Lithium ion battery with copper-based conversion type positive electrode material and preparation method

Abstract

The invention discloses a lithium ion battery with a copper-based conversion type positive electrode material and a preparation method. The lithium ion battery with the copper-based conversion type positive electrode material comprises a positive electrode, a negative electrode and a solid electrolyte arranged between the positive electrode and the negative electrode, an active material of the positive electrode comprises at least one of CuCl2, CuF2 and CuBr2; liquid electrolyte is filled between the solid electrolyte and the positive electrode and between the solid electrolyte and the negative electrode; the liquid electrolyte comprises a lithium salt and an ether solvent, and the concentration of the lithium salt in the liquid electrolyte is 4-12M. The liquid electrolyte and the solid electrolyte are combined to construct the mixed electrolyte, and the liquid electrolyte has high lithium salt concentration and weak solvation ability, can inhibit dissolution of an active material and effectively wet an interface, and can effectively relieve dissolution and shuttle effects of a copper-based positive electrode in cooperation with the solid electrolyte.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and more specifically, to a lithium-ion battery having a copper-based conversion cathode material and a method for its preparation. Background Technology

[0002] Lithium-ion batteries hold a key position in the electrochemical energy storage market, widely used in portable electronic devices, electric vehicles, and emerging large-scale energy storage systems. Commercial lithium-ion batteries typically employ intercalation-type cathodes, achieving stable charge-discharge cycles through the insertion and extraction of lithium ions within a crystal structure. Common materials include layered oxides (such as LiCoO2 and LiNi). x Co y Mn 1-x-y O2), spinel oxides (such as LiMn2O4), and polyanionic oxides (such as LiFePO4). These materials can reversibly insert and extract lithium ions at relatively high operating voltages, but their energy density is limited due to the limited number of lithium ion insertion sites in the lattice, making it difficult to meet the ever-increasing energy demands.

[0003] Conversion materials, through multiple electron transfer reactions, can achieve high specific capacity and energy density, showing great research potential. Among them, copper-based materials such as CuCl2 are particularly promising due to their cost-effectiveness and high specific capacity (399 mAh g⁻¹). -1 Its high theoretical specific capacitance and operating potentials of 3.41V and 2.74V have attracted widespread attention.

[0004] However, the high solubility of copper-based materials such as CuCl2 in conventional organic electrolyte systems leads to problems such as loss of active materials, battery self-discharge, and capacity decay, greatly limiting its practical application as a cathode material. Currently, researchers are attempting to effectively suppress CuCl2 dissolution and reduce its self-discharge by using low-dielectric-constant electrolytes combined with the construction of a cathode interface layer. Furthermore, a composite material strategy, filling active CuCl2 into ordered mesoporous carbon, can also achieve a reversible two-electron transfer reaction. However, after dozens of charge-discharge cycles, the battery exhibits severe capacity decay, and copper deposition can be detected on the lithium metal anode side.

[0005] Therefore, in order to realize the practical application of copper-based cathode materials in lithium-ion batteries, an electrolyte system that can suppress or even eliminate dissolution and shuttle effects is particularly necessary. Summary of the Invention

[0006] The purpose of this invention is to provide a lithium-ion battery with copper-based conversion cathode material and a method for its preparation, and to provide an electrolyte system that can suppress or even eliminate the dissolution and shuttle effect of copper-based cathode material.

[0007] This invention is implemented as follows:

[0008] In a first aspect, the present invention provides a lithium-ion battery having a copper-based conversion cathode material, comprising a cathode, a negative electrode, and a solid electrolyte disposed between the cathode and the negative electrode;

[0009] The active material of the positive electrode includes at least one of CuCl2, CuF2, and CuBr2;

[0010] Liquid electrolyte is filled between the solid electrolytic cell and the positive electrode, and between the solid electrolyte and the negative electrode.

[0011] The liquid electrolyte comprises lithium salt and ether solvent, wherein the concentration of lithium salt in the liquid electrolyte is 4M to 12M.

[0012] In an optional embodiment, the ether solvent is at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether;

[0013] And / or, the lithium salt in the liquid electrolyte is at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, and lithium difluorooxalate borate.

[0014] In an optional embodiment, the negative electrode material is at least one of lithium metal and lithium indium alloy.

[0015] In an optional embodiment, a polymer buffer layer is provided on the side of the solid electrolyte near the negative electrode. The raw materials of the polymer buffer layer include polymer, lithium salt and succinic anionylene, wherein the polymer is at least one of poly(vinylidene fluoride-co-hexafluoropropylene) and polyoxyethylene.

[0016] In an optional embodiment, the mass ratio of polymer to lithium salt in the raw materials of the polymer buffer layer is (1-2):1;

[0017] In an optional embodiment, the mass of succinic anion is 5% to 10% of the total mass of the polymer and lithium salt in the raw material of the polymer buffer layer.

[0018] In an optional embodiment, the solid electrolyte is at least one of LLTO, LLZO, LLZTO, LAGP, and LATP.

[0019] In an optional embodiment, the preparation method of the solid electrolyte includes: pressing LAGP or LATP powder into sheets and then sintering them; wherein the pressing pressure is 3MPa-6MPa, the sintering temperature is 850℃-950℃, and the sintering time is 3h-12h.

[0020] Secondly, the present invention provides a method for preparing a lithium-ion battery having a copper-based conversion cathode material as described in any one of the foregoing embodiments, comprising:

[0021] The positive electrode, negative electrode, and solid electrolyte are assembled together, and liquid electrolyte is filled on both sides of the solid electrolyte to obtain the lithium-ion battery with copper-based conversion positive electrode material.

[0022] In an optional embodiment, a polymer buffer layer is provided on the side of the solid electrolyte near the negative electrode. The preparation method of the polymer buffer layer includes: spreading a polymer solution containing polymer buffer layer raw materials on one side of the solid electrolyte and then drying it. The drying temperature is 50℃-100℃ and the drying time is 1h-6h to obtain a solid electrolyte with polymer buffer.

[0023] And / or, the amount of liquid electrolyte added is 2ul-10ul.

[0024] The present invention has the following beneficial effects:

[0025] This application combines liquid electrolytes and solid electrolytes to construct a hybrid electrolyte, wherein the liquid electrolyte has a high lithium salt concentration and weak solvation ability, which can inhibit the dissolution of active materials and effectively wet the interface. When combined with the solid electrolyte, it can effectively alleviate the dissolution and shuttle effect of copper-based cathodes. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The solubility of CuCl2 in different solutions;

[0028] Figure 2 The copper content in ether electrolytes of different concentrations;

[0029] Figure 3 The Nyquist plot and corresponding Arrhenius plot of the mixed electrolyte of Example 1 at 30°C to 80°C;

[0030] Figure 4 The Nyquist plots of the mixed electrolyte in Example 1 before and after polarization are shown (the inset is the current-time curve at 10mV polarization).

[0031] Figure 5The graph shows the electrochemical performance of the lithium-ion battery in Example 1.

[0032] Figure 6 The SEM and EDS surface scans of copper elements on the negative electrode side after cycling in Example 1 and Comparative Example 3 are shown.

[0033] Figure 7 The graphs show the electrochemical performance of the lithium-ion batteries in Examples 4 and 5. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0035] This invention provides a lithium-ion battery with a copper-based conversion cathode material, comprising a cathode, a cathode, and a solid electrolyte disposed between the cathode and the cathode;

[0036] The active material of the positive electrode includes at least one of CuCl2, CuF2, and CuBr2;

[0037] Liquid electrolyte is filled between the solid electrolytic cell and the positive electrode, and between the solid electrolyte and the negative electrode.

[0038] The liquid electrolyte comprises lithium salt and ether solvent, wherein the concentration of lithium salt in the liquid electrolyte is 4M to 12M.

[0039] This application combines liquid electrolytes and solid electrolytes to construct a hybrid electrolyte, wherein the liquid electrolyte has a high lithium salt concentration and weak solvation ability, which can inhibit the dissolution of active materials and effectively wet the interface. When combined with the solid electrolyte, it can effectively alleviate the dissolution and shuttle effect of copper-based cathodes.

[0040] In an optional embodiment, the ether solvent is at least one of ethylene glycol dimethyl ether and diethylene glycol dimethyl tetraethylene glycol dimethyl ether;

[0041] And / or, the lithium salt in the liquid electrolyte is at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, and lithium difluorooxalate borate.

[0042] In an optional embodiment, a polymer buffer layer is provided on the side of the solid electrolyte near the negative electrode. The raw materials of the polymer buffer layer include polymer, lithium salt and succinic anionylene, wherein the polymer is at least one of poly(vinylidene fluoride-co-hexafluoropropylene) and polyoxyethylene. The presence of the polymer buffer layer helps to avoid direct contact between the electrolyte and lithium metal and helps to reduce side reactions.

[0043] In an optional embodiment, the mass ratio of polymer to lithium salt in the raw materials of the polymer buffer layer is (1-2):1;

[0044] In an optional embodiment, the mass of succinic anion is 5% to 10% of the total mass of the polymer and lithium salt in the raw material of the polymer buffer layer.

[0045] In an optional embodiment, the solid electrolyte is at least one of LLTO, LLZO, LLZTO, LAGP, and LATP.

[0046] In an optional embodiment, the preparation method of the solid electrolyte includes: pressing LAGP or LATP powder into sheets and then sintering them; wherein the pressing pressure is 3MPa-6MPa; the sintering temperature is 850℃-950℃; and the sintering time is 3h-12h.

[0047] The present invention also provides a method for preparing a lithium-ion battery having a copper-based conversion cathode material as described in any one of the foregoing embodiments, comprising:

[0048] The positive electrode, negative electrode, and solid electrolyte are assembled together, and liquid electrolyte is filled on both sides of the solid electrolyte to obtain the lithium-ion battery with copper-based conversion positive electrode material.

[0049] In an optional embodiment, a polymer buffer layer is provided on the side of the solid electrolyte near the negative electrode. The preparation method of the polymer buffer layer includes: spreading a polymer solution containing polymer buffer layer raw materials on one side of the solid electrolyte and then drying it. The drying temperature is 50℃-100℃ and the drying time is 1h-6h to obtain a solid electrolyte with polymer buffer.

[0050] And / or, the amount of liquid electrolyte added is 2ul-10ul.

[0051] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0052] Example 1

[0053] This embodiment provides a method for preparing a lithium-ion battery with a copper-based conversion cathode material, specifically including the following steps:

[0054] 0.3 g of poly(vinylidene fluoride-co-hexafluoropropylene), 0.3 g of lithium bis(trifluoromethanesulfonyl)imide, and 0.015 g of succinate were dissolved in 3 ml of dimethylformamide to obtain a polymer solution. 3 g of lithium bis(trifluoromethanesulfonyl)imide was dissolved in ethylene glycol dimethyl ether to obtain an 8 M liquid electrolyte. LAGP powder was ground in an agate mortar and sieved through a 100-mesh sieve. 0.4 g of powder was placed in a 15 mm diameter mold and pressed into a sheet shape under a pressure of 4 MPa. The pressed green body was placed in an alumina crucible and then sintered in a muffle furnace at 900 °C for 8 h to obtain LAGP ceramic sheets. 8 μL of polymer solution was added dropwise to one side of the LAGP using a pipette, and the sheet was dried at 80 °C for 1 h to obtain a LAGP solid electrolyte with a polymer buffer layer.

[0055] CuCl2 and carbon black were ball-milled at a mass ratio of 4:1 for 1 hour to obtain active powder. The active powder, KB and polyvinylidene fluoride binder were used to prepare a positive electrode sheet at a mass ratio of 80:10:10. The lithium sheet was used as the negative electrode. 7 μL of 8M liquid electrolyte was added to the positive electrode side and 2 μL of liquid electrolyte was added to the negative electrode side. LAGP was used as an electrolyte interlayer to obtain a solid-liquid mixed electrolyte, in which the polymer buffer layer faced the lithium metal negative electrode. The cells were then assembled into a coin cell.

[0056] Example 2

[0057] This embodiment provides a method for preparing a lithium-ion battery with a copper-based conversion cathode material, specifically including the following steps:

[0058] 0.3 g of poly(vinylidene fluoride-co-hexafluoropropylene), 0.3 g of lithium bis(trifluoromethanesulfonyl)imide, and 0.03 g of succinate were mixed and dissolved in 3 ml of dimethylformamide to obtain a polymer solution. 4.5 g of lithium bis(trifluoromethanesulfonyl)imide salt was dissolved in ethylene glycol dimethyl ether to obtain a 12 M liquid electrolyte. LAGP powder was ground in an agate mortar and sieved through a 100-mesh sieve. 0.4 g of powder was placed in a 15 mm diameter mold and pressed into a sheet shape under a pressure of 4 MPa. The pressed green body was placed in an alumina crucible and then sintered in a muffle furnace at 900 °C for 8 h to obtain LAGP ceramic sheets. 8 μL of polymer solution was added dropwise to one side of the LAGP sheet using a pipette, and the sheet was dried at 80 °C for 1 h to obtain a LAGP solid electrolyte with a polymer buffer layer.

[0059] CuCl2 and carbon black were ball-milled at a mass ratio of 4:1 for 1 hour to obtain active powder. The active powder, KB, and polyvinylidene fluoride binder were used to prepare the positive electrode at a mass ratio of 80:10:10. A lithium sheet was used as the negative electrode. 8 μL of 12M liquid electrolyte was added to the positive electrode side, and 2 μL of liquid electrolyte was added to the negative electrode side. LAGP was used as an electrolyte interlayer to obtain a mixed electrolyte, with the polymer buffer layer facing the lithium metal negative electrode side. This mixture was then assembled into a coin cell.

[0060] Example 3

[0061] This embodiment provides a method for preparing a lithium-ion battery with a copper-based conversion cathode material, specifically including the following steps:

[0062] 0.3 g of poly(vinylidene fluoride-co-hexafluoropropylene), 0.3 g of lithium difluoromethanesulfonylimide, and 0.03 g of succinate were dissolved in 3 ml of dimethylformamide to obtain a polymer solution. 3 g of lithium difluoromethanesulfonylimide salt was dissolved in ethylene glycol dimethyl ether to obtain an 8 M liquid electrolyte. LATP powder was ground in an agate mortar and sieved through a 100-mesh sieve. 0.4 g of powder was placed in a 15 mm diameter mold and pressed into a sheet shape under a pressure of 6 MPa. The pressed green body was placed in an alumina crucible and then sintered in a muffle furnace at 900 °C for 3 h to obtain LATP ceramic sheets. 8 μL of polymer solution was added dropwise to one side of the LATP using a pipette, and the sheet was dried at 80 °C for 2 h to obtain a LAGP solid electrolyte with a polymer buffer layer.

[0063] CuCl2 and carbon black were ball-milled at a mass ratio of 4:1 for 1 hour to obtain active powder. The active powder, KB, and polyvinylidene fluoride binder were used to prepare the positive electrode at a mass ratio of 80:10:10. A lithium sheet was used as the negative electrode. 7 μL of 8M liquid electrolyte was added to the positive electrode side, and 2 μL of liquid electrolyte was added to the negative electrode side. LATP was used as an electrolyte interlayer to obtain a solid-liquid mixed electrolyte, with the polymer buffer layer facing the lithium metal negative electrode. This mixture was then assembled into a coin cell.

[0064] Example 4

[0065] This embodiment provides a method for preparing a lithium-ion battery with a copper-based conversion cathode material, specifically including the following steps: 0.3g of poly(vinylidene fluoride-co-hexafluoropropylene), 0.3g of lithium bis(trifluoromethanesulfonyl)imide, and 0.015g of succinate are mixed and dissolved in 3ml of dimethylformamide to obtain a polymer solution; 3g of lithium bis(trifluoromethanesulfonyl)imide is dissolved in ethylene glycol dimethyl ether to obtain an 8M liquid electrolyte. LAGP powder is ground in an agate mortar, sieved through a 100-mesh sieve, and 0.4g of powder is placed into a mold with a diameter of 15mm and pressed into a sheet shape under a pressure of 4MPa. The pressed green body is placed in an alumina crucible and then sintered in a muffle furnace at 900℃ for 8h to obtain LAGP ceramic sheets. 8ul of polymer solution is added dropwise to one side of the LAGP using a pipette, and the sheet is dried at 80℃ for 1h to obtain a LAGP solid electrolyte with a polymer buffer layer.

[0066] CuF2 and carbon black were ball-milled at a mass ratio of 4:1 for 1 hour to obtain active powder. The active powder, KB and polyvinylidene fluoride binder were prepared into a positive electrode at a mass ratio of 80:10:10. Lithium sheet was used as the negative electrode. 7 μL of 8M liquid electrolyte was added to the positive electrode side and 2 μL of liquid electrolyte was added to the negative electrode side. LAGP was used as an electrolyte interlayer to obtain a solid-liquid mixed electrolyte, in which the polymer buffer layer faced the lithium metal negative electrode. The cells were then assembled into a coin cell.

[0067] Example 5

[0068] This embodiment provides a method for preparing a lithium-ion battery with a copper-based conversion cathode material, specifically including the following steps: 0.3g of poly(vinylidene fluoride-co-hexafluoropropylene), 0.3g of lithium bis(trifluoromethanesulfonyl)imide, and 0.015g of succinate are mixed and dissolved in 3ml of dimethylformamide to obtain a polymer solution; 3g of lithium bis(trifluoromethanesulfonyl)imide is dissolved in ethylene glycol dimethyl ether to obtain an 8M liquid electrolyte. LAGP powder is ground in an agate mortar, sieved through a 100-mesh sieve, and 0.4g of powder is placed into a mold with a diameter of 15mm and pressed into a sheet shape under a pressure of 4MPa. The pressed green body is placed in an alumina crucible and then sintered in a muffle furnace at 900℃ for 8h to obtain LAGP ceramic sheets. 8ul of polymer solution is added dropwise to one side of the LAGP using a pipette, and the sheet is dried at 80℃ for 1h to obtain a LAGP solid electrolyte with a polymer buffer layer.

[0069] CuBr2 and carbon black were ball-milled at a mass ratio of 4:1 for 1 hour to obtain active powder. The active powder, KB, and polyvinylidene fluoride binder were then used to prepare the positive electrode at a mass ratio of 80:10:10. Using CuBr2 as the positive electrode and lithium foil as the negative electrode, 7 μL of 8M liquid electrolyte was added to the positive electrode side and 2 μL to the negative electrode side. LAGP was used as the electrolyte interlayer to obtain a solid-liquid hybrid electrolyte, with the polymer buffer layer facing the lithium metal negative electrode. This mixture was then assembled into a coin cell.

[0070] Comparative Example 1

[0071] This comparative example provides a method for preparing a lithium-ion battery with a copper-based conversion cathode material. The only difference from Example 1 is that the concentration of the liquid electrolyte is 1M.

[0072] Comparative Example 2

[0073] This comparative example provides a method for preparing a lithium-ion battery with a copper-based conversion cathode material. The only difference from Example 1 is that the concentration of the liquid electrolyte is 2M.

[0074] Comparative Example 3

[0075] This comparative example provides a method for preparing a lithium-ion battery with a copper-based conversion cathode material, differing from Example 1 only in that it uses only a liquid electrolyte. 3g of lithium difluorosulfonylimide salt was dissolved in ethylene glycol dimethyl ether to obtain an 8M liquid electrolyte. Using CuCl2 as the cathode and a lithium sheet as the anode, 180µl of the 8M liquid electrolyte was added dropwise to assemble a coin cell.

[0076] Test case

[0077] 1) Dissolution experiment:

[0078] 0.1 g of CuCl2 was added to 3 ml of different solvents, and the color changes of the solutions were observed and photographed after standing for 24 h. 0.1 g of CuCl2 was also added to 3 ml of ether electrolytes of different concentrations, and the copper content in the solutions was detected using ICP-MS after standing for 24 h.

[0079] 2) Electrochemical impedance spectroscopy:

[0080] Electrochemical impedance spectroscopy (EIS) was performed using an Autolab PGSTAT302N potentiostat / galvanostat, with a frequency range of 1 MHz to 0.1 Hz and an amplitude of 0.01 V. When determining ionic conductivity using AC impedance spectroscopy, stainless steel sheets were used for both the positive and negative electrodes of the battery.

[0081] 3) Timing current test:

[0082] Chronoamperometry was performed using a CHI760E electrochemical workstation from Shanghai Chenhua Instruments Co., Ltd., and the lithium-ion transference number of the electrolyte was determined using AC impedance spectroscopy. During the test, both the positive and negative electrodes of the battery were lithium metal, the potential step was 10 mV (DC), and the test duration was 20,000 seconds.

[0083] 4) Constant current charge-discharge test:

[0084] Constant current charge-discharge tests were conducted using the BTS-5 battery testing system from Shenzhen Xinwei Electronics Co., Ltd. Before the long-cycle test, the battery was activated by running at 0.05C for 5 cycles, and then continuously cycled at 0.5C.

[0085] 2. Experimental Results

[0086] 1) Dissolution experiment: Figure 1 Optical images showing the dissolution of CuCl2 in different solutions. Figure 1 Image a shows optical images of CuCl2 dissolved in various solvents (dimethyl sulfoxide (DMSO), propylene carbonate (PC), fluoroethylene vinyl carbonate (FEC), and dimethyl glycol ether (DME)). The addition of CuCl2 to polar solvents shows a significant color change, indicating that CuCl2 exhibits strong solubility in polar solvents. Figure 1a). Figure 1 Optical images of bCuCl2 dissolved in ethylene glycol dimethyl ether electrolytes with different concentrations of lithium bis(fluorosulfonyl)imide. The color of the solution lightens as the lithium salt concentration of these electrolytes increases, and approaches clarity at 8 M. Figure 2 The copper content of CuCl2 dissolved in ethylene glycol dimethyl ether electrolytes with different concentrations of lithium difluorosulfonylimide salts was measured to reach saturation. The copper content decreased significantly with increasing concentration, from 991.81 mg kg-1 (1M) to 2.07 mg kg-1 (8M), indicating that high-concentration electrolytes can alleviate the problem of CuCl2 dissolution.

[0087] 2) Activation energy for ion transport:

[0088] Figure 3 These are the Nyquist plots and corresponding Arrhenius plots of the Li-CuCl2 battery assembled using a mixed electrolyte in Example 1 at temperatures ranging from 30°C to 80°C. Figure 2 As shown, the impedance of the mixed electrolyte gradually decreases with increasing temperature. The activation energy of ion transport of the mixed electrolyte is 0.27 eV, which is obtained by fitting the Arrhenius formula.

[0089] 3) Lithium-ion transference number:

[0090] Figure 4 The Nyquist plots for the lithium-symmetric battery assembled using the mixed electrolyte in Example 1 are shown before and after polarization (the inset is the current-time curve at 10 mV polarization). Figure 4 As shown, the lithium-ion transference number of the mixed electrolyte is 0.86.

[0091] 4) Electrochemical performance testing: Figure 5 The graph shows the electrochemical performance of the lithium-ion battery in Example 1. Figure 5 a is 0.05C (1C = 400mAh g) -1 The charge-discharge curves under ( ). Figure 5 c represents the battery's cycle performance at 0.5C. (For example...) Figure 5 As shown in the constant current charge-discharge curve of a, the battery can achieve a high efficiency of 806.6 Wh / kg at 0.05C. -1 It has a high positive electrode energy density and an energy efficiency of up to 95.7%. Figure 5 b shows the rate performance of the battery. At 0.05, 0.1, 0.2, 0.5, and 1C, the discharge specific capacities are 275.6, 251.6, 236.8, 203.7, and 168.0 mAh g, respectively. -1 . Figure 5 c represents the cycle performance of the battery at 0.5C, with an initial specific capacity of 226.6 mAh g for CuCl2. -1It retains 77.9% of its initial specific capacity after 400 cycles at 30°C. Figure 7 The graphs show the electrochemical performance of the lithium-ion batteries in Examples 4 and 5. Figure 7 As can be seen from the data, the specific capacity of the lithium-ion battery in the first discharge cycle in Examples 4 and 5 is close to the theoretical specific capacity of copper fluoride and copper bromide, indicating that the mixed electrolyte of this application also has a good effect on suppressing the dissolution and shuttle of copper fluoride and copper bromide.

[0092] 5) Morphological characterization before and after cycling

[0093] Figure 6 The images show SEM images and EDS copper elemental surface scans of the lithium metal anodes after 100 cycles in Examples 1 and 3. Figure 6 As shown in a and 6b, almost no byproducts accumulated on the lithium metal surface after cycling in Example 1, and the EDS elemental mapping showed only trace amounts of copper signal, verifying the effective suppression of copper ion shuttle by the mixed electrolyte. Conversely, as Figure 6 As shown in c and 6d, a large amount of byproducts accumulated on the surface of the lithium metal after cycling in Comparative Example 3, and dense copper signals were shown in the EDS elemental mapping.

[0094] Table 1

[0095]

[0096] As shown in Table 1, the strategy of using a high-concentration liquid electrolyte combined with a solid electrolyte to construct a hybrid electrolyte is beneficial to improving discharge specific capacity and energy density, and also exhibits excellent cycle stability. However, when using only a high-concentration liquid electrolyte, or a low-concentration liquid electrolyte, the dissolution / shutdown of active materials cannot be sufficiently suppressed, resulting in poor energy density and cycle stability.

[0097] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. 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. A lithium-ion battery having a copper-based conversion cathode material, characterized in that, It includes a positive electrode, a negative electrode, and a solid electrolyte disposed between the positive and negative electrodes; The active material of the positive electrode includes at least one of CuCl2, CuF2, and CuBr2; Liquid electrolyte is filled between the solid electrolytic cell and the positive electrode, and between the solid electrolyte and the negative electrode. The liquid electrolyte comprises lithium salt and ether solvent, wherein the concentration of lithium salt in the liquid electrolyte is 4M to 12M.

2. The lithium-ion battery with copper-based conversion cathode material according to claim 1, characterized in that, The ether solvent is at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether; And / or, the lithium salt in the liquid electrolyte is at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, and lithium difluorooxalate borate.

3. The lithium-ion battery with copper-based conversion cathode material according to claim 1, characterized in that, The negative electrode material is at least one of lithium metal and lithium indium alloy.

4. The lithium-ion battery with copper-based conversion cathode material according to claim 1, characterized in that, A polymer buffer layer is provided on the side of the solid electrolyte near the negative electrode. The raw materials of the polymer buffer layer include polymer, lithium salt and succinic anion, wherein the polymer is at least one of poly(vinylidene fluoride-co-hexafluoropropylene) and polyoxyethylene.

5. The lithium-ion battery with copper-based conversion cathode material according to claim 4, characterized in that, In the raw materials of the polymer buffer layer, the mass ratio of polymer to lithium salt is (1-2):

1.

6. The lithium-ion battery with copper-based conversion cathode material according to claim 4, characterized in that, In the raw materials of the polymer buffer layer, the mass of succinic anion is 5% to 10% of the total mass of the polymer and lithium salt.

7. The lithium-ion battery with copper-based conversion cathode material according to claim 1, characterized in that, The solid electrolyte is at least one of LLTO, LLZO, LLZTO, LAGP, and LATP.

8. The lithium-ion battery with copper-based conversion cathode material according to claim 1, characterized in that, The preparation method of the solid electrolyte includes: pressing LAGP or LATP powder into sheets and then sintering them; wherein the pressing pressure is 3MPa-6MPa; the sintering temperature is 850℃-950℃; and the sintering time is 3h-12h.

9. A method for preparing a lithium-ion battery having a copper-based conversion cathode material as described in any one of claims 1-8, characterized in that, include: The positive electrode, negative electrode, and solid electrolyte are assembled together, and liquid electrolyte is filled on both sides of the solid electrolyte to obtain the lithium-ion battery with copper-based conversion positive electrode material.

10. The method for preparing a lithium-ion battery with a copper-based conversion cathode material according to claim 1, characterized in that, The solid electrolyte has a polymer buffer layer on the side near the negative electrode. The preparation method of the polymer buffer layer includes: spreading a polymer solution containing polymer buffer layer raw materials on one side of the solid electrolyte and drying it. The drying temperature is 50℃-100℃ and the drying time is 1h-6h to obtain a solid electrolyte with polymer buffer. And / or, the amount of liquid electrolyte added is 2ul-10ul.

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