Liquid alloy lithium ion battery electrode and method of making same

Abstract

The application relates to the field of lithium ion batteries, in particular to a liquid alloy lithium ion battery electrode and a preparation method thereof, which comprises the following steps: S1: mixing metal raw materials to generate an alloying reaction, then adding the formed liquid alloy into a first medium solvent, and performing ultrasonic crushing to obtain a liquid alloy suspension; S2: dissolving a lithium salt and a polymer in a second medium solvent to prepare solution A; S3: adding an electrode active material into the liquid alloy suspension to prepare solution B; S4: mixing solution A and solution B, coating the formed slurry on the surface of a current collector, and drying to obtain a battery electrode; wherein the liquid alloy is a Ga-In alloy or a Ga-In-M alloy, M is Bi or Sn; and the liquid alloy is in a liquid state at room temperature. Compared with the prior art, the application solves the problems of high porosity and low compaction density caused by the use of a carbon-based conductive agent in the prior art.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion batteries, specifically to a liquid alloy lithium-ion battery electrode and its preparation method. Background Technology

[0002] With the growing awareness of environmental protection and sustainable development, the new energy vehicle industry has experienced rapid growth, and the most crucial component of this industry is the power battery. Currently, the mainstream power batteries are lithium-ion batteries, and within lithium-ion batteries, the cathode material is paramount. The main cathode materials for lithium-ion batteries on the market are lithium cobalt oxide, lithium iron phosphate, and ternary materials. Among these, lithium iron phosphate and ternary materials are primarily used in power batteries.

[0003] Lithium iron phosphate (LFP) cathode materials are cheaper and safer, but their compaction density is significantly lower than that of ternary materials. Currently, mainstream LFP manufacturers achieve a compaction density of only 2.2-2.3 g / cc, resulting in a lower volumetric energy density, with a maximum of only 450 Wh / L. While optimizing material dimensions can achieve a compaction density of up to 2.8 g / cc, this is still far below the 3.5 g / cc compaction density commonly found in ternary materials, leading to a lower volumetric energy density in the battery.

[0004] The volumetric energy density of a battery is a crucial factor affecting its application. It is related to various components within the battery, such as the thickness and area of ​​the positive and negative electrodes and the separator. The thickness of the positive and negative electrode sheets is particularly important for volumetric energy density. Therefore, simply increasing the compaction density of material particles is insufficient to improve volumetric energy density; the composition of the electrode sheets also significantly impacts their compaction density. For example, using conductive carbon black additives with a large specific surface area greatly increases electrode porosity and reduces compaction density. Generally, electrode porosity can be simply calculated by the difference between the true density of the material and the electrode compaction density. The calculation equation is as follows: Electrode porosity (%) = (True density of mixture – Electrode compaction density) / True density of mixture × 100%. Under laboratory conditions, the porosity of ternary lithium-ion and lithium iron phosphate electrodes is generally between 35% and 40%.

[0005] Electrode components include conductive agents, polymers, and active materials. Currently, the conductive agents used commercially and in laboratories are mainly carbon-based, such as conductive carbon black, graphite, carbon nanotubes, and graphene. These materials have good conductivity and high specific surface area, but they have very low density, making them difficult to compact during electrode fabrication. This results in excessively high porosity in the electrode, thus limiting the volumetric energy density of lithium-ion batteries.

[0006] In summary, it is necessary to overcome the problems of high porosity and low compaction density caused by the use of carbon-based conductive agents, as mentioned above, in order to further improve the volumetric energy density of lithium-ion batteries. Summary of the Invention

[0007] The purpose of this invention is to provide a liquid alloy lithium-ion battery electrode and its preparation method to solve at least one of the above-mentioned problems, thereby addressing the issues of high porosity and low compaction density caused by the use of carbon-based conductive agents in the prior art, and improving the volumetric energy density of lithium-ion batteries.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] The first aspect of this invention discloses a method for preparing a liquid alloy lithium-ion battery electrode, comprising the following steps:

[0010] S1: Mix metal raw materials to undergo an alloying reaction, then add the formed liquid alloy to the first medium solvent and ultrasonically break it to obtain a liquid alloy suspension;

[0011] S2: Dissolve the lithium salt and polymer in a second medium solvent to prepare solution A;

[0012] S3: Add the electrode active material to the liquid alloy suspension obtained in step S1 to prepare solution B;

[0013] S4: Mix solution A obtained in step S2 with solution B obtained in step S3, and coat the slurry formed on the surface of the current collector. After drying, the battery electrode is obtained.

[0014] The liquid alloy is a Ga-In alloy or a Ga-In-M alloy, where M can be, but is not limited to, Bi or Sn; the liquid alloy is liquid at room temperature.

[0015] Metals, as conductive agents, have a low specific surface area, allowing for smaller porosity in electrodes compared to conductive carbon black, thus increasing the electrode's compaction density. Under laboratory conditions, the porosity of lithium iron phosphate electrodes can be reduced from 40% to approximately 25%, thereby increasing the battery's volumetric energy density. This increased the volumetric energy density of lithium iron phosphate batteries from 405Wh / L to 465Wh / L (the calculation model is a pouch cell with a separator thickness of 12 micrometers, a graphite thickness of 30 micrometers, a positive electrode capacity of 1.6mAh, and an operating voltage of 3.5V). Generally, industrially produced electrodes, due to superior manufacturing processes, have higher compaction densities than laboratory-coated electrodes.

[0016] As a conductive additive, the liquid alloy has good fluidity, is evenly dispersed, and has a higher thermal conductivity, which is beneficial to heat conduction during the battery cycle and can dissipate heat faster. In addition, the liquid alloy itself can also act as a polymer. On the other hand, although the liquid alloy can greatly reduce the porosity, the reduction of porosity will affect the ionic conductivity of the electrode sheet, making the transmission of lithium ions more difficult. Therefore, a lithium polymer needs to be added to the electrode to improve the lithium conduction performance of the electrode.

[0017] Preferably, when the liquid alloy is a Ga-In alloy, the mass ratio of Ga to In is 4:1; when the liquid alloy is a Ga-In-M alloy, the mass ratio of Ga, In to M is 3:1:x, where 0 < x < 3; the melting point of the liquid alloy is lower than 25°C.

[0018] Preferably, the temperature of the alloying reaction is 55 - 100°C and the time is 10 - 30 min; the ultrasonic crushing power is 600 - 700 W, and the time is controlled at about 2 h until the liquid alloy is fully suspended in the first medium solvent.

[0019] Preferably, the first medium solvent can be, but is not limited to, solvents such as N-methylpyrrolidone (NMP) or tetrahydrofuran (THF) that can dissolve both the lithium salt and the polymer simultaneously; the mass ratio of the liquid alloy to the first medium solvent is 1:4.3.

[0020] Preferably, the lithium salt can be, but is not limited to, LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiFSI (lithium bis(fluorosulfonyl)imide) or LiPF6 (lithium hexafluorophosphate); the polymer can be, but is not limited to, PVDF-HFP (poly(vinylidene fluoride - hexafluoropropylene)), PVDF (poly(vinylidene fluoride)), PEO (poly(ethylene oxide)) or Aquivion SO3Li ( dispersion, lithium salt form); the second medium solvent can be, but is not limited to, solvents such as N-methylpyrrolidone (NMP) or tetrahydrofuran (THF) that can dissolve both the lithium salt and the polymer simultaneously; the mass ratio of the lithium salt, the polymer to the second medium solvent is 3:2:20.

[0021] Preferably, the electrode active material is a positive electrode active material or a negative electrode active material; the positive electrode active material can be, but is not limited to, LFP (LiFePO4), LCO (LiCoO2) or the ternary material NCM (N, C, M are Ni, Co, Mn respectively); the negative electrode active material can be, but is not limited to, graphite or silicon carbon; the mass ratio of the electrode active material to the liquid alloy in the liquid alloy suspension is 18:1.

[0022] Preferably, solution B and solution A are mixed according to the mass ratio of the electrode active material to the lithium salt of 30:1.

[0023] Preferably, the current collector may be, but is not limited to, aluminum foil, carbon-coated aluminum foil, copper foil, carbon-coated copper foil, or stainless steel foil.

[0024] Preferably, the thickness of the slurry coated on the surface of the current collector is 100-200 μm.

[0025] The second aspect of the present invention discloses a liquid alloy lithium-ion battery electrode, which is prepared by any of the methods described above.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] This method primarily focuses on the electrode composition, aiming to minimize the porosity of the electrodes to improve the volumetric energy density of the battery. Currently, one of the factors hindering electric vehicles is their driving range; increasing energy density helps extend this range. Furthermore, high volumetric energy density opens up applications in 3C electronics, allowing for further reductions in the size of batteries in devices such as mobile phones and computers.

[0028] Liquid alloys can not only improve the volumetric energy density and reduce porosity of lithium iron phosphate cathodes, but also further optimize the volumetric energy density of ternary materials, continuing to expand the advantages of ternary materials in terms of energy density. Simultaneously, liquid alloys can also be combined with lithium cobalt oxide for use in 3C products, reducing battery size. For silicon-carbon and graphite anodes, similar to the cathodes, replacing the currently mainstream carbon-based conductive agents with liquid metal conductive agents will also improve the volumetric energy density and reduce porosity of the anode.

[0029] The electrode sheets prepared by this method have low porosity, high volumetric energy density, good electrical and thermal conductivity, and significantly improved capacity. Attached Figure Description

[0030] Figure 1 The binary phase diagram of Ga-In;

[0031] Figure 2 The CV curve of the half-cell of Example 1;

[0032] Figure 3 The CV curve is shown for the half-cell of Comparative Example 1.

[0033] Figure 4 The graph shows the capacity change of the half-cells of Example 1 and Comparative Example 1 over 100 cycles.

[0034] Figure 5 The graph shows the capacity change of the half-cells of Example 2 and Comparative Example 2 after 100 cycles.

[0035] Figure 6The graph shows the capacity change of the half-cells of Example 3 and Comparative Example 3 after 100 cycles.

[0036] Figure 7 The graph shows the capacity change of the half-cells of Example 4 and Comparative Example 4 after 100 cycles.

[0037] Figure 8 This is a schematic diagram of the preparation process of the present invention;

[0038] Figure 9 This is a schematic comparison of the microstructures of the liquid alloy electrode sheet prepared by this invention and the carbon-based conductive agent electrode sheet. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0040] Unless otherwise specified, the reagents used in the following description may be commonly used reagents or commercially available reagents in the art, and the methods used may be conventional means or methods in the art.

[0041] In simple terms, the steps of this method include:

[0042] a. Mix low-melting-point metals and heat them to produce an alloying reaction, forming a liquid alloy.

[0043] b. Add the liquid alloy to the medium solvent, and use an ultrasonic cell disruptor to sonicate the alloy suspension to refine the alloy particles.

[0044] c. Take out the alloy suspension after refining the metal particles, add lithium salt, polymer and electrode active material respectively, and mix and stir to prepare slurry.

[0045] d. Apply the stirred slurry onto the current collector, and then put it into an oven to dry (if secondary drying is required, proceed to step e; if secondary drying is not required, proceed to step f).

[0046] e. Remove the dried electrodes and place them in a vacuum oven for a second drying.

[0047] f. Remove the completely dried electrodes, roll and slice them in a dry environment, and then assemble the battery in an inert gas glove box.

[0048] Preferably, the liquid alloy is composed primarily of Ga metal, with the remaining doped metals selected from one or more low-melting-point metals such as Bi, In, and Sn. Taking In doping as an example, with a Ga:In ratio of 4:1 (mass ratio), the resulting liquid alloy has a melting point close to the lowest possible value, around 15.3℃ (see Ga-In binary phase diagram). Figure 1) The ratio of Ga to In should not deviate too much from this ratio, otherwise the liquid alloy will solidify or be in a semi-liquid-solid state at room temperature. Therefore, the metal ratio selected according to the phase diagram should meet the requirement of being in a liquid state at room temperature.

[0049] Preferably, the medium solvent for dispersing alloy particles is N-methylpyrrolidone or tetrahydrofuran, etc., which can dissolve polymers and lithium salts, and at the same time has low viscosity, good thermal stability and good chemical stability.

[0050] Preferably, the lithium salt used is lithium salts such as LiTFSI or LiFSI, LiPF6 (not limited to these three mentioned). For lithium salts with strong water absorption, secondary vacuum drying is required to remove the remaining moisture. At the same time, after secondary drying, the electrode sheet needs to be operated in a dry environment throughout the process to avoid the electrode sheet absorbing too much moisture as much as possible.

[0051] Using an ultrasonic cell disruptor for ultrasonic treatment, large chunks of liquid alloy can be cut into micro-nano scale small particles. When taking the alloy suspension, according to needs, the alloy can be made to be as evenly distributed in the liquid as possible by magnetic stirrer rotation or other methods.

[0052] Taking the Ga-In-M liquid alloy as an example, the specific operation steps are as follows, and reference can be made to Figure 8 :

[0053] (1) Synthesizing Ga-In-M liquid alloy particles includes:

[0054] 1. Take appropriate amounts of Ga, In and metals such as Bi, Sn, etc. according to the mass ratio of Ga:In:M of 3:1:x (0 < x < 3) and mix them.

[0055] 2. Heat the Ga-In-M alloy at about 55 - 100 °C for 10 - 30 min, and stir during the heating process to make the alloy mix evenly.

[0056] 3. Mix the Ga-In-M alloy with N-methylpyrrolidone (NMP) or tetrahydrofuran (THF) at a mass ratio of 1:4.3, and use an ultrasonic cell disruptor to ultrasonically treat the mixture at a power of 600 - 700 W for a total of 2 hours, with each ultrasonic treatment for 30 s and a pause of 2 min. After sufficient stirring, a mixture of finer Ga-In-M liquid alloy particles and NMP (or THF) can be obtained.

[0057] (2) Preparing a lithium iron phosphate (or ternary material NCM or lithium cobalt oxide) positive electrode and a graphite (or silicon-carbon) negative electrode: <{

[0058] 1. First, prepare a solution according to the mass ratio of LiTFSI:PVDF-HFP:NMP (or THF) = 0.3:0.2:4.0.

[0059] 2. Mix the electrode active material (lithium iron phosphate or ternary material NCM, or lithium cobalt oxide, or graphite, or silicon carbide) with liquid alloy (Ga-In-M) in a ratio of 18:1 (mass ratio), and stir the electrode active material and Ga-In-M alloy suspension using a pulper at a speed of 600 r / min for 10-20 min.

[0060] 3. After stirring, add LiTFSI and PVDF-HFP solution in a dry environment at a ratio of LFP:LiTFSI = 30:1, and then stir with a pulper at a speed of 2000 r / min for 10-20 min.

[0061] 4. After the slurry is fully mixed, use a coating machine to coat it onto the surface of carbon-coated aluminum foil (copper foil for the negative electrode) at a thickness of 100-200 micrometers.

[0062] The coated electrode sheet is placed in an oven and kept at 80°C for more than 6 hours, and then vacuum dried at 80°C for more than 6 hours to obtain an electrode active material (lithium iron phosphate or ternary material NCM, or lithium cobalt oxide, or graphite, or silicon carbide) electrode sheet.

[0063] 5. In a dry environment (such as a drying room or glove box), the electrode sheets are compacted and sliced ​​using a roller press, and the battery is assembled.

[0064] Example 1

[0065] A method for preparing a liquid metal lithium-ion battery cathode is as follows:

[0066] Mix 0.40g Ga and 0.10g In metal, and heat the Ga-In alloy at approximately 55℃ for 30 minutes, stirring with a stainless steel rod during heating to ensure uniform mixing. Then add 2.15g N-methylpyrrolidone (NMP) and mix with the prepared liquid alloy. Use an ultrasonic cell disruptor at 650W to sonicate the mixture multiple times for a total of 2 hours, sonicating for 30 seconds each time, pausing for 2 minutes to prevent overheating. Observe the size of the metal particles in the NMP during sonication to obtain fine Ga-In liquid alloy particles.

[0067] Prepare a solution by mixing 0.30g LiTFSI, 0.20g PVDF-HFP, and 4.00g NMP. Take 0.40g LFP and 0.12g Ga-In alloy suspension and stir using a pulping machine at 600 rpm for approximately 15 minutes. After stirring, add 0.20g of the LiTFSI and PVDF-HFP mixture to a dry environment, and then stir using a pulping machine at 2000 rpm for 15 minutes. After thorough stirring, coat the slurry onto the surface of carbon-coated aluminum foil with a thickness of 150 micrometers using a coating machine. Place the coated electrode in an oven and keep it at 80℃ for 8 hours, then vacuum dry it in a vacuum oven at 80℃ for 8 hours to obtain the LFP electrode.

[0068] After the electrode sheets were prepared, they were cut into 12mm diameter sheets and assembled into coin cells to test the relevant electrochemical performance.

[0069] Example 2

[0070] A method for preparing a liquid metal lithium-ion battery cathode is as follows:

[0071] Mix 0.40g of Ga metal, 0.10g of In metal, and 0.10g of Bi metal. Heat the Ga-In-Bi alloy at approximately 80℃ for 30 minutes, stirring with a stainless steel rod during heating to ensure uniform mixing. Then add 2.15g of N-methylpyrrolidone (NMP) and mix with the prepared liquid alloy. Use an ultrasonic cell disruptor at 650W to sonicate the mixture multiple times for a total of 2 hours, sonicating for 30 seconds each time, pausing for 2 minutes to prevent overheating. Observe the size of the metal particles in the NMP during sonication to obtain fine Ga-In-Bi liquid alloy particles.

[0072] Prepare a solution by mixing 0.30g LiTFSI, 0.20g PVDF-HFP, and 4.00g NMP. Take 0.40g LFP and 0.12g Ga-In-Bi alloy suspension and stir using a pulping machine at 600 rpm for approximately 15 minutes. After stirring, add 0.20g of the LiTFSI and PVDF-HFP mixture to a dry environment, and then stir using a pulping machine at 2000 rpm for 15 minutes. After thorough stirring, coat the slurry onto the surface of carbon-coated aluminum foil with a thickness of 150 micrometers using a coating machine. Place the coated electrode in an oven and keep it at 80℃ for 8 hours, then vacuum dry it in a vacuum oven at 80℃ for 8 hours to obtain the LFP electrode.

[0073] After the electrode sheets were prepared, they were cut into 12mm diameter sheets and assembled into coin cells to test the relevant electrochemical performance.

[0074] Example 3

[0075] A method for preparing a liquid metal lithium-ion battery cathode is as follows:

[0076] Mix 0.40g of Ga metal and 0.10g of In metal, and heat the Ga-In alloy at approximately 55℃ for 30 minutes, stirring with a stainless steel rod during heating to ensure uniform mixing. Then add 2.15g of N-methylpyrrolidone (NMP) and mix with the prepared liquid alloy. Use an ultrasonic cell disruptor at 650W to sonicate the mixture multiple times for a total of 2 hours, sonicating for 30 seconds each time, pausing for 2 minutes to prevent overheating. Observe the size of the metal particles in the NMP during sonication to obtain fine Ga-In liquid alloy particles.

[0077] Prepare a solution by mixing 0.30g LiTFSI, 0.20g PVDF-HFP, and 4.00g NMP. Take 0.40g LCO and 0.12g Ga-In alloy suspension and stir using a pulping machine at 600 rpm for approximately 15 minutes. After stirring, add 0.20g of the LiTFSI and PVDF-HFP mixture to a dry environment, and then stir using a pulping machine at 2000 rpm for 15 minutes. After thorough stirring, coat the slurry onto the surface of carbon-coated aluminum foil with a thickness of 150 micrometers using a coating machine. Place the coated electrode in an oven and keep it at 80℃ for 8 hours, then vacuum dry it in a vacuum oven at 80℃ for 8 hours to obtain the LCO electrode.

[0078] After the electrode sheets were prepared, they were cut into 12mm diameter sheets and assembled into coin cells to test the relevant electrochemical performance.

[0079] Example 4

[0080] A method for preparing a liquid metal lithium-ion battery anode is as follows:

[0081] Mix 0.40g of Ga metal and 0.10g of In metal, and heat the Ga-In alloy at approximately 55℃ for 30 minutes, stirring with a stainless steel rod during heating to ensure uniform mixing. Then add 2.15g of N-methylpyrrolidone (NMP) and mix with the prepared liquid alloy. Use an ultrasonic cell disruptor at 650W to sonicate the mixture multiple times for a total of 2 hours, sonicating for 30 seconds each time, pausing for 2 minutes to prevent overheating. Observe the size of the metal particles in the NMP during sonication to obtain fine Ga-In liquid alloy particles.

[0082] Prepare a solution by mixing 0.30g LiTFSI, 0.20g PVDF-HFP, and 4.00g NMP. Take 0.40g graphite and 0.12g Ga-In alloy suspension, and stir using a pulping machine at 600 rpm for approximately 15 minutes. After stirring, add 0.20g of the LiTFSI and PVDF-HFP mixture to a dry environment, and then stir using a pulping machine at 2000 rpm for 15 minutes. After thorough stirring, coat the slurry onto a carbon-coated copper foil surface to a thickness of 150 micrometers using a coating machine. Place the coated electrode in an oven and heat at 80℃ for 8 hours, then vacuum dry at 80℃ for 8 hours to obtain the graphite electrode.

[0083] After the electrode sheets were prepared, they were cut into 12mm diameter sheets and assembled into coin cells to test the relevant electrochemical performance.

[0084] Comparative Example 1

[0085] Take 0.40g of LFP and 0.022g of conductive carbon black, and stir them in a pulping machine at 600r / min for about 15min. After stirring, add 0.840g of PVDF-HFP solution (solvent: NMP) with a concentration of 2.62wt% (the same below), and then stir in a pulping machine at 2000r / min for 15min. After the slurry is fully stirred, coat it with a coating machine to a thickness of 300 micrometers on the surface of carbon-coated aluminum foil (ensuring the electrode loading, i.e., the mass of active material in the electrode is consistent with that in Example 1). Place the coated electrode in an oven and keep it at 80℃ for 8 hours, and then vacuum dry it in a vacuum oven at 80℃ for 8 hours to obtain the LFP electrode.

[0086] After the electrode sheets were prepared, they were cut into 12mm diameter sheets and assembled into coin cells to test the relevant electrochemical performance.

[0087] Comparative Example 2

[0088] Take 0.40g of LFP and 0.022g of conductive carbon black, and stir them in a pulping machine at 600 rpm for about 15 minutes. After stirring, add a 2.62% PVDF-HFP solution (solvent: NMP), and then stir in a pulping machine at 2000 rpm for 15 minutes. After the slurry is fully stirred, coat it with a coating machine to a thickness of 300 micrometers on the surface of carbon-coated aluminum foil (ensuring the electrode loading, i.e., the mass of active material in the electrode is consistent with that in Example 2). Place the coated electrode in an oven and keep it at 80°C for 8 hours, and then vacuum dry it in a vacuum oven at 80°C for 8 hours to obtain the LFP electrode.

[0089] After the electrode sheets were prepared, they were cut into 12mm diameter sheets and assembled into coin cells to test the relevant electrochemical performance.

[0090] Comparative Example 3

[0091] Take 0.40g LCO and 0.022g conductive carbon black, and stir them in a pulping machine at 600r / min for about 15min. After stirring, add a 2.62% PVDF-HFP solution (also NMP solvent), and then stir in a pulping machine at 2000r / min for 15min. After the slurry is fully stirred, coat it with a coating machine to a thickness of 150 micrometers on the surface of carbon-coated aluminum foil (ensuring the electrode loading, i.e., the electrode active material mass is consistent with that in Example 3). Place the coated electrode in an oven and keep it at 80℃ for 8 hours, and then vacuum dry it in a vacuum oven at 80℃ for 8 hours to obtain the LCO electrode.

[0092] After the electrode sheets were prepared, they were cut into 12mm diameter sheets and assembled into coin cells to test the relevant electrochemical performance.

[0093] Comparative Example 4

[0094] Take 0.40g of graphite and 0.022g of conductive carbon black, and stir them in a pulping machine at 600r / min for about 15min. After stirring, add a 2.62% PVDF-HFP solution (also NMP solvent), and then stir in a pulping machine at 2000r / min for 15min. After the slurry is fully stirred, coat it with a 150-micron thickness onto the surface of the carbon-coated copper foil using a coating machine (ensuring the electrode loading, i.e., the mass of active material in the electrode is consistent with that in Example 4). Place the coated electrode in an oven and keep it at 80°C for 8 hours, and then vacuum dry it in a vacuum oven at 80°C for 8 hours to obtain the graphite electrode.

[0095] After the electrode sheets were prepared, they were cut into 12mm diameter sheets and assembled into coin cells to test the relevant electrochemical performance.

[0096] Comparative analysis of the examples and comparative examples:

[0097] First, let's look at the CV curves of Example 1 and Comparative Example 1 ( Figure 2 and Figure 3 As can be seen, the addition of liquid metal did not produce any new side reactions, thus not affecting battery performance. Furthermore, the capacity decay curves of various embodiments and comparative examples (…) Figures 4-7 As can be seen from the data, for most positive and negative electrode materials, using liquid metal as a conductive agent to replace conductive carbon has little or no impact on the electrode's capacity and attenuation; the capacities and voltages of the two are similar. Therefore, the smaller liquid metal electrode has a higher overall volumetric energy density.

[0098] In addition Figure 9 As can be seen, the electrode on the left side of the figure (the liquid alloy electrode proposed in this invention) can effectively reduce its volume while maintaining the same active structure as the electrode on the right side (the traditional carbon-based conductive agent electrode), thus effectively improving the volumetric energy density.

[0099] Example 5

[0100] This embodiment is basically the same as Embodiment 1, except that LiFSI is used as the lithium salt. The performance of the material prepared in this embodiment is similar to that in Embodiment 1.

[0101] Example 6

[0102] This embodiment is basically the same as Example 1, except that PEO is used as the polymer. The properties of the material prepared in this embodiment are similar to those in Example 1.

[0103] Example 7

[0104] This embodiment is basically the same as Embodiment 1, except that both the first medium solvent and the second medium solvent are THF. The properties of the material prepared in this embodiment are similar to those in Embodiment 1.

[0105] Example 8

[0106] This embodiment is basically the same as embodiment 2, except that the titanium alloy is Ga-In-Sn. The properties of the material obtained in this embodiment are similar to those in embodiment 2.

[0107] Example 9

[0108] This embodiment is basically the same as embodiment 3, except that LiPF6 is used as the lithium salt. The properties of the material prepared in this embodiment are similar to those in embodiment 3.

[0109] Example 10

[0110] This embodiment is basically the same as Example 4, except that the polymer used is Aquivion SO3Li. The properties of the material prepared in this embodiment are similar to those in Example 4.

[0111] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a liquid alloy lithium-ion battery electrode, characterized in that, It includes the following steps: S1: Mix metal raw materials to carry out an alloying reaction, and then add the formed liquid alloy into a first medium solvent, and perform ultrasonic crushing to obtain a liquid alloy suspension; S2: Dissolve a lithium salt and a polymer in a second medium solvent to prepare solution A; wherein, the polymer is PVDF-HFP, PVDF, PEO or Aquivion SO3Li; S3: Add electrode active material into the liquid alloy suspension obtained in step S1 to prepare solution B; S4: Mix solution A obtained in step S2 and solution B obtained in step S3, coat the formed slurry on the surface of a current collector, and complete drying to obtain a battery electrode; Wherein, the liquid alloy is a Ga-In alloy or a Ga-In-M alloy, and M is Bi or Sn; the liquid alloy is liquid at room temperature.

2. The method for preparing a liquid alloy lithium-ion battery electrode according to claim 1, characterized in that, When the liquid alloy is a Ga-In alloy, the mass ratio of Ga to In is 4:1; when the liquid alloy is a Ga-In-M alloy, the mass ratio of Ga, In to M is 3:1:x, 0 < x < 3; the melting point of the liquid alloy is lower than 25°C.

3. The method for preparing a liquid alloy lithium-ion battery electrode according to claim 1, characterized in that, The temperature of the alloying reaction is 55-100°C, and the time is 10-30 min; the ultrasonic crushing is carried out using a cell ultrasonic crusher at a power of 600-700 W.

4. The method for preparing a liquid alloy lithium-ion battery electrode according to claim 1, characterized in that, The first medium solvent is N-methylpyrrolidone or tetrahydrofuran; the mass ratio of the liquid alloy to the first medium solvent is 1:4.

3.

5. The method for preparing a liquid alloy lithium-ion battery electrode according to claim 1, characterized in that, The lithium salt is LiTFSI, LiFSI or LiPF6; the second medium solvent is N-methylpyrrolidone or tetrahydrofuran; the mass ratio of the lithium salt, the polymer to the second medium solvent is 3:2:

20.

6. The method for preparing a liquid alloy lithium-ion battery electrode according to claim 1, characterized in that, The electrode active material is a positive electrode active material or a negative electrode active material; the positive electrode active material includes LFP, LiCoO2 or ternary material NCM; the negative electrode active material includes graphite or silicon-carbon; the mass ratio of the electrode active material to the liquid alloy in the liquid alloy suspension is 18:

1.

7. The method for preparing a liquid alloy lithium-ion battery electrode according to claim 1, characterized in that, Solution B and solution A are mixed according to the mass ratio of the electrode active material to the lithium salt of 30:

1.

8. The method for preparing a liquid alloy lithium-ion battery electrode according to claim 1, characterized in that, The current collector is carbon-coated aluminum foil, carbon-coated copper foil or stainless steel foil.

9. The method for preparing a liquid alloy lithium-ion battery electrode according to claim 1, characterized in that, The thickness of the slurry coated on the surface of the current collector is 100-200 μm.

10. A liquid alloy lithium-ion battery electrode, characterized in that, Prepared by the method according to any one of claims 1-9.

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