Lithium-copper composite negative electrode prepared from lithium slag

Abstract

The invention discloses a method for preparing a lithium-copper composite negative electrode by utilizing lithium slag and application, and the preparation method of the negative electrode comprises the following steps: adding the lithium slag with certain concentration after removing impurities such as Ca < 2 + >, Mg < 2 + > and Fe < 3 + > through acid treatment into metal lithium in a molten state, and fully stirring until the reaction is complete; and coating the molten metal lithium obtained after the reaction on a current collector to obtain the modified lithium metal negative electrode plate. The prepared lithium-copper composite negative electrode has a lithium-loving 3D frame structure, volume expansion in the circulation process can be inhibited, lithium oxide, lithium aluminum alloy and lithium silicon alloy existing on the 3D frame structure can serve as lithium-loving sites for uniform lithium ion deposition, lithium dendrite growth is inhibited, and long-term stable circulation of the lithium metal negative electrode is promoted.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of comprehensive utilization of solid waste lithium ore slag and lithium metal battery negative electrode material and electrochemistry, and particularly relates to a method for preparing lithium-copper composite negative electrode from lithium ore slag and application thereof. BACKGROUND

[0002] Nowadays, with the vigorous development of new energy industries such as electric vehicles, the demand for lithium resources has rapidly increased, and a large amount of lithium ore has been consumed to produce lithium carbonate, while a large amount of solid waste lithium ore slag has been generated. At present, the treatment of lithium ore slag mainly relies on open-air stacking and landfill methods. Such treatment methods not only occupy a large amount of land resources, but also pollute the soil, water resources and air, causing damage to the ecological environment.

[0003] At the same time, the energy density of traditional lithium-ion batteries gradually cannot meet people's needs, and the research and development of materials with higher energy density have become a hot spot. Lithium metal negative electrode is considered to be an ideal choice for the next generation of high-energy density batteries due to its high theoretical specific capacity (3860 mAh / g), low density (0.534 g / cm 3 ) and the lowest electrochemical potential (-3.04 V vs. standard hydrogen electrode). However, lithium metal negative electrode has many difficulties in practical application due to problems such as dendrite growth and consumption of active lithium by electrode surface side reactions during actual cycling. In view of these problems, researchers have explored a large number of improvement methods. For example, constructing an artificial interface layer, developing a new type of electrolyte, designing a three-dimensional structure negative electrode and other methods to solve the problems of lithium metal negative electrode. For example, Liang cao et al. prepared a multifunctional composite lithium metal negative electrode with excellent electrochemical performance by a strategy of molten infusion of SnS2 into molten lithium metal. The in-situ formed Li2S / Li 22 Sn5 three-dimensional framework contains a large amount of Li2S phase to promote uniform lithium ion deposition, Li 22 Sn5 phase promotes rapid charge transfer, thereby inhibiting lithium dendrite growth, and exhibits excellent performance at high current density. (Adv. Mater. 2024, 36, 2406034)

[0004] The present application uses lithium ore slag after acid treatment to prepare lithium metal negative electrode, which solves the problem of waste lithium ore slag treatment while realizing stable lithium metal negative electrode and protecting the ecological environment. SUMMARY

[0005] The purpose of the present application is to solve the problems of low coulomb efficiency, poor cycle performance and safety performance caused by dendrite growth and dead lithium of lithium metal negative electrode during charging and discharging process due to the high activity of lithium metal and the uneven deposition of lithium ions, and to provide a method for preparing lithium-copper composite negative electrode from lithium slag and its application. The lithium-copper composite negative electrode prepared has nucleophilic sites of lithium, which can uniformly deposit lithium ions, inhibit lithium dendrite growth and promote long-term stable cycle of lithium metal negative electrode.

[0006] The present application adopts the following technical solutions:

[0007] A method for preparing lithium-copper composite negative electrode from lithium slag, comprising the following steps:

[0008] (1) treating lithium slag with acid of a certain concentration for a period of time, filtering and washing the product, and drying it in an oven;

[0009] (2) heating and melting metal lithium to obtain molten metal lithium;

[0010] (3) adding the product in (1) to the obtained molten metal lithium and stirring until complete reaction;

[0011] (4) coating the molten metal lithium obtained in (3) on a current collector and cooling to room temperature to obtain a negative electrode sheet.

[0012] Further, the source of the lithium slag used is one of spodumene (containing Li2O 5.8%~8.1%), lepidolite (containing Li2O 3.2%~6.45%), lithiophorite (containing Li2O 7.1%~10.1%), petalite (containing Li2O 2.9%~4.8%) and iron lepidolite (containing Li2O 1.1%~5%).

[0013] Further, the lithium content of the lithium slag used is less than 0.3%.

[0014] Further, the acid used in step (1) is one of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid.

[0015] Further, the heating temperature of the metal lithium in steps (2) and (3) is 180-260℃.

[0016] Further, the stirring time in step (3) is 10-30min.

[0017] Further, the addition amount of the product in step (3) is 0%-30% of the total mass.

[0018] Further, the negative electrode current collector is copper foil, tin-plated copper foil, aluminum foil or carbon flexible material.

[0019] Further, the heating and stirring process are both completed under a protective gas atmosphere.

[0020] Further, the protective atmosphere is helium, neon, nitrogen or argon atmosphere.

[0021] The application also provides the application of the above lithium-copper composite negative electrode, which is used for assembling into a lithium metal battery, wherein the lithium metal battery comprises a positive electrode, the prepared lithium-copper composite negative electrode, a separator and an electrolyte.

[0022] Further, the material of the positive electrode comprises lithium iron phosphate (LiFePO4), lithium cobaltate (LiCoO2), ternary material (LiNi x Co y Mn 1-y O2, 0≤x≤1, 0≤y≤1), lithium nickel-manganese acid (LiNi 0.5 Mn 1.5 O4).

[0023] Further, the separator is a glass fiber membrane (GF membrane), a polyethylene membrane (PE membrane), a polypropylene membrane (PP membrane), a polyethylene / polypropylene double-layer co-extrusion membrane (PP / PE membrane) or a polypropylene / polyethylene / polypropylene three-layer co-extrusion membrane (PP / PE / PP membrane).

[0024] Further, the electrolyte is an ester electrolyte or an ether electrolyte.

[0025] Compared with the prior art, the application has the following advantages and technical effects:

[0026] (1) The lithium-copper composite negative electrode prepared by the application has a lithium-philic 3D framework structure, which can inhibit the volume expansion in the cycle process, and the lithium oxide, lithium-aluminum alloy and lithium-silicon alloy existing on the 3D framework structure can be used as lithium-philic sites to uniformly deposit lithium ions and inhibit lithium dendrite growth, thereby promoting the long-term stable cycle of the lithium metal negative electrode.

[0027] (2) The application uses lithium slag as raw material, which reduces the production cost and realizes the recycling of lithium slag, thereby reducing the environmental pollution and land occupation caused by the treatment of lithium slag.

[0028] (3) The preparation process of the application is simple, the production cost is low, and the industrial production is facilitated. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 XRD of the lithium slag after acid treatment.

[0030] Figure 2 Constant current cycle diagram of the lithium-copper composite electrode prepared in Example 6 matched with lithium iron phosphate positive electrode material to assemble into a full battery.

[0031] Figure 3 Time-voltage curve of the lithium copper composite electrode prepared in Example 8 assembled into a symmetric battery Li||Li.

[0032] Figure 4 Actual picture of the lithium copper composite negative electrode prepared in Example 8.

[0033] Figure 5 Thickness (unit: mm) of the lithium copper composite negative electrode prepared. DETAILED DESCRIPTION

[0034] The present application is further illustrated in detail by the following examples, but is not limited to the examples.

[0035] The experimental methods in the following examples are all conventional methods unless otherwise specified.

[0036] Example 1

[0037] (1) The metallic lithium was heated to 250°C under a protective atmosphere to be in a molten state;

[0038] (2) The molten metallic lithium in (1) was uniformly coated onto a tin-plated copper foil and cooled to room temperature to obtain a negative electrode sheet.

[0039] The negative electrode sheet was assembled into a Li||Li symmetric battery, and the separator of the Li||Li symmetric battery was a PE separator, and the electrolyte was a commercial ester electrolyte. The Li||Li symmetric battery was tested under the conditions of a current density of 1 mA / cm 2 , and a deposition capacity of 1 mAh / cm 2 . The stable cycle was 400 h, the polarization voltage was lower than 100 mV, and the voltage platform was symmetrical.

[0040] Example 2

[0041] (1) The lithium slag was added into 1 mol / L dilute hydrochloric acid and reacted for 24 h, and the reaction product was filtered, washed, and dried for use;

[0042] (2) The metallic lithium was heated to 250°C under a protective atmosphere to be in a molten state;

[0043] (3) The reaction product in (1) was added into the molten lithium at a mass fraction of 5% and stirred for 30 min to complete the reaction;

[0044] (4) The product obtained in (3) was uniformly coated onto a tin-plated copper foil and cooled to room temperature to obtain a negative electrode sheet.

[0045] The negative electrode sheet is assembled into a Li||Li symmetric battery, the separator of the Li||Li symmetric battery is a PE separator, and the electrolyte is a commercial ester electrolyte. The test is carried out under the condition that the current density is 0.5 mA / cm2 and the deposition capacity is 1 mAh / cm2. After 500 h of stable cycle, the polarization voltage is lower than 50 mV, and the voltage platform is symmetrical. It shows that the lithium-copper composite electrode can effectively inhibit the growth of lithium dendrites and exhibits excellent electrochemical stability.

[0046] Example 3

[0047] (1) The lithium slag is added into 1 mol / L dilute hydrochloric acid and reacted for 24 h, and the reaction product is filtered, washed and dried for standby;

[0048] (2) The metallic lithium is heated to 250℃ in a protective atmosphere to be in a molten state;

[0049] (3) The reaction product in (1) is added into the molten lithium at a mass fraction of 7.5% and stirred for 30 min to complete the reaction;

[0050] (4) The product obtained in (3) is uniformly coated on a tinned copper foil and cooled to room temperature to obtain a negative electrode sheet.

[0051] The negative electrode sheet is assembled into a Li||Li symmetric battery, the separator of the Li||Li symmetric battery is a PE separator, and the electrolyte is a commercial ester electrolyte. The test is carried out under the condition that the current density is 0.5 mA / cm 2 , and the deposition capacity is 3 mAh / cm 2 . After 500 h of stable cycle, the polarization voltage is lower than 50 mV, and the voltage platform is symmetrical. It shows that the lithium-copper composite electrode can effectively inhibit the growth of lithium dendrites and exhibits excellent electrochemical stability.

[0052] Example 4

[0053] (1) The lithium slag is added into 1 mol / L dilute hydrochloric acid and reacted for 24 h, and the reaction product is filtered, washed and dried for standby;

[0054] (2) The metallic lithium is heated to 250℃ in a protective atmosphere to be in a molten state;

[0055] (3) The reaction product in (1) is added into the molten lithium at a mass fraction of 10% and stirred for 30 min to complete the reaction;

[0056] (4) The product obtained in (3) is uniformly coated on a tinned copper foil and cooled to room temperature to obtain a negative electrode sheet.

[0057] The negative electrode sheet was assembled into a Li||Li symmetric battery, the separator of the Li||Li symmetric battery was a PE separator, and the electrolyte was a commercial ester electrolyte. The test was carried out under the condition of a current density of 0.5 mA / cm 2 , and a deposition capacity of 1 mAh / cm 2 . The stable cycle was 600 h, the polarization voltage was less than 50 mV, and the voltage platform was symmetrical. It is shown that the lithium-copper composite electrode can effectively inhibit the growth of lithium dendrites and exhibit excellent electrochemical stability.

[0058] Example 5

[0059] (1) Lithium slag was added to 1 mol / L dilute hydrochloric acid and reacted for 24 h, and the reaction product was filtered, washed, and dried for use;

[0060] (2) Metal lithium was heated to 250 DEG C under a protective atmosphere to be in a molten state;

[0061] (3) The reaction product in (1) was added to the molten lithium at a mass fraction of 12.5% and stirred for 30 min to complete the reaction;

[0062] (4) The product obtained in (3) was uniformly coated on a tin-plated copper foil and cooled to room temperature to obtain a negative electrode sheet.

[0063] The negative electrode sheet was assembled into a Li||Li symmetric battery, the separator of the Li||Li symmetric battery was a PE separator, and the electrolyte was a commercial ester electrolyte. The test was carried out under the condition of a current density of 1 mA / cm 2 , and a deposition capacity of 3 mAh / cm 2 . The stable cycle was 500 h, the polarization voltage was less than 100 mV, and the voltage platform was symmetrical. It is shown that the lithium-copper composite electrode can effectively inhibit the growth of lithium dendrites and exhibit excellent electrochemical stability.

[0064] Example 6

[0065] (1) Lithium slag was added to 1 mol / L dilute hydrochloric acid and reacted for 24 h, and the reaction product was filtered, washed, and dried for use;

[0066] (2) Metal lithium was heated to 250 DEG C under a protective atmosphere to be in a molten state;

[0067] (3) The reaction product in (1) was added to the molten lithium at a mass fraction of 15% and stirred for 30 min to complete the reaction;

[0068] (4) The product obtained in (3) was uniformly coated on a tin-plated copper foil and cooled to room temperature to obtain a negative electrode sheet.

[0069] The negative electrode sheet is matched with lithium iron phosphate positive electrode material to assemble a full battery. The separator of the full battery is a PE separator, and the electrolyte is a commercial ester electrolyte. After 300 cycles under the condition of 1C, the capacity retention rate is still 90%, and the charge-discharge curve is shown in Figure 2 . It is shown that the lithium-copper composite negative electrode can effectively inhibit the growth of lithium dendrites and exhibit excellent electrochemical stability.

[0070] Example 7

[0071] (1) Lithium slag is added to 1 mol / L dilute hydrochloric acid and reacted for 24 h. The reaction product is filtered, washed, and dried for use;

[0072] (2) Metal lithium is heated to 250°C under a protective atmosphere to form a molten state;

[0073] (3) The reaction product in (1) is added to the molten lithium at a mass fraction of 17.5% and stirred for 30 min to complete the reaction;

[0074] (4) The product obtained in (3) is uniformly coated on a tin-plated copper foil and cooled to room temperature to obtain a negative electrode sheet.

[0075] The negative electrode sheet is assembled into a Li||Li symmetric battery. The separator of the Li||Li symmetric battery is a PE separator, and the electrolyte is a commercial ester electrolyte. Under the condition of a current density of 0.5 mA / cm 2 , and a deposition capacity of 5 mAh / cm 2 , the polarization voltage is less than 50 mV, and the voltage platform is symmetrical after 800 h of stable cycling. It is shown that the lithium-copper composite electrode can effectively inhibit the growth of lithium dendrites and exhibit excellent electrochemical stability.

[0076] Example 8

[0077] (1) Lithium slag is added to 1 mol / L dilute hydrochloric acid and reacted for 24 h. The reaction product is filtered, washed, and dried for use;

[0078] (2) Metal lithium is heated to 250°C under a protective atmosphere to form a molten state;

[0079] (3) The reaction product in (1) is added to the molten lithium at a mass fraction of 20% and stirred for 30 min to complete the reaction;

[0080] (4) The product obtained in (3) is uniformly coated on a tin-plated copper foil and cooled to room temperature to obtain a negative electrode sheet.

[0081] The negative electrode sheet is assembled into a Li||Li symmetric battery. The separator of the Li||Li symmetric battery is a PE separator, and the electrolyte is a commercial ester electrolyte. Under the condition of a current density of 0.5 mA / cm 2, deposition capacity of 1mAh / cm 2 The time-voltage curve of 900h stable cycle is shown in Figure 6. The polarization voltage of the lithium copper composite electrode is less than 50mV, and the voltage platform is symmetrical. It shows that the lithium copper composite electrode can effectively inhibit the growth of lithium dendrites, and exhibits excellent electrochemical stability. Figure 3 The time-voltage curve of 900h stable cycle is shown in Figure 6. The polarization voltage of the lithium copper composite electrode is less than 50mV, and the voltage platform is symmetrical. It shows that the lithium copper composite electrode can effectively inhibit the growth of lithium dendrites, and exhibits excellent electrochemical stability.

[0082] Example 9

[0083] (1) The lithium slag was added to 1mol / L dilute hydrochloric acid and reacted for 24h. The reaction product was filtered, washed and dried for use;

[0084] (2) The metallic lithium was heated to 250℃ in a protective atmosphere to form a molten state;

[0085] (3) The reaction product in (1) was added to the molten lithium at a mass fraction of 22.5% and stirred for 30min to complete the reaction;

[0086] (4) The product obtained in (3) was uniformly coated on a tin-plated copper foil and cooled to room temperature to obtain a negative electrode sheet.

[0087] The negative electrode sheet was assembled into a Li||Li symmetric battery. The separator of the Li||Li symmetric battery was a PE separator, and the electrolyte was a commercial ester electrolyte. The battery was tested under the condition of current density of 1mA / cm 2 , deposition capacity of 1mAh / cm 2 . The polarization voltage of the lithium copper composite electrode was less than 100mV, and the voltage platform was symmetrical. It shows that the lithium copper composite electrode can effectively inhibit the growth of lithium dendrites, and exhibits excellent electrochemical stability.

[0088] Example 10

[0089] (1) The lithium slag was added to 1mol / L dilute hydrochloric acid and reacted for 24h. The reaction product was filtered, washed and dried for use;

[0090] (2) The metallic lithium was heated to 250℃ in a protective atmosphere to form a molten state;

[0091] (3) The reaction product in (1) was added to the molten lithium at a mass fraction of 25% and stirred for 30min to complete the reaction;

[0092] (4) The product obtained in (3) was uniformly coated on a tin-plated copper foil and cooled to room temperature to obtain a negative electrode sheet.

[0093] The negative electrode sheet was assembled into a Li||Li symmetric battery. The separator of the Li||Li symmetric battery was a PE separator, and the electrolyte was a commercial ester electrolyte. The battery was tested under the condition of current density of 1mA / cm 2, the deposition capacity is 5mAh / cm 2 The stable cycle is 600h, the polarization voltage is lower than 100mV, and the voltage platform is symmetrical. It shows that the lithium-copper composite electrode can effectively inhibit the growth of lithium dendrites and exhibit excellent electrochemical stability.

[0094] Example 11

[0095] (1) The lithium slag is added into 1mol / L dilute hydrochloric acid and reacted for 24h. The reaction product is filtered, washed and dried for standby;

[0096] (2) The metallic lithium is heated to 250℃ in a protective atmosphere to be in a molten state;

[0097] (3) The reaction product in (1) is added into the molten lithium with a mass fraction of 27.5% and stirred for 30min to make the reaction complete;

[0098] (4) The product obtained in (3) is uniformly coated on the tin-plated copper foil and cooled to room temperature to obtain a negative electrode sheet.

[0099] The negative electrode sheet is matched with a nickel-cobalt-manganese ternary positive electrode material to assemble a full battery. The separator of the full battery is a PE separator, and the electrolyte is a commercial ester electrolyte. After stable cycling for 250 cycles under the condition of 1C, there is still 80% capacity retention rate, which shows that the lithium-copper composite negative electrode can effectively inhibit the growth of lithium dendrites and exhibit excellent electrochemical stability.

[0100] Example 12

[0101] (1) The lithium slag is added into 1mol / L dilute hydrochloric acid and reacted for 24h. The reaction product is filtered, washed and dried for standby;

[0102] (2) The metallic lithium is heated to 250℃ in a protective atmosphere to be in a molten state;

[0103] (3) The reaction product in (1) is added into the molten lithium with a mass fraction of 30% and stirred for 30min to make the reaction complete;

[0104] (4) The product obtained in (3) is uniformly coated on the tin-plated copper foil and cooled to room temperature to obtain a negative electrode sheet.

[0105] The negative electrode sheet is matched with a lithium iron phosphate positive electrode material to assemble a full battery. The separator of the full battery is a PE separator, and the electrolyte is a commercial ester electrolyte. After stable cycling for 200 cycles under the condition of 2C, there is still 80% capacity retention rate, which shows that the lithium-copper composite negative electrode can effectively inhibit the growth of lithium dendrites and exhibit excellent electrochemical stability.

[0106] Example 13

[0107] (1) Lithium slag was added into 1 mol / L dilute hydrochloric acid and reacted for 24 h. The reaction product was filtered, washed, and dried for use;

[0108] (2) Metal lithium was heated to 250°C under a protective atmosphere to form a molten state;

[0109] (3) The reaction product in (1) was added into the molten lithium at a mass fraction of 15% and stirred for 30 min to complete the reaction;

[0110] (4) A piece of copper foil with a length of 15 cm and a width of 5 cm was cut and heated to 200°C on a heating table;

[0111] (5) The product obtained in (3) was uniformly coated onto the copper foil and cooled to room temperature to obtain a negative electrode sheet.

[0112] The negative electrode sheet was assembled into a Li||Li symmetric battery, and the separator of the Li||Li symmetric battery was a PE separator, and the electrolyte was a commercial ester-based electrolyte. The Li||Li symmetric battery was tested under the condition of a current density of 2 mA / cm 2 , and a deposition capacity of 1 mAh / cm 2 . After 200 h of stable cycling, the polarization voltage was lower than 150 mV, and the voltage platform was symmetrical. It was shown that the lithium-copper composite electrode could effectively inhibit the growth of lithium dendrites and exhibited excellent electrochemical stability.

[0113] Example 14

[0114] (1) Lithium slag was added into 1 mol / L dilute hydrochloric acid and reacted for 24 h. The reaction product was filtered, washed, and dried for use;

[0115] (2) Metal lithium was heated to 250°C under a protective atmosphere to form a molten state;

[0116] (3) The reaction product in (1) was added into the molten lithium at a mass fraction of 15% and stirred for 30 min to complete the reaction;

[0117] (4) Carbon paper was sequentially ultrasonically cleaned with alcohol and deionized water for 30 min and dried for use;

[0118] (5) The product obtained in (3) was uniformly coated onto the carbon paper and cooled to room temperature to obtain a negative electrode sheet.

[0119] The negative electrode sheet was assembled into a Li||Li symmetric battery, and the separator of the Li||Li symmetric battery was a PE separator, and the electrolyte was a commercial ester-based electrolyte. The Li||Li symmetric battery was tested under the condition of a current density of 2 mA / cm 2 , and a deposition capacity of 1 mAh / cm 2The lithium-copper composite electrode can effectively inhibit the growth of lithium dendrites and exhibits excellent electrochemical stability.

[0120] Example 15

[0121] (1) The lithium slag was added to 1 mol / L dilute hydrochloric acid and reacted for 24 h. The reaction product was filtered, washed and dried. The product was ball milled at a speed of 300 r / min for 3 h;

[0122] (2) The product in (1) was mixed and dispersed into NMP as a filler with PMMA, PAA at a ratio of 4:1:1 and stirred for 12 h;

[0123] (3) The slurry in (2) was scraped and coated on a copper foil and dried in a vacuum oven at 80°C for 24 h to obtain a modified copper foil.

[0124] The obtained modified copper foil was assembled into a Li||Cu battery with lithium metal. The separator of the Li||Cu battery was a PE separator, and the electrolyte was a commercial ester electrolyte. The Li||Cu battery was tested under the condition of a current density of 1 mA / cm 2 , and a deposition capacity of 1 mAh / cm 2 . The coulombic efficiency remained at about 96% after 150 cycles, indicating that the modified negative electrode current collector can effectively inhibit the growth of lithium dendrites and exhibits excellent electrochemical stability.

[0125] Example 16

[0126] (1) The lithium slag was added to 1 mol / L dilute hydrochloric acid and reacted for 24 h. The reaction product was filtered, washed and dried. The product was ball milled at a speed of 300 r / min for 3 h;

[0127] (2) The product in (1) was mixed and dispersed into NMP as a filler at a ratio of 10% with PEO, LiTFSI and stirred for 12 h at 60°C.

[0128] (3) The slurry in (2) was dropped into a polytetrafluoroethylene mold and left to dry for 24 h to obtain a PEO-based polymer solid-state electrolyte.

[0129] The prepared PEO-based polymer solid-state electrolyte was assembled into a Li|SPEs|Li lithium symmetric battery with a lithium metal negative electrode. The battery was tested under the condition of a current density of 0.1 mA / cm 2 , and a deposition capacity of 0.1 mAh / cm 2 . The polarization voltage was less than 50 mV and the voltage platform was symmetrical after 350 h of stable cycling. The lithium-copper composite electrode can effectively inhibit the growth of lithium dendrites and exhibits excellent electrochemical stability.

[0130] Comparative Example 1

[0131] Use 0.2mA / cm 2 A 6 mAh lithium anode was deposited on copper foil at a current density of 100 Å. This anode electrode was paired with a lithium iron phosphate cathode material to form a full battery. The separator used in the full battery was a PE membrane and the electrolyte was a commercial ester. Tested at 1C, the battery short-circuited after 100 cycles.

[0132] Comparative Example 2

[0133] A 50μm-thick thin lithium ion battery was used as the negative electrode. This negative electrode was paired with a lithium iron phosphate positive electrode material to form a full battery. The separator used in the full battery was a PE membrane, and the electrolyte was a commercial ester electrolyte. Tested at 2C, the battery short-circuited after 100 cycles.

Claims

1. A lithium-copper composite negative electrode prepared from lithium slag, characterized in that: The method comprises the following steps: (1) treating the lithium slag with a certain concentration of acid for a period of time, filtering and washing the product, and drying it in an oven; (2) heating and melting metallic lithium to obtain molten metallic lithium; (3) adding the product of (1) to the obtained molten lithium metal and stirring until the reaction is complete; (4) The molten metal lithium obtained in (3) is coated on the current collector and cooled to room temperature to obtain a negative electrode sheet.

2. The method for preparing a lithium-copper composite negative electrode prepared from lithium slag according to claim 1, characterized in that: The lithium slag used is sourced from one of spodumene (containing 5.8% to 8.1% Li2O), lepidolite (containing 3.2% to 6.45% Li2O), ferroalite (containing 7.1% to 10.1% Li2O), petalite (containing 2.9% to 4.8% Li2O) and ferroalite (containing 1.1% to 5% Li2O).

3. The method for preparing a lithium-copper composite negative electrode prepared from lithium slag according to claim 1, characterized in that: The lithium content of the lithium slag used is less than 0.3%.

4. The method for preparing a lithium-copper composite negative electrode prepared from lithium slag according to claim 1, characterized in that: The acid used in step (1) is one of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid.

5. The method for preparing a lithium-copper composite negative electrode prepared from lithium slag according to claim 1, characterized in that: The heating temperature of the metallic lithium in steps (2) and (3) is 180-260°C.

6. The method for preparing a lithium-copper composite negative electrode prepared from lithium slag according to claim 1, characterized in that: The stirring time in step (3) is 10-30 min.

7. The method for preparing a lithium-copper composite negative electrode prepared from lithium slag according to claim 1, characterized in that: The amount of the product added in step (3) accounts for 0%-30% of the total mass.

8. The method for preparing a lithium-copper composite negative electrode prepared from lithium slag according to claim 1, characterized in that: The heating and stirring processes are all completed under a protective gas atmosphere.

9. The method for preparing a lithium-copper composite negative electrode prepared from lithium slag according to claim 1, characterized in that: The lithium metal negative electrode current collector is copper foil, tinned copper foil, aluminum foil or carbonaceous flexible material.

10. According to claim 8, it is characterized in that: The protective atmosphere is helium, neon, nitrogen or argon atmosphere.

11. The use of a lithium-copper composite negative electrode prepared from lithium slag according to claim 1, characterized in that: The lithium metal battery is assembled into a lithium metal battery, which includes a positive electrode, a composite lithium metal negative electrode prepared from lithium slag, a separator and an electrolyte.

12. The lithium-copper composite negative electrode prepared from lithium slag according to claim 11 is used in assembling a lithium metal battery, characterized in that: The positive electrode material includes LiFePO4, LiCoO2, LiNi x Co y Mn 1-y O2,0≤x≤1,0≤y≤1、LiNi 0.5 Mn 1.5 O4; The diaphragm includes a glass fiber film, a polyethylene film, a polypropylene film, a polyethylene / polypropylene double-layer co-extruded film or a polypropylene / polyethylene / polypropylene three-layer co-extruded film; The electrolyte includes an ester electrolyte or an ether electrolyte.

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