An additive for aqueous battery electrolyte and its application

Abstract

This invention discloses an additive for aqueous battery electrolytes and its application. The chemical formula of the additive for aqueous battery electrolytes is TX, specifically a salt or ionic liquid containing a non-hydrated cation; T is a non-hydrated cation, including pyridine cations (C5H5NR). + Quaternary phosphorus cation (R4P) + Triazole cation (C2H2N3R2) + Imidazole cation (C3H3N2R2) + pyrrolidine cation (C4H8NR2) + Piperidine cation (C5H) 10 NR2) + Guanidine cations (CN3R6) + morphazole cation (C4H8ONR2) + 2,2-oxazolidinyl cation (C3H6NOR2) + Amino acid cations (CH3NO2R2) + Sulfonium salt cation (R3S) + X is one or more of the following: other large metal cations with an ionic radius greater than 95 pm; X is an anion, including I... ‑ ,Br ‑ Cl ‑ F ‑ CF3SO3 ‑ (CF3SO2)2N ‑ F2N(SO2)2 ‑ H2PO4 ‑ RCOO ‑ BF4 ‑ One or more of them; during the charging process of an aqueous battery, the non-hydrated cations in the additive TX form a layer of hydrophobic cation molecular sieve on the surface of the battery negative electrode under the action of an electric field, preventing water molecules from undergoing hydrogen evolution on the surface of the battery negative electrode.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy storage devices, and particularly relates to an additive for aqueous battery electrolyte and application thereof. BACKGROUND

[0002] Lithium ion batteries have provided great convenience for the current mobile and intelligent era, but with the continuous expansion of application scenarios and the continuous harshness of application requirements, the safety problems of lithium ion batteries are exposed and increasingly prominent. In recent years, lithium ion battery safety problems have occurred frequently, involving mobile phones, notebook computers, electric vehicles, and spacecraft, etc. It is particularly worth noting that when the energy storage capacity of lithium ion batteries reaches the megawatt level of large-scale energy storage power stations, the damage and loss caused by fire and explosion are immeasurable.

[0003] One of the reasons for the safety accidents of lithium ion batteries is that the organic electrolyte used in the current commercial lithium ion batteries is a flammable substance, which makes the lithium ion battery prone to fire and even explosion when thermal runaway occurs due to accidents. In order to solve this problem, scholars in various countries have begun to study aqueous electrolyte. However, the traditional aqueous electrolyte has a narrow electrochemical window (1.23V), which leads to the low output voltage (less than 2V) of the traditional aqueous battery and the inability to cycle at low rate. In recent years, with the emergence of high-salt aqueous electrolyte (Science. 2015, 350, 6263), the stable window of aqueous solution is widened to more than 3V, thereby greatly improving the output energy density and low-rate cycle performance of aqueous batteries.

[0004] However, high concentration inevitably brings problems such as high viscosity, high cost, low ionic conductivity, poor low-temperature performance, etc. Reducing the concentration of aqueous electrolyte is the trend of the new generation of aqueous energy storage batteries.

[0005] At the same time, high-salt aqueous electrolyte has certain requirements for the solubility of various metal salts, but the solubility of some metal salts (such as sodium, aluminum, etc.) is not high, which leads to a narrow electrochemical window of the electrolyte. At present, the systems (such as lithium, potassium, etc.) that can support high salt solubility are also limited by the solubility of metal salts and cannot further improve the stable electrochemical window of the electrolyte, thereby failing to further improve the energy density of the energy storage device. SUMMARY

[0006] The embodiment of the present application provides an additive of water-based battery electrolyte, which widens the electrochemical window of low-concentration metal salt aqueous solution by containing a salt or ionic liquid TX containing non-hydrated cations, and the principle is as follows: in the charging process of a full battery, the negative electrode is negatively charged, and the non-hydrated large cation can form a hydrophobic cation molecular sieve on the surface of the negative electrode under the action of the electric field, so as to prevent the hydrogen evolution reaction of water molecules at the negative electrode interface, and improve the stability of the water-based electrolyte; meanwhile, the metal salt can break through the original solubility in water and achieve higher solubility.

[0007] In the first aspect, the embodiment of the present application provides an additive of water-based battery electrolyte, which is a salt or ionic liquid TX containing non-hydrated cations, and the chemical formula is TX.

[0008] In the TX, T is a non-hydrated cation, including a pyridine cation (C5H5NR) + , a quaternary phosphonium cation (R4P) + , a triazole cation (C2H2N3R2) + , an imidazole cation (C3H3N2R2) + , a pyrrolidine cation (C4H8NR2) + , a piperidine cation (C5H 10 NR2) + , a guanidine cation (CN3R6) + , a morpholine cation (C4H8ONR2) + , an oxazolidine cation (C3H6NOR2) + , an amino acid cation (CH3NO2R2) + , a sulfonium salt cation (R3S) + or other metal large cations with an ionic radius greater than 95 pm; X is an anion, including one or more of I - , Br - , Cl - , F - , CF3SO3 - , (CF3SO2)2N - , F2N(SO2)2 - , H2PO4 - , RCOO - , BF4 - .

[0009] The electrolyte is an aqueous solution composed of a metal salt AE stable in water; in the metal salt AE, A is a cation, including one or more of an alkali metal ion, an alkaline earth metal ion, Zn 2+ or Al 3+ ; E is an anion, including NO3 - , SO42- , Cl - , Br - , PO4 3- , CO3 2- , CH3COO - , CF3SO3 - , TFSI - , FSI - , BETI - , NFN - , BF4 - , or several of them.

[0010] During the charging process of the aqueous battery, the non-hydrated cations in the additive TX form a layer of hydrophobic cationic molecular sieve on the surface of the negative electrode of the battery under the action of the electric field, preventing the hydrogen evolution of water molecules on the surface of the negative electrode of the battery.

[0011] Preferably, the other metal large cations with an ionic radius greater than 95 pm include: K + , Rb + , or Cs + , or several of them.

[0012] Preferably, the additive TX is applied in the aqueous battery electrolyte, and the concentration of the additive TX ranges from 0.0001 mol / kg to 5 mol / kg, so that the aqueous battery electrolyte has a stable electrochemical window greater than 2V under the condition that the metal salt AE is at a low concentration, wherein the low concentration ranges from 0.0001 mol / kg to 20 mol / kg.

[0013] Preferably, the additive TX is applied in the aqueous battery electrolyte, and the concentration of the additive TX ranges from 0.0001 mol / kg to 100 mol / kg, so that the solubility of the metal salt AE in water is improved, from a low solubility of no more than 20 mol / kg without the additive TX to a high solubility of up to 100 mol / kg with the additive TX.

[0014] Preferably, during the electrochemical reaction of the aqueous battery, the cations in the metal salt AE are inserted into the positive and negative electrode materials of the battery, and the non-hydrated cations in the additive TX are not inserted into the positive and negative electrode materials of the battery. In a second aspect, the present application provides an aqueous battery electrolyte comprising the additive of the aqueous battery electrolyte of the first aspect.

[0015] In a third aspect, the present application provides a battery comprising the additive of the aqueous battery electrolyte of the first aspect, a positive electrode material, and a negative electrode material.

[0016] Preferably, the positive electrode material comprises any one of LiMn2O4, LiFePO4, LiCoO2, LiNi x Co y Mn 1-x-y O2, LiNi x Co y Al 1-x- y Preferably, the negative electrode material comprises any one of anatase TiO2, TiO2(B), Mo6S8, Li4Ti5O 12 , LiTi2(PO4)3; wherein x>0, y>0, x+y<1.

[0017] Preferably, the battery specifically comprises any one of a water-based lithium battery, a water-based sodium battery, a water-based potassium battery, a water-based zinc battery, a water-based magnesium battery, a water-based calcium battery, and a water-based aluminum battery.

[0018] In a fourth aspect, the embodiments of the present application provide a use of the battery as described in the third aspect above, and the battery is applied to a power device of an energy storage power station, a mobile power source of a portable device, an electric vehicle, and a hybrid electric vehicle.

[0019] The additive of the water-based battery electrolyte provided by the embodiments of the present application is used, and the non-hydrated cations of the additive are gathered at the negative electrode interface under the action of an electric field in the charging process of the water-based battery, to form a layer of hydrophobic cation molecular sieve, thereby preventing the hydrogen evolution reaction of water molecules on the negative electrode surface of the battery, and improving the cycle life of the battery.

[0020] The additive of the water-based battery electrolyte provided by the embodiments of the present application is used, and on one hand, the additive can widen the electrochemical window of the water-based battery electrolyte under the condition of maintaining the original low salt concentration, to realize a stable electrochemical window of greater than 2V; on the other hand, the additive can make the metal salt break through the original solubility in water, to achieve a higher solubility, and become a super-high-concentration electrolyte. The high-salt-concentration electrolyte can form an interface confinement at the positive and negative electrode interface, and the water content at the interface is reduced in thermodynamics, and the activity is reduced, and the corrosion of water molecules to the positive and negative electrode materials is reduced; in kinetics, the high viscosity leads to limited diffusion of dissolved substances, and the dissolved substances tend to be enriched on the electrode surface, and the reverse limitation of dissolution is caused; the high-salt-concentration electrolyte is beneficial to the generation of a passivation layer on the surface of the current collector, and can inhibit the corrosion of water to the current collector; thus, the additive of the water-based battery electrolyte provided by the embodiments of the present application can also inhibit the dissolution of the positive and negative electrode materials and reduce the corrosion of the metal current collector.

[0021] The water-based battery electrolyte additive provided by the embodiment of the present application can be used to assemble high-voltage, high-specific energy, long-life and low-cost water-based rechargeable aluminum batteries, alkali metal or alkaline earth metal batteries, such as water-based lithium batteries, water-based sodium batteries, water-based potassium batteries, water-based zinc batteries, water-based aluminum batteries, and the like. The assembled water-based battery can be applied to large-scale energy storage power stations, portable device mobile power sources, electric vehicles, hybrid electric vehicles, and the like. BRIEF DESCRIPTION OF DRAWINGS

[0022] The technical solutions of the embodiments of the present application are described in further detail below with reference to the drawings and examples.

[0023] Figure 1 A mechanism diagram of widening the electrochemical window by the non-hydrated cation in the water-based battery electrolyte additive provided by the embodiment of the present application is shown;

[0024] Figure 2 A solubility phase diagram of LiTFSI under the action of the water-based battery electrolyte additive in the embodiment 1 of the present application is shown;

[0025] Figure 3 A charge-discharge curve of the full battery in the embodiment 1 of the present application at 0.5C rate is shown;

[0026] Figure 4 A cycle performance curve of the full battery in the embodiment 1 of the present application at 0.5C is shown;

[0027] Figure 5 A cycle performance curve of the full battery in the embodiment 1 of the present application at 0.25C is shown;

[0028] Figure 6 A first-week charge-discharge curve of the 8 mAh full battery in the embodiment 2 of the present application is shown;

[0029] Figure 7 A cycle performance curve of the 8 mAh full battery in the embodiment 2 of the present application at 0.5C rate is shown;

[0030] Figure 8 An electrochemical window width diagram of the low-concentration electrolyte in the battery system in the embodiment 3 of the present application is shown;

[0031] Figure 9 A cycle performance comparison diagram of the low-concentration electrolyte with and without the additive in the embodiment 3 of the present application is shown;

[0032] Figure 10 A coulomb efficiency comparison diagram of the low-concentration electrolyte with and without the additive in the embodiment 3 of the present application is shown;

[0033] Figure 11The cycle performance curve of the full battery at 8C in Example 3 of the application is shown;

[0034] Figure 12 The first week charge-discharge curve of the 11 mAh full battery at 0.5C rate in Example 3 of the application is shown;

[0035] Figure 13 The cycle performance curve of the 28 mAh full battery at 0.5C rate in Example 3 of the application is shown;

[0036] Figure 14 The first week charge-discharge curve of the 28 mAh full battery at 0.5C rate in Example 3 of the application is shown;

[0037] Figure 15 The cycle performance curve of the 28 mAh full battery at 0.5C rate in Example 3 of the application is shown;

[0038] Figure 16 The cycle performance comparison curve of the low-concentration electrolyte containing the additive and the high-salt-concentration electrolyte at different temperature conditions in Example 3 of the application is shown;

[0039] Figure 17 The cycle performance comparison curve of the low-concentration electrolyte containing the additive and the high-salt-concentration electrolyte at different rate conditions in Example 3 of the application is shown;

[0040] Figure 18 The cycle performance curve of the full battery of the low-concentration electrolyte containing the additive at 0.5C rate in Example 15 of the application is shown. DETAILED DESCRIPTION

[0041] The application will be further described in detail below in conjunction with examples, but is not intended to limit the protection scope of the application.

[0042] The application provides an additive for aqueous battery electrolyte, with a chemical formula TX, specifically a salt or ionic liquid containing non-hydrated cations;

[0043] In the additive TX, T is a non-hydrated cation, including pyridine cation (C5H5NR) + , quaternary phosphonium cation (R4P) + , triazole cation (C2H2N3R2) + , imidazole cation (C3H3N2R2) + , pyrrolidine cation (C4H8NR2) + , piperidine cation (C5H 10 NR2) + , guanidine cation (CN3R6) +, imidazole cation (C4H8ONR2) + , oxazolidine cation (C3H6NOR2) + , amino acid cation (CH3NO2R2) + , sulfonium cation (R3S) + or one or more of other metal large cations with ionic radius greater than 95 pm; the metal large cations can specifically include: K + , Rb + or Cs + .

[0044] In the additive TX, X is an anion, including one or more of I - , Br - , Cl - , F - , CF3SO3 - , (CF3SO2)2N - , F2N(SO2)2 - , H2PO4 - , RCOO - , BF4 - .

[0045] The aqueous battery electrolyte of the present application is an aqueous solution of a metal salt AE stable in water; in the metal salt AE, A is a cation, including one or more of alkali metal ions, alkaline earth metal ions, Zn 2+ or Al 3+ ; E is an anion, including one or more of NO3 - , SO4 2- , Cl - , Br - , PO4 3- , CO3 2- , CH3COO - , CF3SO3 - , TFSI - , FSI - , BETI - , NFN - , BF4 - .

[0046] In the aqueous battery electrolyte of the present application, the additive TX can have two forms: one is in the form of a salt, or directly dissolved in water, the solubility depends on the difference in ionic size of the anion and cation, or forms a eutectic with lithium salt and water, the solubility depends on the solubility in the eutectic; the other form is an ionic liquid, which is directly miscible with water.

[0047] The application of the additive in the aqueous battery electrolyte of the present application can be divided into the following two kinds:

[0048] The first is to widen the electrochemical window of the aqueous battery electrolyte while maintaining the original low salt concentration. Specifically, the additive TX is applied in the aqueous battery electrolyte, and the concentration of the additive TX is in the range of 0.0001 mol / kg-5 mol / kg, so that the aqueous battery electrolyte has a stable electrochemical window of more than 2V under the condition that the metal salt AE is in a low concentration, and the low concentration is in the range of 0.0001 mol / kg-20 mol / kg.

[0049] The second is to make the metal salt break through its original solubility in water to achieve a higher solubility, becoming a super-high concentration electrolyte. Specifically, the additive TX is applied in the aqueous battery electrolyte, and the concentration of the additive TX is in the range of 0.0001 mol / kg-100 mol / kg, so that the solubility of the metal salt AE in water is improved, from the low solubility without adding the additive TX to the high solubility after adding the additive TX; wherein the low solubility is not more than 20 mol / kg, and the high solubility can reach 100 mol / kg.

[0050] In the electrochemical reaction process of the aqueous battery, the cations in the metal salt AE are inserted into the positive and negative electrode materials of the battery, and the non-hydrated cations in the additive TX are not inserted into the positive and negative electrode materials of the battery.

[0051] Figure 1 The mechanism diagram of the non-hydrated cations in the additive of the aqueous battery electrolyte widening the electrochemical window. It can be seen that during the charging process of the full battery, the negative electrode is negatively charged, and the non-hydrated large cations can form a layer of hydrophobic cation molecular sieve on the surface of the negative electrode under the action of the electric field, thereby preventing the hydrogen evolution reaction of water molecules at the negative electrode interface and improving the stability of the aqueous electrolyte. Since the reaction of water molecules at the negative electrode interface can be reduced, high salt concentration is no longer a necessary condition for the aqueous electrolyte, and low concentration electrolyte can achieve the same stability as high concentration electrolyte, thereby reducing the concentration of the aqueous electrolyte and further reducing the cost of the aqueous electrolyte.

[0052] By applying the additive of the present application to the aqueous battery electrolyte of the embodiment of the present application, on the one hand, the electrochemical window of the aqueous battery electrolyte can be widened while maintaining the original low salt concentration, achieving a stable electrochemical window of more than 2V; on the other hand, the metal salt can break through its original solubility in water to achieve a higher solubility, becoming a super-high concentration electrolyte, which can inhibit the dissolution of the positive and negative electrode materials and reduce the corrosion of the metal current collector. In addition, in the charging process of the aqueous battery, the non-hydrated cations in the additive form a layer of hydrophobic cation molecular sieve on the surface of the negative electrode of the battery under the action of the electric field, preventing the hydrogen evolution of water molecules on the surface of the negative electrode of the battery.

[0053] The additives for the aqueous battery electrolyte provided in this invention can be used to assemble high-voltage, high-energy-density, long-life, and low-cost aqueous batteries. The positive electrode materials include LiMn2O4, LiFePO4, LiCoO2, and LiNi. x Co y Mn 1-x-y O2, LiNi x Co y Al 1-x-y Any of the following O2; the negative electrode material includes anataseTiO2, TiO2(B), Mo6S8, Li4Ti5O 12 It can be any one of LiTi2(PO4)3; where x>0, y>0, and x+y<1.

[0054] Aqueous batteries can specifically include aqueous rechargeable aluminum batteries, alkali metal or alkaline earth metal batteries, such as aqueous lithium batteries, aqueous sodium batteries, aqueous potassium batteries, aqueous zinc batteries, aqueous magnesium batteries, and aqueous calcium batteries. Assembled aqueous batteries can be applied in large-scale energy storage power stations, portable power sources for mobile devices, electric vehicles, and hybrid electric vehicles.

[0055] Example 1

[0056] This embodiment uses EMIMTFSI(C8H) 11 F6N3O4S2 (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt) is used as an additive.

[0057] The solubility of LiTFSI in pure water is 21 mol / kg.

[0058] With only 1 mol / kg of additive, the solubility of LiTFSI can reach 26 mol / kg;

[0059] With the addition of 3 mol / kg additive, the solubility of LiTFSI can reach 30 mol / kg, forming an ultra-high salt electrolyte of 30 mol / kg LiTFSI + 3 mol / kg EMIMTFSI (denoted as electrolyte 1);

[0060] With the addition of 5 mol / kg additive, the solubility of LiTFSI can reach 32 mol / kg;

[0061] With the addition of 7 mol / kg additive, the solubility of LiTFSI can reach 41 mol / kg;

[0062] With the addition of 9 mol / kg additive, the solubility of LiTFSI can reach 42 mol / kg;

[0063] The solubility of LiTFSI can reach 43 mol / kg under the action of 11 mol / kg additive;

[0064] The above data are recorded in Table 1 and shown in Figure 2 The above data are recorded in Table 1 and shown in

[0065]

[0066] Table 1

[0067] Two groups of batteries were assembled with LiMn2O4 as the positive electrode material, untreated anatase TiO2 as the negative electrode material, and electrolyte 1 as the electrolyte, wherein the positive electrode current collector was an anti-corrosion treated titanium mesh and an aluminum mesh, respectively, and the negative electrode current collector was an aluminum mesh.

[0068] Figure 3 The cycle performance of LiMn2O4 / 30 mol / kg LiTFSI+3 mol / kg EMIMTFSI / TiO2 full battery (the positive electrode current collector was an anti-corrosion treated titanium mesh, and the negative electrode current collector was an aluminum mesh) at a 0.5C rate was shown, the first week discharge specific capacity was 134.65 mAh / g (calculated based on the mass of the active material of the negative electrode), the first week charge-discharge efficiency was 85.68%, and the cycle capacity retention rate after 150 weeks was 83.35%. The specific results are recorded in Table 2.

[0069] Figure 4 The cycle performance of LiMn2O4 / 30 mol / kg LiTFSI+3 mol / kg EMIMTFSI / TiO2 full battery (the positive electrode current collector was an anti-corrosion treated titanium mesh, and the negative electrode current collector was an aluminum mesh) at a 0.5C rate was shown, the first week discharge specific capacity was 134.65 mAh / g (calculated based on the mass of the active material of the negative electrode), the first week charge-discharge efficiency was 85.68%, and the cycle capacity retention rate after 150 weeks was 83.35%. The specific results are recorded in Table 2.

[0070] Example 2

[0071] Electrolyte 2 used: 18 mol / kg LiTFSI+3 mol / kg EMIMTFSI.

[0072] Two groups of batteries were assembled with LiMn2O4 as the positive electrode material, untreated anatase TiO2 as the negative electrode material, and electrolyte 2 as the electrolyte, wherein the positive electrode current collector was an anti-corrosion treated titanium mesh and an anti-corrosion untreated titanium mesh, respectively, and the negative electrode current collector was an aluminum mesh.

[0073] Figure 5The cycle performance of LiMn2O4 / 18 mol / kg LiTFSI + 3 mol / kg EMIMTFSI / TiO2 full cell (positive electrode current collector is anti-corrosion treated titanium mesh, negative electrode current collector is aluminum mesh) at 0.25C rate is shown, the first week discharge specific capacity is 151.60 mAh / g (calculated based on the mass of active substances of the negative electrode), the first week charge-discharge efficiency is 84%, and the capacity retention rate after 100 weeks of cycling is 82.76%. The specific results are recorded in Table 2.

[0074] Figure 6 The first week charge-discharge curve of LiMn2O4 / 18 mol / kg LiTFSI + 3 mol / kg EMIMTFSI / TiO2 full cell (positive electrode current collector is anti-corrosion treated titanium mesh, negative electrode current collector is aluminum mesh) at 0.5C rate is shown, the first week discharge capacity is 8.688 mAh, the first week discharge specific capacity is 52.96 mAh / g (calculated based on the mass of active substances of the positive and negative electrodes), the first week charge-discharge efficiency is 90.83%, and the output energy density is 111.38 Wh / kg (calculated based on the mass of active substances of the positive and negative electrodes). The specific results are recorded in Table 2.

[0075] Figure 7 The cycle performance of 8.688 mAh level LiMn2O4 / 18 mol / kg LiTFSI + 3 mol / kg EMIMTFSI / TiO2 full cell (positive electrode current collector is anti-corrosion treated titanium mesh, negative electrode current collector is aluminum mesh) at 0.5C rate is shown, the capacity decay rate is 0.21% per week after 190 weeks of cycling. The specific results are recorded in Table 2.

[0076] Example 3

[0077] This example provides electrolyte 3, the concentration of LiTFSI is set to 13.8 mol / kg, so that all water molecules in the electrolyte just produce solvation with Li ions, and 1 mol / kg EMIMTFSI is added to play a role in widening the window.

[0078] Figure 8 The electrochemical window of the low-concentration electrolyte 13.8 mol / kg LiTFSI + 1 mol / kg EMIMTFSI (electrolyte 3) containing an additive and the 13.8 mol / kg LiTFSI electrolyte without an additive on the negative electrode side is shown. It can be seen that the electrochemical window of the low-concentration electrolyte containing an additive is wider than that of the low-concentration electrolyte 13.8 mol / kg LiTFSI without an additive.

[0079] Multiple battery packs were assembled using LiMn2O4 as the positive electrode material, carbon-coated anatase TiO2 (C-TiO2) as the negative electrode material, electrolyte 3 and a 13.8 mol / kg LiTFSI electrolyte without additives for comparison with electrolyte 3. The positive electrode current collector was a titanium mesh with anti-corrosion treatment or a titanium mesh with anti-corrosion treatment + aluminum foil, and the negative electrode current collector was an aluminum mesh or aluminum foil.

[0080] Figure 9 The cycling performance of LiMn2O4 / 13.8 mol / kg LiTFSI + 1 mol / kg EMIMTFSI / C-TiO2 full cells and LiMn2O4 / 13.8 mol / kg LiTFSI / C-TiO2 full cells (both with corrosion-resistant titanium mesh as the positive electrode current collector and aluminum mesh as the negative electrode current collector) at 0.5C rate was demonstrated. The results are recorded in Table 2. The results show that the additives of this invention can improve the cycling stability of the full cells. Specific results are recorded in Table 2.

[0081] Figure 10 The cycling performance of LiMn2O4 / 13.8mol / kgLiTFSI+1mol / kgEMIMTFSI / C-TiO2 full cells and LiMn2O4 / 13.8mol / kgLiTFSI / C-TiO2 full cells (both positive electrode current collectors are corrosion-resistant titanium mesh, and both negative electrode current collectors are aluminum mesh) at a rate of 0.5C was demonstrated. As shown in the figure, the application of the additives of the present invention can improve the coulombic efficiency of the full cells.

[0082] Figure 11 The charge-discharge curves of a LiMn2O4 / 13.8mol / kg LiTFSI+1mol / kg EMIMTFSI / C-TiO2 full cell (with corrosion-resistant titanium mesh and aluminum foil as the positive electrode current collector and aluminum mesh as the negative electrode current collector) at an 8C rate are shown. The first-cycle discharge capacity is 35.45 mAh / g (calculated based on the mass of the positive and negative electrode active materials), and the capacity retention rate is 70% after 1000 cycles. Detailed results are recorded in Table 2.

[0083] Figure 12The first-week charge-discharge curves of a LiMn2O4 / 13.8 mol / kg LiTFSI+1 mol / kg EMIMTFSI / C-TiO2 full cell (positive electrode current collector: anti-corrosion titanium mesh and aluminum foil; negative electrode current collector: aluminum foil) at 3C rate are shown. The first-week discharge capacity is 11.139 mAh, the first-week discharge specific capacity is 41.97 mAh / g (calculated based on the mass of the active materials at both positive and negative electrodes), the first-week charge-discharge efficiency is 82.60%, and the output energy density is 84.18 Wh / kg (calculated based on the mass of the active materials at both positive and negative electrodes). Detailed results are recorded in Table 2.

[0084] Figure 13 The cycling performance of an 11.139mAh-class LiMn2O4 / 13.8mol / kg LiTFSI+1mol / kg EMIMTFSI / C-TiO2 full cell (with corrosion-resistant titanium mesh and aluminum foil as the positive electrode current collector and aluminum foil as the negative electrode current collector) at 3C rate was demonstrated, with a capacity retention of 71% after 350 cycles. Specific results are recorded in Table 2.

[0085] Figure 14 The first-week charge-discharge curves of a LiMn2O4 / 13.8mol / kg LiTFSI+1mol / kg EMIMTFSI / C-TiO2 full cell (with corrosion-resistant titanium mesh and aluminum foil as the positive electrode current collector and aluminum foil as the negative electrode current collector) at 0.5% rate are shown. The first-week discharge capacity is 27.60mAh, the first-week discharge specific capacity is 38.63mAh / g (calculated based on the mass of the active materials at both positive and negative electrodes), the first-week charge-discharge efficiency is 74.96%, and the output energy density is 77.79Wh / kg (calculated based on the mass of the active materials at both positive and negative electrodes). Detailed results are recorded in Table 2.

[0086] Figure 15 The cycling performance of an 11.139 mAh LiMn2O4 / 13.8 mol / kg LiTFSI+1 mol / kg EMIMTFSI / C-TiO2 full cell (with corrosion-resistant titanium mesh and aluminum foil as the positive electrode current collector and aluminum foil as the negative electrode current collector) at 0.5C rate was demonstrated, with a capacity retention of 78% after 200 cycles. Specific results are recorded in Table 2.

[0087] Figure 16The cycling performance of two full cells—LiMn₂O₄ / 13.8 mol / kg LiTFSI + 1 mol / kg EMIMTFSI / C-TiO₂ and LiMn₂O₄ / 21 mol / kg LiTFSI + 7 mol / kg LiOTF / C-TiO₂ (both with corrosion-resistant titanium mesh as the positive electrode current collector and aluminum mesh as the negative electrode current collector)—at different temperatures is shown in Table 3. The results indicate that the low-temperature performance of the full cell is better as the electrolyte concentration decreases.

[0088] Figure 17 The cycling performance of two full cells—LiMn2O4 / 13.8 mol / kg LiTFSI + 1 mol / kg EMIMTFSI / C-TiO2 and LiMn2O4 / 21 mol / kg LiTFSI + 7 mol / kg LiOTF / C-TiO2 (both with corrosion-resistant titanium mesh as the positive electrode current collector and aluminum mesh as the negative electrode current collector)—at different temperatures is shown in Table 4. It can be seen that the rate performance of the full cell is better when the electrolyte concentration decreases.

[0089]

[0090] Table 2

[0091]

[0092] Table 3

[0093]

[0094] Table 4

[0095] Example 4

[0096] The aqueous battery electrolyte additive proposed in this embodiment is BMPTFSI(C) 11 H 20 F6N2O4S2 (N-methyl, butylpyrrolidine bis(trifluoromethanesulfonyl)imide salt) can enable metal salts to break through the solubility in water and achieve higher solubility, forming ultra-high saline electrolyte.

[0097] The solubility of LiTFSI in pure water is 21 mol / kg.

[0098] With only 1 mol / kg of additive, the solubility of LiTFSI can reach 25 mol / kg;

[0099] With the addition of 3 mol / kg additive, the solubility of LiTFSI can reach 28 mol / kg;

[0100] With the addition of 5 mol / kg additive, the solubility of LiTFSI can reach 30 mol / kg to form an ultra-high salt electrolyte: 30 mol / kg LiTFSI + 5 mol / kg BMPTFSI (electrolyte 4);

[0101] With the addition of 7 mol / kg additive, the solubility of LiTFSI can reach 37 mol / kg;

[0102] With the addition of 9 mol / kg additive, the solubility of LiTFSI can reach 38 mol / kg;

[0103] With the addition of 11 mol / kg additive, the solubility of LiTFSI can reach 39 mol / kg.

[0104] Table 5 lists the additives BMPTFSI (C) 11 H 20 The solubilization effect of F6N2O4S2 (N-methyl, butylpyrrolidine bis(trifluoromethanesulfonyl)imide salt) on LiTFSI.

[0105]

[0106] Table 5

[0107] Two sets of batteries were assembled using LiMn2O4 as the positive electrode material, untreated anatase TiO2 as the negative electrode material, and electrolyte 4 as the electrolyte. The positive electrode current collectors were titanium mesh and aluminum mesh that had undergone anti-corrosion treatment, respectively, and the negative electrode current collector was aluminum mesh.

[0108] The cycling performance of a LiMn2O4 / 30mol / kg LiTFSI+5mol / kg BMPTFSI / TiO2 full cell (with a corrosion-resistant titanium mesh as the positive electrode current collector and an aluminum mesh as the negative electrode current collector) at a 0.5C rate is as follows: the discharge specific capacity in the first week is 133.72mAh / g (calculated based on the mass of the active material at the negative electrode), the charge-discharge efficiency in the first week is 83.57%, and the capacity retention rate after 150 cycles is 81.32%. The results are shown in Table 6.

[0109] The cycling performance of the LiMn2O4 / 30mol / kg LiTFSI+5mol / kg BMPTFSI / TiO2 full cell (with aluminum mesh as the current collector for both positive and negative electrodes) at a 0.5C rate is as follows: the discharge specific capacity in the first week is 123.76mAh / g (calculated based on the mass of the active material at the negative electrode), the charge-discharge efficiency in the first week is 77.56%, and the capacity retention rate after 130 cycles is 75.48%. The results are shown in Table 6.

[0110] Example 5

[0111] The electrolyte additive proposed in this embodiment is BMPTFSI, which is prepared as a low-concentration aqueous electrolyte (electrolyte 5) of 18 mol / kg LiTFSI + 3 mol / kg BMPTFSI. Two sets of batteries are assembled with LiMn2O4 as the positive electrode material, untreated anatase TiO2 as the negative electrode material, and electrolyte 5 as the electrolyte. The positive electrode current collectors are titanium mesh with anti-corrosion treatment and untreated titanium mesh, respectively, and the negative electrode current collector is aluminum mesh.

[0112] The cycling performance of a LiMn2O4 / 18mol / kg LiTFSI+3mol / kg BMPTFSI / TiO2 full cell (with a corrosion-resistant titanium mesh as the positive electrode current collector and an aluminum mesh as the negative electrode current collector) at a rate of 0.25C is as follows: the discharge specific capacity in the first week is 148.42mAh / g (calculated based on the mass of the active material at the negative electrode), the charge-discharge efficiency in the first week is 82.73%, and the capacity retention rate after 100 cycles is 81.36%. The results are shown in Table 6.

[0113] The LiMn2O4 / 18mol / kg LiTFSI+3mol / kg BMPTFSI / TiO2 full cell (with titanium mesh as the positive electrode current collector and aluminum mesh as the negative electrode current collector) exhibited the following first-cycle discharge capacity at 0.5C: 7.422mAh, 51.72mAh / g (based on the mass of the active materials at both positive and negative electrodes), 89.76% charge-discharge efficiency, and 110.63Wh / kg output energy density (based on the mass of the active materials at both positive and negative electrodes). After 180 cycles, the capacity retention was 68.59%, as shown in Table 6.

[0114] Example 6

[0115] This embodiment provides electrolyte 6, with the concentration of LiTFSI set to 13.8 mol / kg, so that all water molecules in the electrolyte are just enough to solvate with Li ions. Then, 3 mol / kg BMPTFSI is added to broaden the solvation window.

[0116] The positive electrode material of the battery is LiMn2O4, the negative electrode material is untreated anatase TiO2, the electrolyte is electrolyte 6, the positive electrode current collector is titanium mesh, and the negative electrode current collector is aluminum mesh.

[0117] The LiMn2O4 / 13.8mol / kg LiTFSI+3mol / kg BMPTFSI / TiO2 full cell (positive electrode current collector is an untreated titanium mesh, negative electrode current collector is an aluminum mesh) had an initial discharge capacity of 5.633mAh at 0.5C rate, an initial discharge specific capacity of 50.93mAh / g (based on the mass of the active materials of the positive and negative electrodes), an initial charge-discharge efficiency of 83.93%, an output energy density of 107.73Wh / kg (based on the mass of the active materials of the positive and negative electrodes), and a capacity retention of 70.72% after 150 cycles. The results are shown in Table 6.

[0118]

[0119] Table 6

[0120] Example 7

[0121] The aqueous battery electrolyte additive proposed in this embodiment is [Hpy]NTF2(C 13 H 18 O4N2S2F6 (N-hexylpyridine bis(trifluoromethanesulfonyl)imide salt), this aqueous battery electrolyte additive can enable metal salts to break through the solubility in water and achieve higher solubility, forming an ultra-high saline electrolyte.

[0122] The solubility of LiTFSI in pure water is 21 mol / kg.

[0123] With only 1 mol / kg of additive, the solubility of LiTFSI can reach 24 mol / kg;

[0124] With the addition of 3 mol / kg additive, the solubility of LiTFSI can reach 27 mol / kg;

[0125] With the addition of 5 mol / kg additive, the solubility of LiTFSI can reach 29 mol / kg;

[0126] With the addition of 7 mol / kg additive, the solubility of LiTFSI can reach 33 mol / kg to form an ultra-high salt electrolyte: 33 mol / kg LiTFSI + 7 mol / kg [Hpy]NTF2 (electrolyte 7);

[0127] With the addition of 9 mol / kg additive, the solubility of LiTFSI can reach 34 mol / kg;

[0128] With the addition of 11 mol / kg additive, the solubility of LiTFSI can reach 35 mol / kg.

[0129] Table 7 lists the additive [Hpy]NTF2(C 13 H18 The solubilization effect of O4N2S2F6, N-hexylpyridine bis(trifluoromethanesulfonyl)imide salt on LiTFSI.

[0130]

[0131] Table 7

[0132] Two sets of batteries were assembled using LiMn2O4 as the positive electrode material, untreated anatase TiO2 as the negative electrode material, and electrolyte 7 as the electrolyte. The positive electrode current collectors were titanium mesh and aluminum mesh that had undergone anti-corrosion treatment, respectively, and the negative electrode current collector was aluminum mesh.

[0133] The cycling performance of a LiMn2O4 / 33mol / kg LiTFSI+7mol / kg[Hpy]NTF2 / TiO2 full cell (positive electrode current collector is a corrosion-resistant titanium mesh, negative electrode current collector is an aluminum mesh) at 0.5C rate is as follows: the discharge specific capacity in the first week is 130.69mAh / g (calculated based on the mass of the active material of the negative electrode), the charge-discharge efficiency in the first week is 82.86%, and the capacity retention rate after 150 cycles is 80.92%. The results are shown in Table 8.

[0134] The cycling performance of the LiMn2O4 / 33mol / kgLiTFSI+7mol / kg[Hpy]NTF2 / TiO2 full cell (with aluminum mesh as the current collector for both positive and negative electrodes) at a 0.5C rate is as follows: the discharge specific capacity in the first week is 122.56mAh / g (calculated based on the mass of the active material at the negative electrode), the charge-discharge efficiency in the first week is 76.87%, and the capacity retention rate after 130 cycles is 79.48%. The results are shown in Table 8.

[0135] Example 8

[0136] The electrolyte additive proposed in this embodiment is BMPTFSI, which is formulated into a low-concentration aqueous electrolyte (electrolyte 8) of 18 mol / kg LiTFSI + 3 mol / kg [Hpy]NTF2. Two sets of batteries are assembled with LiMn2O4 as the positive electrode material, untreated anatase TiO2 as the negative electrode material, and electrolyte 8 as the electrolyte. The positive electrode current collectors are titanium mesh with anti-corrosion treatment and untreated titanium mesh, respectively, and the negative electrode current collector is aluminum mesh.

[0137] The cycling performance of a LiMn2O4 / 18mol / kg LiTFSI+3mol / kg[Hpy]NTF2 / TiO2 full cell (positive electrode current collector is a corrosion-resistant titanium mesh, negative electrode current collector is an aluminum mesh) at a rate of 0.25C is as follows: the discharge specific capacity in the first week is 147.98mAh / g (calculated based on the mass of the active material of the negative electrode), the charge-discharge efficiency in the first week is 84.73%, and the capacity retention rate after 100 cycles is 80.98%. The results are shown in Table 8.

[0138] The LiMn2O4 / 18mol / kg LiTFSI+3mol / kg[Hpy]NTF2 / TiO2 full cell (positive electrode current collector is untreated titanium mesh, negative electrode current collector is aluminum mesh) had an initial discharge capacity of 7.897mAh at 0.5C rate, an initial discharge specific capacity of 50.98mAh / g (based on the mass of active materials at the positive and negative electrodes), an initial charge-discharge efficiency of 88.75%, and an output energy density of 109.72Wh / kg (based on the mass of active materials at the positive and negative electrodes). After 180 cycles, the capacity retention rate was 69.57%, as shown in Table 8.

[0139] Example 9

[0140] In this embodiment, electrolyte 9 is provided, and the concentration of LiTFSI is set to 13.8 mol / kg so that all water molecules in the electrolyte are just enough to solvate with Li ions. Then, 3 mol / kg of [Hpy]NTF2 is added to widen the solvation window.

[0141] The positive electrode material of the battery is LiMn2O4, the negative electrode material is untreated anatase TiO2, the electrolyte is electrolyte 9, the positive electrode current collector is a titanium mesh without anti-corrosion treatment, and the negative electrode current collector is an aluminum mesh.

[0142] The LiMn2O4 / 13.8mol / kg LiTFSI+3mol / kg[Hpy]NTF2 / TiO2 full cell (with titanium mesh as the positive electrode current collector and aluminum mesh as the negative electrode current collector) had a first-cycle discharge capacity of 6.033mAh and a first-cycle discharge specific capacity of 50.05mAh / g (based on the mass of the active materials at the positive and negative electrodes). The first-cycle charge-discharge efficiency was 85.64%, and the output energy density was 108.73Wh / kg (based on the mass of the active materials at the positive and negative electrodes). The capacity retention rate after 150 cycles was 47.54%. The results are shown in Table 8.

[0143]

[0144] Table 8

[0145] Example 10

[0146] The aqueous battery electrolyte additive proposed in this embodiment is EMMPNTF2(C9H 16 N2O5H3F6S2 (N-methyl, ethylmorpholine bis(trifluoromethanesulfonyl)imide salt), this aqueous battery electrolyte additive can enable metal salts to break through the solubility in water and achieve higher solubility, forming an ultra-high saline electrolyte.

[0147] The solubility of LiTFSI in pure water is 21 mol / kg.

[0148] With only 1 mol / kg of additive, the solubility of LiTFSI can reach 22 mol / kg;

[0149] With the addition of 3 mol / kg additive, the solubility of LiTFSI can reach 24 mol / kg;

[0150] With the addition of 5 mol / kg additive, the solubility of LiTFSI can reach 26 mol / kg;

[0151] With the addition of 7 mol / kg additive, the solubility of LiTFSI can reach 30 mol / kg to form an ultra-high salt electrolyte: 30 mol / kg LiTFSI + 7 mol / kg EMMNTF2 (electrolyte 10);

[0152] With the addition of 9 mol / kg additive, the solubility of LiTFSI can reach 31 mol / kg;

[0153] With the addition of 11 mol / kg additive, the solubility of LiTFSI can reach 32 mol / kg.

[0154] Table 9 lists the additive EMMPNTF2 (C9H) 16 The solubilization effect of N2O5H3F6S2 (N-methyl, ethylmorpholine bis(trifluoromethanesulfonyl)imide salt) on LiTFSI.

[0155]

[0156] Table 9

[0157] Two sets of batteries were assembled using LiMn2O4 as the positive electrode material, untreated anatase TiO2 as the negative electrode material, and electrolyte 10 as the electrolyte. The positive electrode current collectors were titanium mesh and aluminum mesh that had undergone anti-corrosion treatment, respectively, and the negative electrode current collector was aluminum mesh.

[0158] The cycling performance of the LiMn2O4 / 30mol / kgLiTFSI+7mol / kgEMMPNTF2 / TiO2 full cell (the positive electrode current collector is a corrosion-resistant titanium mesh, and the negative electrode current collector is an aluminum mesh) at a 0.5C rate is as follows: the discharge specific capacity in the first week is 129.63mAh / g (calculated based on the mass of the active material of the negative electrode), the charge-discharge efficiency in the first week is 86.34%, and the capacity retention rate after 150 cycles is 80.06%. The results are shown in Table 10.

[0159] The cycling performance of the LiMn2O4 / 30mol / kg LiTFSI+7mol / kg EMMPNTF2 / TiO2 full cell (with aluminum mesh as the current collector for both positive and negative electrodes) at a 0.5C rate is as follows: the discharge specific capacity in the first week is 120.87mAh / g (calculated based on the mass of the active material at the negative electrode), the charge-discharge efficiency in the first week is 78.36%, and the capacity retention rate after 130 cycles is 76.23%. The results are shown in Table 10.

[0160] Example 11

[0161] The electrolyte additive proposed in this embodiment is EMMPNTF2, which is used to prepare a low-concentration aqueous electrolyte (electrolyte 11) of 18 mol / kg LiTFSI + 3 mol / kg EMMPNTF2. The use of additive EMMPNTF2 can reduce the overall concentration of the electrolyte.

[0162] Two sets of batteries were assembled using LiMn2O4 as the positive electrode material, untreated anatase TiO2 as the negative electrode material, and electrolyte 11 as the electrolyte. The positive electrode current collectors were titanium mesh with anti-corrosion treatment and untreated titanium mesh, respectively, and the negative electrode current collector was aluminum mesh.

[0163] The cycling performance of a LiMn2O4 / 18mol / kg LiTFSI+3mol / kg EMMPNTF2 / TiO2 full cell (with a corrosion-resistant titanium mesh as the positive electrode current collector and an aluminum mesh as the negative electrode current collector) at a rate of 0.25C is as follows: the discharge specific capacity in the first week is 140.74mAh / g (calculated based on the mass of the active material at the negative electrode), the charge-discharge efficiency in the first week is 83.92%, and the capacity retention rate after 100 cycles is 77.56%. The results are shown in Table 10.

[0164] The LiMn2O4 / 18mol / kg LiTFSI+3mol / kg EMMPNTF2 / TiO2 full cell (positive electrode current collector is an untreated titanium mesh, negative electrode current collector is an aluminum mesh) showed the following discharge capacity at 0.5C rate: first-cycle discharge capacity of 8.052mAh, first-cycle discharge specific capacity of 50.42mAh / g (based on the mass of active materials at the positive and negative electrodes), first-cycle charge-discharge efficiency of 84.74%, output energy density of 105.63Wh / kg (based on the mass of active materials at the positive and negative electrodes), and capacity retention of 72.68% after 180 cycles. The results are shown in Table 10.

[0165] Example 12

[0166] In this embodiment, electrolyte 12 is provided, and the concentration of LiTFSI is set to 13.8 mol / kg so that all water molecules in the electrolyte are just enough to solvate with Li ions. Then, 3 mol / kg EMMPNTF2 is added to widen the solvation window.

[0167] The positive electrode material of the battery is LiMn2O4, the negative electrode material is untreated anatase TiO2, the electrolyte is electrolyte 12, the positive electrode current collector is a titanium mesh without anti-corrosion treatment, and the negative electrode current collector is an aluminum mesh.

[0168] The LiMn2O4 / 13.8mol / kg LiTFSI+3mol / kg EMMPNTF2 / TiO2 full cell (with titanium mesh as the positive electrode current collector and aluminum mesh as the negative electrode current collector) exhibited the following first-cycle discharge capacity at 0.5C: 6.875mAh, 49.93mAh / g (based on the mass of the active materials at both positive and negative electrodes), 80.43% charge-discharge efficiency, and 105.73Wh / kg output energy density (based on the mass of the active materials at both positive and negative electrodes). After 150 cycles, the capacity retention was 75.87%, as shown in Table 10.

[0169]

[0170] Table 10

[0171] Example 13

[0172] The aqueous battery electrolyte additive proposed in this embodiment is CsTFSI (CsC2F6NO4S2, bis(trifluoromethylsulfonyl)imide cesium). This aqueous battery electrolyte additive can enable metal salts to break through the solubility in water and achieve higher solubility, forming an ultra-high saline electrolyte.

[0173] The solubility of LiTFSI in pure water is 21 mol / kg.

[0174] With only 1 mol / kg of additive, the solubility of LiTFSI can reach 23 mol / kg;

[0175] With the addition of 3 mol / kg additive, the solubility of LiTFSI can reach 29 mol / kg;

[0176] With the addition of 5 mol / kg additive, the solubility of LiTFSI can reach 32 mol / kg;

[0177] With the addition of 7 mol / kg additive, the solubility of LiTFSI can reach 34 mol / kg to form an ultra-high salt electrolyte: 34 mol / kg LiTFSI + 7 mol / kg SAHCl (electrolyte 13);

[0178] With the addition of 9 mol / kg additive, the solubility of LiTFSI can reach 36 mol / kg;

[0179] With the addition of 11 mol / kg additive, the solubility of LiTFSI can reach 37 mol / kg.

[0180] Table 11 shows the solubilization results of the additive CsTFSI (CsC2F6NO4S2, bis(trifluoromethylsulfonyl)imide cesium) on LiTFSI.

[0181]

[0182] Table 11

[0183] Two sets of batteries were assembled using LiMn2O4 as the positive electrode material, untreated anatase TiO2 as the negative electrode material, and electrolyte 13 as the electrolyte. The positive electrode current collectors were titanium mesh and aluminum mesh that had undergone anti-corrosion treatment, respectively, and the negative electrode current collector was aluminum mesh.

[0184] The cycling performance of a LiMn2O4 / 34mol / kg LiTFSI+7mol / kg CsTFSI / TiO2 full cell (with a corrosion-resistant titanium mesh as the positive electrode current collector and an aluminum mesh as the negative electrode current collector) at a 0.5C rate is as follows: the discharge specific capacity in the first week is 130.62mAh / g (calculated based on the mass of the active material at the negative electrode), the charge-discharge efficiency in the first week is 81.36%, and the capacity retention rate after 150 cycles is 82.36%. The results are shown in Table 12.

[0185] The cycling performance of the LiMn2O4 / 34mol / kg LiTFSI+7mol / kg CsTFSI / TiO2 full cell (with aluminum mesh as the current collector for both positive and negative electrodes) at a 0.5C rate is as follows: the discharge specific capacity in the first week is 132.73mAh / g (calculated based on the mass of the active material at the negative electrode), the charge-discharge efficiency in the first week is 75.42%, and the capacity retention rate after 150 cycles is 77.86%. The results are shown in Table 12.

[0186] Example 14

[0187] The electrolyte additive proposed in this embodiment is CsTFSI, which is used to prepare a low-concentration aqueous electrolyte (electrolyte 14) of 18 mol / kg LiTFSI + 3 mol / kg CsTFSI.

[0188] Two sets of batteries were assembled using LiMn2O4 as the positive electrode material, untreated anatase TiO2 as the negative electrode material, and electrolyte 14 as the electrolyte. The positive electrode current collectors were titanium mesh with anti-corrosion treatment and untreated titanium mesh, respectively, and the negative electrode current collector was aluminum mesh.

[0189] The cycling performance of a LiMn2O4 / 18mol / kg LiTFSI+3mol / kg CsTFSI / TiO2 full cell (with a corrosion-resistant titanium mesh as the positive electrode current collector and an aluminum mesh as the negative electrode current collector) at a rate of 0.25C is as follows: the discharge specific capacity in the first week is 147.86mAh / g (calculated based on the mass of the active material at the negative electrode), the charge-discharge efficiency in the first week is 80.86%, and the capacity retention rate after 100 cycles is 82.56%. The results are shown in Table 12.

[0190] The LiMn2O4 / 18mol / kg LiTFSI+3mol / kg CsTFSI / TiO2 full cell (with titanium mesh as the positive electrode current collector and aluminum mesh as the negative electrode current collector) exhibited the following first-cycle discharge capacity at 0.5C: 14.786 mAh, 43.85 mAh / g (calculated based on the mass of the active materials at both positive and negative electrodes), 81.39% charge-discharge efficiency, and 90.39 Wh / kg output energy density (calculated based on the mass of the active materials at both positive and negative electrodes). After 200 cycles, the capacity retention was 78.68%, as shown in Table 12.

[0191] Example 15

[0192] In this embodiment, electrolyte 15 is provided, and the concentration of LiTFSI is set to 13.8 mol / kg, so that all water molecules in the electrolyte are just enough to solvate with Li ions. Then, 1 mol / kg CsTFSI is added to broaden the solvation window.

[0193] The positive electrode material of the battery is LiMn2O4, the negative electrode material is C-TiO2, the electrolyte is Electrolyte 15, the positive electrode current collector is corrosion-resistant titanium mesh and aluminum foil, and the negative electrode current collector is aluminum foil.

[0194] Figure 18 The results show that the LiMn2O4 / 13.8mol / kg LiTFSI+1mol / kg CsTFSI / C-TiO2 full cell (positive electrode current collector is corrosion-resistant titanium mesh and aluminum foil, negative electrode current collector is aluminum mesh) has a discharge specific capacity of 47.43 mAh / g (based on the mass of the active materials of the positive and negative electrodes) in the first week at a 0.5C rate, a charge-discharge efficiency of 80.60% in the first week, an output energy density of 100.42 Wh / kg (based on the mass of the active materials of the positive and negative electrodes), and a capacity retention of 75.09% after 100 cycles. The results are shown in Table 12.

[0195]

[0196] Table 12

[0197] The aqueous battery electrolyte additives described in the above embodiments of the present invention contain salts with large cations or ionic liquids (CX). These additives can enable metal salts to overcome the solubility limit in water, achieving higher solubility and forming an ultra-high concentration aqueous electrolyte. This further broadens the electrochemical window of the electrolyte, inhibits the dissolution of electrode materials, and reduces the corrosion of the current collector by the electrolyte. Simultaneously, a small amount of the additive can be used with a low-concentration metal salt aqueous solution to form a low-concentration aqueous electrolyte. This low-concentration aqueous electrolyte can achieve the same electrochemical window as the high-concentration electrolyte, inhibiting oxygen evolution at the positive electrode and hydrogen evolution at the negative electrode, thus reducing the cost of the aqueous battery electrolyte.

[0198] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An aqueous battery electrolyte, characterized by, The aqueous battery electrolyte comprises an additive; the additive has a chemical formula TX, and is specifically a salt or ionic liquid containing non-hydrated cations; In the TX, T is a non-aqueous cation, including one or more of pyridinium (C5H5NR) + , quaternary phosphonium (R4P) + , triazolium (C2H2N3R2) + , imidazolium (C3H3N2R2) + , pyrrolidinium (C4H8NR2) + , piperidinium (C5H 10 NR2) + , guanidinium (CN3R6) + , oxazolium (C4H8ONR2) + , oxazolidinium (C3H6NOR2) + , amino acid (CH3NO2R2) + , sulfonium (R3S) + ; X is an anion, including one or more of I - , Br - , Cl - , F - , CF3SO3 - , (CF3SO2)2N - , F2N(SO2)2 - , H2PO4 - , RCOO - , BF4 - . The electrolyte is an aqueous solution of a metal salt AE stable in water; in the metal salt AE, A is a cation, including one or more of an alkali metal ion, an alkaline earth metal ion, Zn 2+ or Al 3+ ; E is an anion, including one or more of NO3 - , SO4 2- , Cl - , Br - , PO4 3- , CO3 2- , CH3COO - , CF3SO3 - , TFSI - , FSI - , BETI - , NFN - , BF4 - . During charging of the aqueous battery, the non-hydrated cations in the additive TX form a layer of hydrophobic cation molecular sieve on the surface of the negative electrode of the battery under the action of an electric field, thereby preventing hydrogen evolution on the surface of the negative electrode of the battery; The additive TX is applied in the aqueous battery electrolyte, and the concentration of the additive TX ranges from 0.0001 mol / kg to 5 mol / kg, so that the aqueous battery electrolyte has a stable electrochemical window of greater than 2 V under the condition that the metal salt AE has a low concentration, and the low concentration ranges from 0.0001 mol / kg to 20 mol / kg.

2. The aqueous battery electrolyte of claim 1, wherein, During electrochemical reaction of the aqueous battery, the cations in the metal salt AE are inserted into the positive and negative electrode materials of the battery, and the non-hydrated cations in the additive TX are not inserted into the positive and negative electrode materials of the battery.

3. An aqueous battery electrolyte, characterized by, The aqueous battery electrolyte comprises an additive; the additive has a chemical formula TX, and is specifically a salt or ionic liquid containing non-hydrated cations; In the TX, T is a non-aqueous cation, including one or more of a pyridinium cation (C5H5NR) + , a phosphonium cation (R4P) + , a triazolium cation (C2H2N3R2) + , an imidazolium cation (C3H3N2R2) + , a pyrrolidinium cation (C4H8NR2) + , a piperidinium cation (C5H 10 NR2) + , a guanidinium cation (CN3R6) + , a morpholinium cation (C4H8ONR2) + , an oxazolidinium cation (C3H6NOR2) + , an amino acid cation (CH3NO2R2) + , a sulfonium cation (R3S) + ; X is an anion, including one or more of I - , Br - , Cl - , F - , CF3SO3 - , (CF3SO2)2N - , F2N(SO2)2 - , H2PO4 - , RCOO - , BF4 - . The electrolyte is an aqueous solution of a metal salt AE stable in water; in the metal salt AE, A is a cation, including one or more of an alkali metal ion, an alkaline earth metal ion, Zn 2+ or Al 3+ ; E is an anion, including one or more of NO3 - , SO4 2- , Cl - , Br - , PO4 3- , CO3 2- , CH3COO - , CF3SO3 - , TFSI - , FSI - , BETI - , NFN - , BF4 - . During charging of the aqueous battery, the non-hydrated cations in the additive TX form a layer of hydrophobic cation molecular sieve on the surface of the negative electrode of the battery under the action of an electric field, thereby preventing hydrogen evolution on the surface of the negative electrode of the battery; The additive is applied in the aqueous battery electrolyte, and the concentration of the additive TX ranges from 0.0001 mol / kg to 100 mol / kg, so that the solubility of the metal salt AE in water is improved, and the solubility of the metal salt AE in water is increased from a low solubility of not more than 20 mol / kg without the additive TX to a high solubility of up to 100 mol / kg.

4. The aqueous battery electrolyte of claim 3, wherein, During electrochemical reaction of the aqueous battery, the cations in the metal salt AE are inserted into the positive and negative electrode materials of the battery, and the non-hydrated cations in the additive TX are not inserted into the positive and negative electrode materials of the battery.

5. A battery, characterized by The battery comprises the aqueous battery electrolyte, the positive electrode material and the negative electrode material according to any one of claims 1 to 4.

6. The battery of claim 5, wherein, LiMn2O4, LiFePO4, LiCoO2, LiNi x Co y Mn 1-x-y O2, LiNi x Co y Al 1-x-y O2; the negative electrode material includes any one of anatase TiO2, TiO2(B), Mo6S8, Li4Ti5O 12 , LiTi2(PO4)3.

7. The battery of claim 5, wherein, The battery specifically comprises 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.

8. Use of a battery as claimed in claim 5, characterized in that The battery is applied in a power storage station, a mobile power supply of a portable device, a power device of an electric vehicle and a hybrid electric vehicle.

Images