in EC / DMC).

[0055] For the above Example 1 and Comparative Example 1, the battery is assembled with the positive electrode material LiMn2O4 respectively. Among them, the current collectors of the positive and negative electrodes are both aluminum foils.

[0056] Figure 2 The cycling performance of 0.2 μm anatase-phase TiO2 in aqueous electrolyte and non-aqueous electrolyte is shown. The rate of the first charge and discharge is 0.5C, and the charge and discharge voltage range is 0.8 - 2.5V. The first-cycle specific capacity of 0.2 μm TiO2 in aqueous electrolyte is 115.24 mAh / g, and the capacity retention rate after cycling 200 cycles at a rate of 0.5C is 76%. The first-cycle specific capacity of 0.2 μm anatase-phase TiO2 in non-aqueous electrolyte is 116.30 mAh / g, and the capacity retention rate after cycling 66 cycles at a rate of 0.5C is 49%. The specific results are recorded in Table 1.

[0057] It can be seen from the comparison that obvious performance differences occur for the same negative electrode material in different electrolyte systems. Through further characterization of 0.2 μm TiO2 cycled in the above two different electrolyte systems, it is found that the surface morphology of 0.2 μm TiO2 after cycling in aqueous electrolyte is intact, such as Figure 3As shown; while obvious cracks appeared on the surface of 0.2 μm TiO2 after cycling in the non-aqueous electrolyte, as Figure 4 shown.

[0058] It can be seen from the test of molecular dynamics simulation that when 0.2 μm TiO2 is in water or an organic solvent (EC + DMC, volume ratio 1:1), in the X-axis direction, when the tensile amount is the same, the energy required for 0.2 μm TiO2 in water is greater, while the energy required in the organic solvent is smaller, as Figure 5 shown, which indicates that 0.2 μm TiO2 is more difficult to break in the aqueous electrolyte. The same conclusion is obtained when stretching in the Y-axis direction, as Figure 6 shown.

[0059] Example 2

[0060] In this example, rutile titanium dioxide is used as the negative electrode material with a particle size D50 of 0.5 μm. In this example, the formula of the aqueous electrolyte is 16 mol / kg LiTFSI (16 m LiTFSI@H2O),

[0061] Comparative Example 2

[0062] In this comparative example, rutile titanium dioxide is used as the negative electrode material with a particle size D50 of 0.5 μm. In this comparative example, the formula of the non-aqueous electrolyte is 1 mol / L LiClO4 dissolved in a mixed liquid of EC and DMC with a volume ratio of 1:1 (1 M LiClO4 in EC / DMC).

[0063] For the above Example 2 and Comparative Example 2, battery assemblies are respectively assembled with the positive electrode material LiMn2O4. Among them, the current collectors of the positive and negative electrodes are both aluminum foils. The test conditions are the same as those in Example 1.

[0064] The initial specific capacity of 0.5 μm rutile TiO2 in the aqueous electrolyte is 119.58 mAh / g, and the capacity retention rate after cycling 200 weeks at a rate of 0.5C is 81%. The initial specific capacity of 0.5 μm rutile TiO2 in the non-aqueous electrolyte is 120.56 mAh / g, and the capacity retention rate after cycling 70 weeks at a rate of 0.5C is 54%. The specific results are recorded in Table 1.

[0065] Example 3

[0066] In this example, brookite titanium dioxide is used as the negative electrode material with a particle size D50 of 1 μm. In this example, the formula of the aqueous electrolyte is 17 mol / kg LiTFSI (17 m LiTFSI@H2O),

[0067] Comparative Example 3

[0068] In this comparative example, brookite titanium dioxide was used as the anode material with a particle size D50 of 1 μm. In this comparative example, the formulation of the non-aqueous electrolyte was 1 mol / L LiPF6 dissolved in a mixed liquid of EC and DMC with a volume ratio of 1:1 (1M LiPF6 in EC / DMC).

[0069] For the above Example 3 and Comparative Example 3, battery assemblies were respectively made with the cathode material LiMn2O4. Among them, the current collectors for both the anode and cathode were aluminum foils. The test conditions were the same as those in Example 1.

[0070] The initial specific capacity of 1 μm brookite titanium dioxide in the aqueous electrolyte was 110.23 mAh / g, and the capacity retention rate after 200 cycles at a rate of 0.5C was 83%. The initial specific capacity of 1 μm brookite titanium dioxide in the non-aqueous electrolyte was 109.78 mAh / g, and the capacity retention rate after 50 cycles at a rate of 0.5C was 39%. The specific results are recorded in Table 1.

[0071] Example 4

[0072] In this example, TiO2B was used as the anode material with a particle size D50 of 10 μm. In this example, the formulation of the aqueous electrolyte was 14 mol / kg LiTFSI (14m LiTFSI@H2O).

[0073] Comparative Example 4

[0074] In this comparative example, TiO2B was used as the anode material with a particle size D50 of 10 μm. In this comparative example, the formulation of the non-aqueous electrolyte was 1 mol / L LiPF6 dissolved in a mixed liquid of EC and DMC with a volume ratio of 1:1 (1M LiPF6 in EC / DMC).

[0075] For the above Example 4 and Comparative Example 4, battery assemblies were respectively made with the cathode material LiMn2O4. Among them, the current collectors for both the anode and cathode were aluminum foils. The test conditions were the same as those in Example 1.

[0076] The initial specific capacity of 10 μm TiO2B in the aqueous electrolyte was 108.57 mAh / g, and the capacity retention rate after 200 cycles at a rate of 0.5C was 86%. The initial specific capacity of 10 μm TiO2B in the non-aqueous electrolyte was 103.25 mAh / g, and the capacity retention rate after 70 cycles at a rate of 0.5C was 43%. The specific results are recorded in Table 1.

[0077] Example 5

[0078] In this embodiment, TiO2 R is used as the anode material with a particle size D50 of 2.1 μm. In this embodiment, the formula of the aqueous electrolyte is 12 mol / kg LiTFSI (12 m LiTFSI@H2O).

[0079] Comparative Example 5

[0080] In this comparative example, TiO2 R is used as the anode material with a particle size D50 of 2.1 μm. In this comparative example, the formula of the non-aqueous electrolyte is 1 mol / L LiPF6 dissolved in a mixed liquid of EC and DMC with a volume ratio of 1:1 (1 M LiPF6 in EC / DMC).

[0081] For the above-mentioned Example 5 and Comparative Example 5, the battery is assembled with the cathode material LiMn2O4 respectively. Among them, the current collectors of the positive and negative electrodes are both aluminum foils. The test conditions are the same as those in Example 1.

[0082] The initial specific capacity of 2.1 μm TiO2 R in the aqueous electrolyte is 116.95 mAh / g, and the capacity retention rate after cycling 200 times at a rate of 0.5C is 82%. The initial specific capacity of 2.1 μm TiO2 R in the non-aqueous electrolyte is 110.36 mAh / g, and the capacity retention rate after cycling 85 times at a rate of 0.5C is 33%. The specific results are recorded in Table 1.

[0083] Example 6

[0084] In this embodiment, TiO2 H is used as the anode material with a particle size D50 of 4.3 μm. In this embodiment, the formula of the aqueous electrolyte is 11 mol / kg LiTFSI (11 m LiTFSI@H2O).

[0085] Comparative Example 6

[0086] In this comparative example, TiO2 H is used as the anode material with a particle size D50 of 4.3 μm. In this comparative example, the formula of the non-aqueous electrolyte is 1 mol / L LiClO4 dissolved in a mixed liquid of EC and DMC with a volume ratio of 1:1 (1 M LiClO4 in EC / DMC).

[0087] For the above-mentioned Example 6 and Comparative Example 6, the battery is assembled with the cathode material LiMn2O4 respectively. Among them, the current collectors of the positive and negative electrodes are both aluminum foils. The test conditions are the same as those in Example 1.

[0088] The initial specific capacity of 4.3μm TiO2 H in aqueous electrolyte is 103.95mAh / g, and the capacity retention rate after 200 cycles at a rate of 0.5C is 84%. The initial specific capacity of 4.3μm TiO2 H in non-aqueous electrolyte is 102.36mAh / g, and the capacity retention rate after 90 cycles at a rate of 0.5C is 31%. The specific results are recorded in Table 1.

[0089] Example 7

[0090] In this example, TiO2 II is used as the anode material with a particle size D50 of 6.2μm. In this example, the formula of the aqueous electrolyte is 13mol / kg LiTFSI (13m LiTFSI@H2O).

[0091] Comparative Example 7

[0092] In this comparative example, TiO2 II is used as the anode material with a particle size D50 of 6.2μm. In this comparative example, the formula of the non-aqueous electrolyte is 1mol / L LiClO4 dissolved in a mixed liquid of EC and DMC with a volume ratio of 1:1 (1M LiClO4 in EC / DMC).

[0093] For the above Example 6 and Comparative Example 6, battery assemblies are respectively assembled with the cathode material LiMn2O4. Among them, the current collectors of the positive and negative electrodes are both aluminum foils. The test conditions are the same as those in Example 1.

[0094] The initial specific capacity of 6.2μm TiO2 II in aqueous electrolyte is 109.98mAh / g, and the capacity retention rate after 200 cycles at a rate of 0.5C is 82%. The initial specific capacity of 6.2μm TiO2 II in non-aqueous electrolyte is 101.59mAh / g, and the capacity retention rate after 80 cycles at a rate of 0.5C is 31%. The specific results are recorded in Table 1.

[0095] Example 8

[0096] In this example, TiO2 III is used as the anode material with a particle size D50 of 8.5μm. In this example, the formula of the aqueous electrolyte is 10mol / kg LiTFSI (10m LiTFSI@H2O).

[0097] Comparative Example 8

[0098] In this comparative example, TiO2 III is used as the anode material with a particle size D50 of 8.5μm. In this comparative example, the formula of the non-aqueous electrolyte is 1mol / L LiClO4 dissolved in a mixed liquid of EC and DMC with a volume ratio of 1:1 (1M LiClO4 in EC / DMC).

[0099] For the above-mentioned Example 6 and Comparative Example 6, lithium manganese oxide (LiMn2O4) was used as the cathode material to assemble the batteries. In this case, the current collectors for both the anode and the cathode were aluminum foils. The test conditions were the same as those in Example 1.

[0100] The initial specific capacity of 8.5 μm TiO2 III in the aqueous electrolyte was 112.69 mAh / g, and the capacity retention rate after 200 cycles at a rate of 0.5C was 82%. The initial specific capacity of 8.5 μm TiO2 III in the non-aqueous electrolyte was 115.74 mAh / g, and the capacity retention rate after 75 cycles at a rate of 0.5C was 55%. The specific results are recorded in Table 1.

[0101]

[0102] Table 1

[0103] It can be seen that the micron-sized titanium dioxide proposed in the present invention can work in an aqueous battery, which can increase the surface energy of the micron-sized titanium dioxide, improve the mechanical stability of the micron-sized titanium dioxide during the battery cycling process, and has better electrochemical reversibility and cycling performance compared to working in a battery using an organic solvent electrolyte.

[0104] Example 9

[0105] In this example, anatase-phase micron-sized titanium dioxide with a particle size D50 of 0.2 μm was used as the anode material for the aqueous battery.

[0106] Comparative Example 9

[0107] In this comparative example, anatase-phase nano-sized titanium dioxide with a particle size D50 of 5 nm was used as the anode material for the aqueous battery.

[0108] The XRD patterns of the anode materials for the aqueous batteries in Example 9 and Comparative Example 9 are as Figure 8 shown.

[0109] For the above-mentioned Example 9 and Comparative Example 9, aqueous batteries were assembled using lithium manganese oxide (LiMn2O4) as the cathode material. The formula of the aqueous electrolyte used was 18 mol / kg LiTFSI (18 m LiTFSI@H2O). In this case, the current collectors for both the anode and the cathode were aluminum foils. The test conditions were the same as those in Example 1.

[0110] The initial specific capacity of 0.2μm anatase TiO2 is 125.26 mAh / g, the initial Coulombic efficiency is 88.97%, the average Coulombic efficiency over 290 cycles is 98.7%, and the capacity retention rate after 290 cycles at 0.5C is 100%. The initial specific capacity of 5nm anatase TiO2 is 115.73 mAh / g, the initial Coulombic efficiency is 50.21%, the average Coulombic efficiency over 290 cycles is 94.43%, and the capacity retention rate after 290 cycles at 0.5C is 11.24%. The specific results are recorded in Table 2.

[0111] The specific surface area of 0.2μm anatase TiO2 is 10.165 m 2 / g, and the specific surface area of 5nm anatase TiO2 is 253.907 m 2 / g. Through in-situ electrochemical differential mass spectrometry testing, the total hydrogen evolution amount of 0.2μm anatase TiO2 is 3.6 μmol, and the maximum hydrogen evolution rate is 4.3 nmol·min -1 ·mg -1 . The total hydrogen evolution amount of 5nm TiO2 is 34.7 μmol, and the maximum hydrogen evolution rate is 66 nmol·min -1 ·mg -1 , as Figure 9 shown. From the total hydrogen evolution amount, it can be seen that the total hydrogen evolution amount in the anode of micron-sized anatase TiO2 is one order of magnitude less than that in the anode of nanometer-sized anatase TiO2, indicating that in the full cell with micron-sized anatase TiO2 anode, the reduction of active lithium in the cathode due to the hydrogen evolution side reaction is less than that in the full cell with nanometer-sized anatase TiO2 anode, making the full cell with micron-sized anatase TiO2 have better cycling performance.

[0112] Example 10

[0113] In this example, rutile-phase micron-sized titanium dioxide with a particle size D50 of 0.5μm is used as the anode material for the aqueous battery.

[0114] Comparative Example 10

[0115] In this comparative example, rutile-phase nanometer-sized titanium dioxide with a particle size D50 of 7nm is used as the anode material for the aqueous battery.

[0116] For the above Example 10 and Comparative Example 10, aqueous batteries are assembled with the cathode material LiMn2O4, and the formula of the aqueous electrolyte used is 16 mol / kg LiTFSI (16m LiTFSI@H2O). Among them, the current collectors for both the cathode and anode are aluminum foils. The test conditions are the same as in Example 1.

[0117] The initial specific capacity of 0.5 μm rutile TiO₂ is 120.62 mAh / g, the initial Coulombic efficiency is 89.76%, the average Coulombic efficiency after 300 cycles is 99.0%, and the capacity retention rate after 300 cycles at 0.5C is 98%. The initial specific capacity of 7 nm rutile TiO₂ is 118.24 mAh / g, the initial Coulombic efficiency is 47.21%, the average Coulombic efficiency after 300 cycles is 92.39%, and the capacity retention rate after 300 cycles at 0.5C is 18.37%. The specific results are recorded in Table 2.

[0118] Example 11

[0119] In this example, anatase-phase micron-sized titanium dioxide with a particle size D50 of 1 μm is used as the negative electrode material for the aqueous battery.

[0120] Comparative Example 11

[0121] In this comparative example, anatase-phase nano-sized titanium dioxide with a particle size D50 of 8 nm is used as the negative electrode material for the aqueous battery.

[0122] For the above Example 11 and Comparative Example 11, aqueous batteries are assembled with the positive electrode material LiMn₂O₄, and the formula of the aqueous electrolyte used is 17 mol / kg LiTFSI (17 m LiTFSI@H₂O). Among them, the current collectors for both the positive and negative electrodes are aluminum foils. The test conditions are the same as those in Example 1.

[0123] The initial specific capacity of 1 μm anatase-phase TiO₂ is 105.73 mAh / g, the initial Coulombic efficiency is 92.96%, the average Coulombic efficiency after 300 cycles is 99.2%, and the capacity retention rate after 300 cycles at 0.5C is 97%. The initial specific capacity of 8 nm anatase-phase TiO₂ is 108.43 mAh / g, the initial Coulombic efficiency is 53.12%, the average Coulombic efficiency after 300 cycles is 93.96%, and the capacity retention rate after 300 cycles at 0.5C is 19.64%. The specific results are recorded in Table 2.

[0124] Example 12

[0125] In this example, TiO₂ B with a particle size D50 of 10 μm is used as the negative electrode material for the aqueous battery.

[0126] Comparative Example 12

[0127] In this comparative example, TiO₂ B with a particle size D50 of 12 nm is used as the negative electrode material for the aqueous battery.

[0128] For the above-mentioned Example 12 and Comparative Example 12, aqueous batteries were assembled using the cathode material LiMn2O4, and the formula of the aqueous electrolyte used was 14 mol / kg LiTFSI (14 m LiTFSI@H2O). Among them, the current collectors of the positive and negative electrodes were both aluminum foils. The test conditions were the same as those in Example 1.

[0129] The initial specific capacity of 10 μm TiO2B was 101.73 mAh / g, the initial Coulombic efficiency was 95.96%, the average Coulombic efficiency over 300 cycles was 99.6%, and the capacity retention rate after 300 cycles at 0.5C was 95%. The initial specific capacity of 12 nm TiO2B was 110.43 mAh / g, the initial Coulombic efficiency was 63.12%, the average Coulombic efficiency over 300 cycles was 95.79%, and the capacity retention rate after 300 cycles at 0.5C was 23.46%. The specific results are recorded in Table 2.

[0130] Example 13

[0131] In this example, TiO2 R with a particle size D50 of 2.1 μm was used as the anode material for the aqueous battery.

[0132] Comparative Example 13

[0133] In this comparative example, TiO2 R with a particle size D50 of 9 nm was used as the anode material for the aqueous battery.

[0134] For the above-mentioned Example 13 and Comparative Example 13, aqueous batteries were assembled using the cathode material LiMn2O4, and the formula of the aqueous electrolyte used was 12 mol / kg LiTFSI (12 m LiTFSI@H2O). Among them, the current collectors of the positive and negative electrodes were both aluminum foils. The test conditions were the same as those in Example 1.

[0135] The initial specific capacity of 2.1 μm TiO2 R was 120.66 mAh / g, the initial Coulombic efficiency was 96.86%, the average Coulombic efficiency over 300 cycles was 99.54%, and the capacity retention rate after 300 cycles at 0.5C was 98.74%. The initial specific capacity of 9 nm TiO2 R was 118.59 mAh / g, the initial Coulombic efficiency was 59.21%, the average Coulombic efficiency over 300 cycles was 90.76%, and the capacity retention rate after 300 cycles at 0.5C was 14.23%. The specific results are recorded in Table 2.

[0136] Example 14

[0137] In this example, TiO2H with a particle size D50 of 4.3 μm was used as the anode material for the aqueous battery.

[0138] Comparative Example 14

[0139] In this comparative example, TiO2 H with a particle size D50 of 11 nm was used as the anode material for the aqueous battery.

[0140] For the above-mentioned Example 14 and Comparative Example 14, aqueous batteries were assembled with the cathode material LiMn2O4, and the formula of the aqueous electrolyte used was 11 mol / kg LiTFSI (11 m LiTFSI@H2O). Among them, the current collectors of both the positive and negative electrodes were aluminum foils. The test conditions were the same as those in Example 1.

[0141] The initial specific capacity of 4.3 μm TiO2 H was 106.98 mAh / g, the initial Coulombic efficiency was 95.86%, the average Coulombic efficiency over 300 cycles was 99.64%, and the capacity retention rate after 300 cycles at 0.5C was 99.34%. The initial specific capacity of 11 nm TiO2 H was 109.95 mAh / g, the initial Coulombic efficiency was 60.34%, the average Coulombic efficiency over 300 cycles was 93.87%, and the capacity retention rate after 300 cycles at 0.5C was 10.33%. The specific results are recorded in Table 2.

[0142] Example 15

[0143] In this example, TiO2 II with a particle size D50 of 6.2 μm was used as the anode material for the aqueous battery.

[0144] Comparative Example 15

[0145] In this comparative example, TiO2 II with a particle size D50 of 15 nm was used as the anode material for the aqueous battery.

[0146] For the above-mentioned Example 15 and Comparative Example 15, aqueous batteries were assembled with the cathode material LiMn2O4, and the formula of the aqueous electrolyte used was 13 mol / kg LiTFSI (13 m LiTFSI@H2O). Among them, the current collectors of both the positive and negative electrodes were aluminum foils. The test conditions were the same as those in Example 1.

[0147] The initial specific capacity of 6.2 μm TiO2 II was 116.89 mAh / g, the initial Coulombic efficiency was 93.79%, the average Coulombic efficiency over 300 cycles was 99.04%, and the capacity retention rate after 300 cycles at 0.5C was 97.43%. The initial specific capacity of 15 nm TiO2 II was 119.59 mAh / g, the initial Coulombic efficiency was 58.34%, the average Coulombic efficiency over 300 cycles was 94.97%, and the capacity retention rate after 300 cycles at 0.5C was 16.33%. The specific results are recorded in Table 2.

[0148] Example 16

[0149] In this example, TiO2 III with a particle size D50 of 8.5 μm was used as the anode material for the aqueous battery.

[0150] Comparative Example 16

[0151] In this comparative example, TiO2 III with a particle size D50 of 16 nm was used as the negative electrode material for the aqueous battery.

[0152] For the above-mentioned Example 16 and Comparative Example 16, aqueous batteries were assembled with the positive electrode material LiMn2O4, and the formula of the aqueous electrolyte used was 10 mol / kg LiTFSI (10 m LiTFSI@H2O). Among them, the current collectors for both the positive and negative electrodes were aluminum foils. The test conditions were the same as those in Example 1.

[0153] The initial specific capacity of 8.5 μm TiO2 III was 126.89 mAh / g, the initial Coulombic efficiency was 96.34%, the average Coulombic efficiency after 300 cycles was 99.74%, and the capacity retention rate after 300 cycles at 0.5C was 95.46%. The initial specific capacity of 16 nm TiO2 III was 119.86 mAh / g, the initial Coulombic efficiency was 60.59%, the average Coulombic efficiency after 300 cycles was 93.71%, and the capacity retention rate after 300 cycles at 0.5C was 10.85%. The specific results are recorded in Table 2.

[0154]

[0155] Table 2

[0156] It can be seen that the micron-sized titanium dioxide proposed in the present invention works in the aqueous battery and has a higher Coulombic efficiency and better cycling performance compared to the nano-sized titanium dioxide.

[0157] Example 17

[0158] In this example, anatase TiO2 was used as the negative electrode material with a particle size D50 of 0.2 μm, the positive electrode material was LiMn2O4, the current collectors for both the positive and negative electrodes were aluminum foils, and the electrolyte was 18 m LiTFSI to assemble an Ah-level soft-pack full battery. The Ah-level soft-pack battery had a charge-discharge voltage range of 0.8 - 2.5 V at a rate of 0.3C, and the released capacity was 1.153 Ah, and the energy density was 53 Wh / kg, as Figure 10 shown. The capacity retention rate of the battery after 1200 cycles at a rate of 1.45C was 71%, as Figure 11 shown. The results are recorded in Table 3. The voltage of the battery did not show obvious attenuation after standing for 23.5 days, as Figure 12 shown. The initial discharge capacity of this Ah-level soft-pack battery at a rate of 0.27C was 1.023 Ah, and the energy density was 52 Wh / kg, as Figure 13 shown. The capacity retention rate after 100 cycles was 82%, as Figure 14 shown. The energy efficiency of the battery at 0.27C was about 90%, as Figure 15As shown. The Ah-level battery can release a capacity of 0.6015 Ah at a rate of 0.07C in an environment of -10°C ( Figure 16 ), and the capacity has no attenuation after 150 cycles ( Figure 17 ). The Ah-level battery can release a capacity of 1.129 Ah at a rate of 1.43C in an environment of 50°C ( Figure 18 ), and the capacity retention rate is 67% after 85 cycles at a rate of 1.43C ( Figure 19 ).

[0159] Example 18

[0160] In this example, rutile-phase TiO2 is used as the negative electrode material with a particle size D50 of 0.5 μm, LiMn2O4 is used as the positive electrode material, aluminum foils are used as the current collectors for both the positive and negative electrodes, the electrolyte is 16 m LiTFSI, and an Ah-level soft-pack full battery is assembled. The Ah-level soft-pack battery has a charge-discharge voltage range of 0.8 - 2.5V at a rate of 0.3C, releases a capacity of 1.243 Ah, and has an energy density of 55 Wh / kg. The battery has a capacity retention rate of 73% after 1200 cycles at a rate of 1.52C, and the results are recorded in Table 3.

[0161] Example 19

[0162] In this example, brookite-phase TiO2 is used as the negative electrode material with a particle size D50 of 1 μm, LiMn2O4 is used as the positive electrode material, aluminum foils are used as the current collectors for both the positive and negative electrodes, the electrolyte is 17 m LiTFSI, and an Ah-level soft-pack full battery is assembled. The Ah-level soft-pack battery has a charge-discharge voltage range of 0.8 - 2.5V at a rate of 0.25C, releases a capacity of 1.356 Ah, and has an energy density of 59 Wh / kg. The battery has a capacity retention rate of 75% after 1300 cycles at a rate of 1.46C, and the results are recorded in Table 3.

[0163] Example 20

[0164] In this example, TiO2B is used as the negative electrode material with a particle size D50 of 10 μm, LiMn2O4 is used as the positive electrode material, aluminum foils are used as the current collectors for both the positive and negative electrodes, the electrolyte is 14 m LiTFSI, and an Ah-level soft-pack full battery is assembled. The Ah-level soft-pack battery has a charge-discharge voltage range of 0.8 - 2.5V at a rate of 0.29C, releases a capacity of 1.158 Ah, and has an energy density of 60 Wh / kg. The battery has a capacity retention rate of 71% after 1500 cycles at a rate of 1.52C, and the results are recorded in Table 3.

[0165] Example 21

[0166] In this example, TiO2 R is used as the anode material with a D50 particle size of 2.1 μm, LiMn2O4 is used as the cathode material, aluminum foils are used as the current collectors for both the anode and cathode, 13 m LiTFSI is used as the electrolyte, and an Ah-level soft-pack full cell is assembled. The Ah-level soft-pack cell has a charge-discharge voltage range of 0.8 - 2.5 V at a rate of 0.32C, releases a capacity of 1.426 Ah, and has an energy density of 59 Wh / kg. The cell has a capacity retention rate of 75% after 1000 cycles at a rate of 1.35C, and the results are recorded in Table 3.

[0167] Example 22

[0168] In this example, TiO2 H is used as the anode material with a D50 particle size of 4.3 μm, LiMn2O4 is used as the cathode material, aluminum foils are used as the current collectors for both the anode and cathode, 11 m LiTFSI is used as the electrolyte, and an Ah-level soft-pack full cell is assembled. The Ah-level soft-pack cell has a charge-discharge voltage range of 0.8 - 2.5 V at a rate of 0.35C, releases a capacity of 1.357 Ah, and has an energy density of 58 Wh / kg. The cell has a capacity retention rate of 70% after 1600 cycles at a rate of 1.45C, and the results are recorded in Table 3.

[0169] Example 23

[0170] In this example, TiO2 II is used as the anode material with a D50 particle size of 6.2 μm, LiMn2O4 is used as the cathode material, aluminum foils are used as the current collectors for both the anode and cathode, 13 m LiTFSI is used as the electrolyte, and an Ah-level soft-pack full cell is assembled. The Ah-level soft-pack cell has a charge-discharge voltage range of 0.8 - 2.5 V at a rate of 0.4C, releases a capacity of 1.532 Ah, and has an energy density of 55 Wh / kg. The cell has a capacity retention rate of 79% after 1300 cycles at a rate of 1.52C, and the results are recorded in Table 3.

[0171] Example 24

[0172] In this example, TiO2 III is used as the anode material with a D50 particle size of 8.5 μm, LiMn2O4 is used as the cathode material, aluminum foils are used as the current collectors for both the anode and cathode, 10 m LiTFSI is used as the electrolyte, and an Ah-level soft-pack full cell is assembled. The Ah-level soft-pack cell releases a capacity of 1.426 Ah at a rate of 0.5C and has an energy density of 59 Wh / kg. The cell has a capacity retention rate of 74% after 1500 cycles at a rate of 1.36C, and the results are recorded in Table 3

[0173]

[0174] Table 3

[0175] The present invention realizes the use of micron-sized titanium dioxide in an aqueous battery system, highlights its technical advantages, has a wide applicable working temperature range, has a high energy density, and significantly improves the cycling performance of the aqueous battery.

[0176] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A negative electrode material for an aqueous battery, characterized in that, The negative electrode material of the aqueous battery is micron-sized titanium dioxide; By the electronegativity of the oxygen atoms in the molecules of the micron-sized titanium dioxide attracting the electrons of the hydrogen atoms in the water molecules, and the electronegativity of the oxygen atoms in the water molecules attracting the electrons of the titanium atoms in the micron-sized titanium dioxide, binding sites where water molecules combine with the surface of the micron-sized titanium dioxide are generated on the surface of the micron-sized titanium dioxide, enabling charge transfer between the hydrogen and oxygen atoms of the water molecules and the oxygen and titanium atoms on the surface of the micron-sized titanium dioxide; moreover, under the action of the hydrogen bonds of the water molecules, the water molecules adsorbed on the surface of the micron-sized titanium dioxide form a network structure; Due to the charge transfer and the network structure, when the micron-sized titanium dioxide serves as the negative electrode material of the aqueous battery and contacts the water molecules in the electrolyte, it has higher surface energy and mechanical stability.

2. The negative electrode material for an aqueous battery according to claim 1, wherein The particle size of the micron-sized titanium dioxide is 0.1 μm - 10 μm.

3. The negative electrode material of the aqueous battery according to claim 1, characterized in that The crystal forms of the micron-sized titanium dioxide include: rutile phase (rutile, P42 / mnm), anatase phase (anatase, I41 / amd), brookite phase (brookite, Pbca), TiO2B (bronze, C2 / m), TiO2R (ramsdellite, Pbnm), TiO2H (hollandite, I4 / m), TiO2II (columbite, Pbcn), TiO2III (baddeleyite, P21 / c), one or more of them.

4. The negative electrode of an aqueous battery, characterized in that, The negative electrode of the aqueous battery includes the negative electrode material of the aqueous battery according to any one of claims 1 - 3 above.

5. A water-based battery, characterized in that, The aqueous battery includes: the negative electrode material of the aqueous battery according to any one of claims 1 - 3 above and an aqueous electrolyte.

6. The aqueous battery according to claim 5, wherein The aqueous electrolyte of the aqueous battery is an aqueous solution composed of a metal salt AX that is stable in water; In the metal salt AX, A is a cation, including an alkali metal ion, an alkaline earth metal ion, Zn 2+ or Al 3+ or one or more of them; X is an anion, including NO3 - , SO4 2- , Cl - , Br - , PO4 3- , CO3 2- , CH3COO - , CF3SO3 - , TFSI - , FSI - , BETI - , BF4 - or one or more of them.

7. The aqueous battery according to claim 5, wherein The positive electrode material of the aqueous battery is a lithium-containing positive electrode material.

8. The aqueous battery according to claim 5, wherein The aqueous battery specifically includes: any one of an aqueous rechargeable aluminum battery, an aqueous lithium battery, an aqueous sodium battery, an aqueous potassium battery, an aqueous zinc battery, an aqueous magnesium battery, and an aqueous calcium battery.

Images