Metal gel current collector and preparation method and application thereof

Abstract

The invention discloses a metal gel current collector and a preparation method and application thereof, and belongs to the technical field of electrode materials. The metal gel current collector provided by the invention comprises a three-dimensional gel network and a liquid metal compound dispersed in the three-dimensional gel network, the three-dimensional gel network has ionic conductivity; the liquid metal compound takes liquid metal as a continuous phase, and the liquid metal is coated with a mixture of a conductive active core; the mass of the liquid metal compound accounts for 90-95% of the mass of the metal gel current collector; the mass ratio of the liquid metal to the conductive active core is 100: (3-80). By using the metal gel current collector provided by the invention, sufficient electrode / electrolyte interface contact sites can be provided, and a reaction interface is increased; direct contact between an electrolyte and an electrode can be blocked, and parasitic reaction and dendritic crystal formation are effectively inhibited; and synergic consideration of high reaction kinetics and long cycle stability is realized.

Description

Technical Field

[0001] This invention belongs to the field of electrode material technology, and more specifically, relates to a metal gel current collector, its preparation method and application. Background Technology

[0002] The electrochemical behavior of metal anodes plays a crucial role in the energy conversion efficiency, achievable energy density, and cycle performance of metal-based rechargeable batteries. With the large-scale application of renewable energy and the upgrading of the electric vehicle industry, higher requirements are being placed on the energy density, charge / discharge rate, safety, and cycle life of batteries.

[0003] An ideal metal anode requires both rapid and reversible metal deposition / stripping to ensure high-rate performance and long-term cycling stability. However, these two objectives constitute a fundamental challenge due to the inherent reaction mechanism of metal surface deposition / stripping, specifically manifested as follows: The charging and discharging processes of metal anodes both rely on the deposition (charging) and stripping (discharging) of metal ions on the electrode surface. To achieve rapid charging and discharging and accelerate the reaction kinetics, it is necessary to increase the contact area at the electrode / electrolyte interface and reduce the charge transfer resistance to achieve rapid charge transfer. However, increasing the contact area between the metal and the electrolyte will cause two major problems that seriously compromise cycle stability: Side reactions are exacerbated: For example, lithium metal readily reacts with carbonate electrolytes (such as EC / DMC) to form an unstable solid electrolyte interface (SEI). Repeated breakup and reconstruction of the SEI consumes electrolyte and lithium, leading to the loss of active materials; zinc metal reacts with H in aqueous electrolytes. + H2O undergoes the hydrogen evolution reaction (HER) and forms soluble zincates (such as Zn(OH)4²). - This also leads to electrolyte consumption and electrode structure deterioration. Uncontrolled dendrite growth: During metal deposition, an uneven electric field is easily formed in the electrolyte wetting area, causing lithium / zinc to grow into sharp dendrites disorderly along the high electric field region. Lithium dendrites have high hardness and can easily pierce the separator, causing battery short circuits. Although zinc dendrites have high toughness, they can also lead to a decrease in metal utilization and accelerated cycle decay. It is evident that there is an irreconcilable trade-off between "expanding the interface to accelerate kinetics" and "reducing contact to ensure stability": simply expanding the interface will exacerbate side reactions and dendrite growth; excessively restricting the contact between the metal and the electrolyte will hinder charge transfer and significantly reduce rate performance. Existing technologies have conducted considerable research to address the common challenges of metallic anodes, for example: (1) Modification of porous current collector: In order to balance the expansion of the interface and the reduction of local current density, porous graphene is used in lithium metal batteries and porous zinc foil is used as current collector in zinc-ion batteries. Although it can improve rate performance and reduce polarization, the increased surface area brought about by the porous structure will inevitably provide additional sites for the formation of side reactions and passivation layers, making it difficult to avoid the problems of uneven metal deposition and dendrite formation.

[0004] (2) Dense coating modification: The metal is isolated from the electrolyte by coating with an insulating / semi-insulating coating, such as coating the lithium metal surface with Li3N and the zinc surface with Al2O3. Although such coatings can suppress side reactions, they will significantly increase the charge transfer resistance and cannot meet the requirements of fast charging. (3) Interfacial chemical coordination regulation: Unlike physical structure adjustment or blocking, cutting-edge research utilizes molecular coordination mechanisms to construct "ion sieve" type interfaces. For example, biomass or specific chelating layers are used to actively reshape the interfacial ion solvation structure, thereby reducing the desolvation energy barrier and meeting the needs of suppressing side reactions and accelerating kinetics. However, even the most advanced zinc anodes currently available exhibit limited lifetimes (≤1200 hours when utilization is ≥60%, see reference: Wu H, Yin H, Liu R, et al. Chelation Effect Induced Robust Biomass Protective Layer for Aqueous Zn Metal Anode [J]. Advanced Energy Materials, 2025, 15: 2501359) and high overpotentials (50 mA·cm). -2 ≥480 mV, Reference: Ou Z, Li X, Wang Y, et al. Zn 2+ -Rich ChelateLayer Facilitates Ultrahigh-Rate Zinc Anodes [J]. Advanced Energy Materials, 2025, 15: 2404-203.). It is difficult to meet long-term cycle stability requirements.

[0005] In summary, the trade-off between "high reaction kinetics and long cycle stability" faced by metal anodes is common, and existing technologies cannot overcome this contradiction. Therefore, developing a new type of current collector to fundamentally resolve the inherent conflict between "expanding the interface to accelerate kinetics" and "reducing contact to suppress side reactions / dendritic formations" and achieve a synergistic improvement in the high-rate performance and long-cycle stability of metal anodes has become a key technological requirement for promoting the industrialization of next-generation batteries. Summary of the Invention

[0006] 1. The problem to be solved To address the technical challenge of balancing high reaction kinetics and long-cycle stability in existing metal anodes during charge and discharge, this invention provides a metal gel current collector, its preparation method, an electrode containing this metal gel current collector, and a battery.

[0007] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a metal gel current collector, comprising a three-dimensional gel network and a liquid metal composite dispersed in the three-dimensional gel network; The three-dimensional gel network has ionic conductivity; The liquid metal composite is a mixture in which liquid metal is the continuous phase and the liquid metal is coated with a conductive active core. The conductive active core comprises particles of one or more of zinc, copper, nickel, and silicon. The mass of the liquid metal composite accounts for 90-95% of the mass of the metal gel current collector; The mass ratio of the liquid metal to the conductive active core is 100:(3~80).

[0008] It should be noted that the metal gel current collector consists of a conductive active core, liquid metal, and a three-dimensional gel network from the inside out. Because the liquid metal is a continuous phase, and the conductive active core is encapsulated within it, an electronic conduction pathway can be formed. Due to the ionic conductivity of the three-dimensional gel network, the conductive active core can guide ions from the electrolyte to deposit onto it. Furthermore, when ions in the deposition path come into contact with the liquid metal, they can form elemental metal and be encapsulated within the liquid metal, thus forming an ion pathway. Taking a zinc battery as an example, during deposition (charging), the conductive active core guides newly reduced zinc ions to diffuse inward, passing through the three-dimensional gel network and precipitating on and around the surface of the conductive active core embedded in the liquid metal. During stripping (discharging), zinc ions are extracted from the interior of the metal gel current collector. This inward zinc deposition / stripping mechanism effectively suppresses parasitic reactions and dendrite formation by preventing direct contact between the electrolyte and the zinc electrode.

[0009] As a preferred embodiment of any technical solution in the first aspect of the present invention, the liquid metal includes one or more of gallium (Ga) metal, gallium-indium (Ga-In) alloy, and gallium-indium-tin (Ga-In-Sn) alloy.

[0010] As a preferred embodiment of any technical solution in the first aspect of the present invention, the three-dimensional gel network is formed by cross-linking one or more of the following: sodium alginate, polyvinyl alcohol, polyethylene oxide, waterborne polyurethane, thermoplastic polyurethane, polyvinylidene fluoride-hexafluoropropylene copolymer, and ethylene-vinyl acetate copolymer.

[0011] Further preferably, the three-dimensional gel network is formed by cross-linking one or more of cross-linked sodium alginate, polyvinyl alcohol, polyethylene oxide, and waterborne polyurethane.

[0012] A second aspect of the present invention provides a method for preparing a metal gel current collector, comprising the following steps: (1) The conductive active core and liquid metal are dispersed in an acid solution or an alkaline solution, separated and washed to obtain a liquid metal composite; wherein the conductive active core includes one or more particles of zinc, copper, nickel and silicon; (2) The liquid metal composite is mixed with the polymer solution for 10-30 min and dried to form a film to obtain a metal gel current collector; Wherein, the mass ratio of the liquid metal to the conductive active core in step (1) is 100:(3~80); and / or, In step (2), the mass ratio of the liquid metal composite to the polymer is (18~95):1.

[0013] As a preferred embodiment of any technical solution in the second aspect of the present invention, in step (1), the liquid metal includes one or more of gallium metal, gallium-indium alloy, and gallium-indium-tin alloy.

[0014] As a preferred embodiment of any technical solution in the second aspect of the present invention, in step (1), the acid solution is a strong acid solution with a hydrogen ion concentration of 0.1~1 mol / L.

[0015] As a preferred embodiment of any technical solution in the second aspect of the present invention, in step (1), the alkaline solution is a strong alkaline solution with a hydroxide ion concentration of 0.1~1 mol / L.

[0016] It should be noted that the acid or alkali solution can dissolve a small amount of liquid metal to allow the conductive active core to enter the liquid metal, forming a structure in which the liquid metal coats the conductive active core. If the concentration of the acid or alkali solution is too low, it will not be conducive to the entry of the conductive active core. If the concentration is too high, it will over-dissolve the liquid metal, causing the liquid metal to be lost too quickly and unable to completely coat the conductive active core.

[0017] As a preferred embodiment of any technical solution in the second aspect of the present invention, in step (1), the dispersion includes treatment by mechanical stirring or ultrasonic dispersion for 1 min to 2 h; The stirring rate of the mechanical stirring is 400~1500 rpm; The frequency of the ultrasonic dispersion is 28~40 kHz.

[0018] As a preferred embodiment of any technical solution in the second aspect of the present invention, in step (2), the drying is performed at a temperature of 60~90°C for 10~30 minutes. As a preferred embodiment of any technical solution in the second aspect of the present invention, in step (2), the polymer includes one or more of cross-linked sodium alginate, polyvinyl alcohol, polyethylene oxide, waterborne polyurethane, thermoplastic polyurethane, polyvinylidene fluoride-hexafluoropropylene copolymer, and ethylene-vinyl acetate copolymer.

[0019] Further preferably, in step (2), the polymer includes one or more of cross-linked sodium alginate, polyvinyl alcohol, polyethylene oxide, and waterborne polyurethane.

[0020] In a further preferred embodiment, the cross-linked sodium alginate is a cross-linked product of sodium alginate and a salt containing divalent metal ions.

[0021] If the polymer in step (2) is cross-linked sodium alginate, then the second aspect of the present invention provides a method for preparing a metal gel current collector, specifically including the following steps: S1: Disperse the conductive active core and liquid metal in an acid solution or alkaline solution, separate and wash to obtain a liquid metal composite; S2: Mix the liquid metal composite with sodium alginate solution for 10-30 min and dry to form a film; S3: Immerse the membrane obtained in step S2 in a crosslinking agent solution to undergo a crosslinking reaction for 5-10 min to obtain a metal gel current collector.

[0022] In step S1, the mass ratio of the liquid metal to the conductive active core is 100:(3~80); and / or, In step S2, the mass ratio of the liquid metal composite to the sodium alginate is (18~95):1.

[0023] In step S3, the crosslinking agent includes a salt containing divalent metal ions, and the molar ratio of sodium alginate to crosslinking agent in the crosslinking reaction is (1.5~2.5):1.

[0024] More preferably, in step S3, the crosslinking agent includes one or more of calcium salts and zinc salts. When the polymer is cross-linked sodium alginate, under this premise, the conditions that step S1 and step (1), step S2 and step (2) need to meet are the same as when the polymer is not cross-linked sodium alginate.

[0025] It should be noted that the three-dimensional gel network has three characteristics: First, its three-dimensional network structure provides more electrode / electrolyte contact sites; second, when in contact with the electrolyte, the three-dimensional gel network can swell by absorbing some of the electrolyte, further increasing the reaction interface; third, due to its gel properties, the three-dimensional gel network has a certain degree of fluidity, and during the metal ion deposition / stripping process, it can follow the electrode deformation and dynamically adjust the interface contact state, avoiding problems such as poor battery cycle stability and poor safety caused by cracking of traditional rigid current collectors (metal sheets, porous graphene, carbon nanotubes, etc.) with the electrode, uneven distribution of electrolyte on the surface, and local heating.

[0026] As a preferred embodiment of any technical solution in the second aspect of the present invention, it further includes: activating the metal gel current collector obtained in step (2) by charging and discharging.

[0027] The charge-discharge activation includes using the metal gel current collector as the working electrode to construct a three-electrode system or a two-electrode system, and performing metal deposition and stripping on or around the conductive active core.

[0028] In the three-electrode system, both the counter electrode and the reference electrode are metals, and the electrolyte is a metal-containing salt; in the two-electrode system, the counter electrode is a metal, and the electrolyte is a metal-containing salt.

[0029] It should be noted that the charge-discharge activation can make the conductive active cores in the metal gel current collector more uniformly distributed.

[0030] As a preferred embodiment of any technical solution in the second aspect of the present invention, the conditions for charge-discharge activation include: The current density is 0.1~5 mA·cm. 2 ; Charge-discharge cycles: 5-40 times; Each cycle consists of 10-60 minutes of charging and 10-60 minutes of discharging.

[0031] A third aspect of the present invention provides an electrode comprising: a carrier and a metal located on the carrier; Wherein, the carrier is a metal gel current collector provided by any technical solution of the first aspect of the present invention or a metal gel current collector prepared by any technical solution of the second aspect of the present invention; The metal includes one or more of lithium, zinc, magnesium, aluminum, and sodium; The metal is located on and around the surface of the conductive active core in the metal gel current collector; The metal accounts for 65-95% of the mass of the electrode. A fourth aspect of the present invention provides a method for preparing the electrode provided in the third aspect of the present invention, wherein the electrode is prepared by electrochemical deposition, and the conditions for the electrochemical deposition include: The metal gel current collector serves as the working electrode; The metal target is used as the counter electrode; A metal target, a saturated calomel electrode, or an Ag / AgCl electrode serves as the reference electrode. Electrolytes are salts of metals; The current density is 0.1~5 mA·cm. 2 ; The deposition time is 0.6 to 30 days.

[0032] A fifth aspect of the present invention provides a battery comprising: The negative electrode is an electrode provided by any technical solution of the third aspect of the present invention or an electrode prepared by any technical solution of the fourth aspect of the present invention. positive electrode; Electrolytes; and / or, Diaphragm.

[0033] A sixth aspect of the present invention provides a flexible battery comprising: The negative electrode is an electrode provided by any technical solution of the third aspect of the present invention or an electrode prepared by any technical solution of the fourth aspect of the present invention. Flexible positive electrode; Flexible solid or semi-solid electrolytes; and / or, Diaphragm.

[0034] 3. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The metal gel current collector provided by the present invention has a structure in which a liquid metal coated conductive active core forms a liquid metal complex, and the liquid metal complex is fixed in a three-dimensional gel network, and the three-dimensional gel network has ionic conductivity. The metal gel current collector provided by the present invention can form ion and electron conduction pathways. Based on this structure, on the one hand, the three-dimensional gel network can provide sufficient electrode / electrolyte interface contact sites. Compared with traditional planar current collectors modified with coatings, the metal gel current collector provided by this invention has reduced charge transfer resistance, effectively improving ion migration rate and accelerating reaction kinetics, thus meeting the requirements for rapid charge and discharge. On the other hand, the three-dimensional gel network only allows metal ions (such as zinc ions and lithium ions) to pass through, blocking H+. +The metal gel current collector, containing H2O, provides active sites for deposition / stripping of metals (such as zinc and lithium) by a conductive active core, guiding the deposition / stripping of metals. This conductive active core is then coated with liquid metal, forming a protective layer that further prevents direct contact between the electrolyte and the electrode. Compared to existing porous current collectors, the metal gel current collector provided by this invention effectively suppresses parasitic reactions and dendrite formation, improving cycle stability. Therefore, the metal gel current collector provided by this invention achieves a synergistic balance between "high reaction kinetics" and "long cycle stability." Furthermore, in the metal gel current collector provided by this invention, the mass ratio of liquid metal composite is relatively high, while the proportion of three-dimensional gel network is relatively low, which can largely ensure the electron transport performance of the metal gel current collector.

[0035] (2) The metal gel current collector provided by the present invention uses liquid metal and three-dimensional gel network, both of which have certain fluidity. It can repair certain interface defects through flow, avoid the formation of micro protrusions due to excessive local deposition of metal ions (such as zinc ions and lithium ions), and thus avoid dendrite formation. It fundamentally eliminates the possibility of dendrite formation and improves the safety and stability of the battery.

[0036] (3) The preparation method of the metal gel current collector provided by the present invention uses raw materials such as polymers, liquid metals, and conductive active cores, which are all industrially mass-produced raw materials. Compared with traditional porous carbon-based current collectors, the cost is low, and the preparation method does not require high-temperature sintering, and the energy consumption is low and simple and fast.

[0037] (4) The battery provided by the present invention includes an electrode prepared using the metal gel current collector provided by the present invention as a carrier. The metal gel current collector provides more ion and electron conduction pathways, expands the reaction interface, and has a smaller interface resistance. It can maintain a low overpotential under high current density and can achieve fast charging and discharging. At the same time, the metal gel current collector has a special structure with a three-dimensional gel network to fix the liquid metal composite and liquid metal to coat the conductive active core, which avoids the formation of dendrites during battery use and inhibits parasitic reactions, and can effectively improve the cycle stability of the battery and improve the battery life. In addition, the electrodes prepared using metal gel current collectors as carriers also have good flexibility. Combined with flexible positive electrodes and flexible electrolytes, the battery as a whole can be used in the field of wearable electronic devices, and also has the characteristics of high-rate charge and discharge and long-term cycle stability. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the preparation process of the metal gel current collector in Example 1; Figure 2 This is a schematic diagram of the metal gel current collector in Example 1; Figure 3This is a schematic diagram of the charging and discharging activation process of the metal gel current collector in Example 1; Figure 4 This is a SEM-EDS image of the interior of the metal gel current collector in Example 1; Figure 5 The figures show XPS spectra of the surface and interior of the liquid metal composite in Example 1. In the figures, a is the XPS spectrum of Zn on the surface and interior of the liquid metal composite; b is the XPS spectrum of Ga and In on the surface and interior of the liquid metal composite. Figure 6 Fluorescence imaging of the process of adding electrolyte to the metal gel current collector in Test Example 1; Figure 7 The constant current charge-discharge curves of different symmetrical batteries in Example 3 and Comparative Example 2 are shown. Figure 8 The overpotential curve of the symmetrical cell in Example 3; Figure 9 The zinc-air battery in Example 4 operates at a current density of 0.05 mA·cm⁻¹. -2 Constant current charge-discharge curve at time; Figure 10 For example 4 and comparative example 3, different zinc-air batteries were used at a current density of 1 mA·cm⁻¹. -2 Constant current charge-discharge curve at time; Figure 11 The figures show the charge-discharge curves of the flexible zinc-air battery under different deformation conditions in Example 5. Detailed Implementation

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0040] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0041] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as "less than about 4.5," which should be interpreted to include all the values ​​and ranges described above. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0042] The present invention will be further described below with reference to specific embodiments.

[0043] Raw materials and instruments used in the embodiments Zinc granules: 100μm in diameter; Sinopharm Chemical Reagent Co., Ltd. Gallium-indium alloy: Ga:In mass ratio 75:25; Sigma-Aldrich Trading Co., Ltd. Sodium alginate: purity ≥90%, Shanghai Maclean Biochemical Co., Ltd.; Polyvinyl alcohol: DP: 1750±50, Shanghai Yuanye Biotechnology Co., Ltd.; Stainless steel current collector: a stainless steel disc containing 18% chromium and 8% nickel, with a diameter of 10mm and a thickness of 0.5mm, purchased from Guangdong Kelude New Energy Technology Co., Ltd. Carbon nanotube current collector: a circular disc with a diameter of 10 mm and a thickness of 20 μm, purchased from Tianfeng Technology Co., Ltd.; Carbon black: particle size 20~50 nm, Wuhu Owl Materials Technology Co., Ltd. Nickel foam: 0.5mm thick, Suzhou Shengernuo Technology Co., Ltd. LANHE Battery Testing System: Model CT2001A, Wuhan Landian Electronics Co., Ltd.; Zinc foil: 30μm thickness, Qinghe County Shengyuan Metal Materials Purchasing and Sales Department; Fiberglass diaphragm: Model 1820-150, Shanghai Dingze Industrial Co., Ltd.

[0044] Example 1 According to such Figure 1 The process shown is for preparing metal gel current collectors, and the specific steps are as follows: 1. Preparation of liquid metal composites Take 5.36 g of gallium-indium alloy (liquid metal) and 0.64 g of zinc particles (conductive active core) and disperse them in 10 mL of 1 mol / L hydrochloric acid solution, and stir at 400 rpm for 10 minutes to make the zinc particles uniformly suspended in the gallium-indium alloy phase; Subsequently, the hydrochloric acid solution was discarded, and the mixture was washed with deionized water until neutral to completely remove residual hydrochloric acid, yielding a dual-phase gallium-indium-zinc alloy (solid phase being zinc particles, liquid phase being gallium-indium alloy), i.e., a liquid metal composite, wherein the mass ratio of liquid metal to conductive active core is 100:11.9.

[0045] 2. Prepare polymer solution Polyvinyl alcohol and sodium alginate were dissolved in deionized water and stirred continuously at 80°C for 2 hours to prepare a polymer solution, wherein the concentration of polyvinyl alcohol was 5 wt% and the concentration of sodium alginate was 2 wt%.

[0046] 3. Add 6g of the described biphase gallium indium zinc alloy to 4g of the polymer solution, and homogenize using a handheld homogenizer for 10 minutes to form a uniform precursor solution. Cast 10g of this precursor solution into a polytetrafluoroethylene petri dish (radius = 70mm) and dry at 60°C for 30 minutes to remove moisture, obtaining a gallium indium zinc-polymer film. In the dried gallium indium zinc-polymer film after solvent removal, zinc particles are coated in the gallium indium alloy, forming a gallium indium zinc continuum dispersed in the polymer. Since gallium and indium are liquid metals, they are interconnected, forming electronic pathways.

[0047] 4. Immerse the gallium indium zinc (CIZ) polymer film in a 0.1 mol / L zinc sulfate (crosslinking agent) solution for 5 min to carry out the crosslinking reaction. The molar ratio of sodium alginate to zinc sulfate in the CIZ polymer film is 2:1. After the reaction, the structure shown is obtained. Figure 2 The metal gel current collector shown is wherein the mass of the liquid metal composite accounts for 95% of the mass of the metal gel current collector.

[0048] During use, the metal gel current collector comes into contact with the electrolyte, and the three-dimensional gel network can transport ions, forming an ion pathway.

[0049] 5. The metal gel current collector obtained in step 4 is activated by constant current charge and discharge in a three-electrode system to make the zinc distribution more uniform, specifically as follows: The product obtained in step 4 was used as the working electrode, zinc foil (zinc target) served as both the counter electrode and the reference electrode, and zinc sulfate solution was used as the electrolyte. The test was conducted on a LANHE battery testing system with a current density of 0.5 mA·cm⁻¹. -2The activated metal gel current collector underwent 20 cycles of charge-discharge activation, with each cycle consisting of 1 hour of discharge (zinc stripping) and 1 hour of charge (zinc deposition). This resulted in a more uniform distribution of the conductive active cores within the activated metal gel current collector. A schematic diagram of the charge-discharge activation process is shown below. Figure 3 As shown, the activated metal gel current collector was used in the following embodiments to prepare the electrodes and batteries.

[0050] Example 2 The zinc electrode was prepared using the metal gel current collector from Example 1 as the carrier, and zinc as the target metal. The specific steps are as follows: Using the metal gel current collector from Example 1 as the working electrode, zinc foil as both the counter electrode and the reference electrode, and zinc sulfate solution as the electrolyte, at a current density of 1.0 mA·cm⁻¹ -2 Electrochemical deposition was carried out under certain conditions for 3 days until the deposited zinc accounted for 65% of the total mass of the zinc electrode.

[0051] Example 3 Preparation of symmetric cells Cut the zinc electrode from Example 2 and cut out two circular pieces with a diameter of 10 mm and a thickness of 200 μm to serve as the positive and negative electrodes of the symmetrical battery, respectively. Use two glass fibers with a diameter of 18 mm as separators and add 0.3 mL of 1 mol / L zinc sulfate solution between the two separators as electrolyte. Assemble the battery into the CR2032 button cell casing in the order of negative electrode | separator | electrolyte | separator | positive electrode. Seal the button cell under controlled pressure of 750 psi using a battery packaging machine.

[0052] All assembly and sealing steps were performed at ambient temperature and pressure.

[0053] Example 4 Preparation of zinc-air batteries The only difference between this embodiment and embodiment 3 is that: (1) the positive electrode material used is different, the positive electrode of this embodiment is a carbon-based air electrode; (2) the electrolyte used is different, the electrolyte of this embodiment is 0.3 mL 1 mol / L zinc trifluoromethanesulfonate solution.

[0054] The preparation steps of the carbon-based air electrode are as follows: 1) Mix carbon black and polytetrafluoroethylene binder (polytetrafluoroethylene concentration is 10 wt% aqueous dispersion) in an agate mortar at a mass ratio of 9:1, and then add an appropriate amount of isopropanol to form a uniform paste. 2) Coat the paste from step 1) onto nickel foam and let it stand at room temperature for 24 hours to remove the solvent, thus obtaining a carbon-based air electrode. Example 5 Fabrication of flexible zinc-air batteries Cut the zinc electrode in Example 2, and cut out a circular piece with a diameter of 10 mm and a thickness of 200 μm as the negative electrode. Prepare a flexible carbon-based air electrode as the positive electrode. A flexible semi-solid electrolyte with a thickness of 1 mm is sandwiched between the positive and negative electrodes, and the area of ​​the flexible semi-solid electrolyte is slightly larger than or equal to the area of ​​the positive and negative electrodes. Then, a flexible zinc-air battery is assembled in the order of negative electrode | electrolyte | positive electrode, and encapsulated with a polyethylene film to improve its mechanical stability.

[0055] The preparation steps of the flexible carbon-based air electrode are as follows: 1) Place ethylene-vinyl acetate in m-xylene and stir at 60°C for 2 hours to completely dissolve the ethylene-vinyl acetate, at which point the concentration of ethylene-vinyl acetate is 5 wt%. 2) Add 0.45g of carbon black to 5g of the ethylene-vinyl acetate solution from step 1), and stir until homogeneous; 3) The mixed solution from step 2) is uniformly coated onto the sugar cube template and vacuum dried at 60°C for 12 hours. Then, it is immersed in water to dissolve the sugar cube template, resulting in a flexible carbon-based air electrode of 60 (length) × 60 (width) × 0.5 (thickness) mm.

[0056] The preparation steps of the flexible semi-solid electrolyte are as follows: A: Place acrylamide, zinc trifluoromethanesulfonate, and methylenebisacrylamide in deionized water and stir to dissolve, forming a mixed solution with acrylamide concentration of 2 M, zinc trifluoromethanesulfonate concentration of 1 M, and a methylenebisacrylamide:acrylamide mass ratio of 0.14:100.

[0057] B: Keep the mixture in A under stirring, add 0.015 g of ammonium persulfate to 3 ml of the mixture in A, and continue stirring for 30 min until completely dissolved; C: Pour the mixed solution after step B into a petri dish and perform thermal crosslinking at 60°C for 1 hour to obtain polyacrylamide / zinc trifluoromethanesulfonate hydrogel electrolyte, i.e., flexible semi-solid electrolyte.

[0058] Comparative Example 1 The only difference between this comparative example and Example 2 is the carrier used to prepare the zinc electrode. This comparative example uses a stainless steel current collector and a carbon nanotube current collector as carriers to prepare the corresponding zinc electrodes, denoted as the stainless steel current collector zinc electrode and the carbon nanotube current collector zinc electrode, respectively. The absolute mass of zinc loaded on the stainless steel current collector zinc electrode and the carbon nanotube current collector zinc electrode is the same as that of the zinc electrode prepared in Example 2.

[0059] Comparative Example 2 Preparation of stainless steel current collector-symmetric cells and carbon nanotube current collector-symmetric cells The only difference between this comparative example and Example 3 is the use of different electrodes. This comparative example uses the stainless steel current collector zinc electrode prepared in Comparative Example 2 as the positive and negative electrodes to prepare a stainless steel current collector-symmetric cell; and uses the carbon nanotube current collector zinc electrode prepared in Comparative Example 2 as the positive and negative electrodes to prepare a carbon nanotube current collector-symmetric cell.

[0060] Comparative Example 3 Preparation of stainless steel current collector-zinc air batteries and carbon nanotube current collector-zinc air batteries The only difference between this comparative example and Example 4 is the use of a different negative electrode. This comparative example uses the stainless steel current collector zinc electrode prepared in Comparative Example 2 as the negative electrode to prepare a stainless steel current collector-zinc air battery; and uses the carbon nanotube current collector zinc electrode prepared in Comparative Example 2 as the negative electrode to prepare a carbon nanotube current collector-zinc air battery.

[0061] Test Example 1 This test example characterizes the metal gel current collector prepared in Example 1 using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), and fluorescence microscopy. The results are as follows: Figure 4 The image shows the SEM-EDS image of the metal gel current collector in Example 1. As can be seen from the image, there are Ga, Zn and C elements inside the metal gel, indicating that Zn has entered the liquid metal. C represents that the metal gel current collector contains polymers.

[0062] Figure 5 These are XPS spectra of the surface and interior of the liquid metal composite in Example 1, obtained from... Figure 5 As can be seen, the Zn content inside the liquid metal composite is much higher than the Zn content on its surface, while the surface of the liquid metal composite contains very little Zn. Figure 5 b shows that the liquid metal composite contains Ga and In elements both on the surface and inside, with a slightly lower content inside. Combined with... Figure 5 a, Figure 5 b indicates that the liquid metal composite forms a structure in which liquid metal (Ga, In) coats a conductive active core (Zn).

[0063] A fluorescent agent was added to the electrolyte (zinc sulfate solution), and the metal gel current collector prepared in Example 1 was immersed in the electrolyte. The immersion process was observed under a fluorescence microscope, and the results were as follows. Figure 6As shown: Initially, the boundary between the metal gel current collector and the electrolyte is clear. After soaking for 5 minutes, it can be observed that some of the metal gel current collector has fluorescence and presents a three-dimensional network shape. Non-fluorescent substances are fixed in the middle of the network. This is because the cross-linked sodium alginate absorbs the electrolyte containing fluorescent substances and emits light. This proves that a liquid metal complex dispersed in a three-dimensional gel network structure has been formed.

[0064] Figures 4-6 The results show that the metal gel current collector prepared in Example 1 has a structure in which a liquid metal coated conductive active core forms a liquid metal composite, and the liquid metal composite is fixed in a three-dimensional gel network.

[0065] Test Example 2 Using symmetrical cell testing effectively eliminates the influence of chemical / electrochemical differences between the positive and negative electrode materials on the test results, providing a clearer and more intuitive reflection of the performance of a single electrode material. This test example applies constant current charge-discharge cycle (GCD) testing to different symmetrical cells prepared in Example 3 and Comparative Example 1 under the same conditions. The results are as follows: Figure 7 , 8 As shown: The symmetric cell prepared in Example 3 (corresponding to) Figure 7 The medium-sized metal gel current collector has an areal capacity of 75 mAh. cm -2 The current density is 10 mA·cm -2 Under these conditions, it achieved 80% depth of discharge and remained stable for 4383 hours, with the voltage consistently near 0V (the typical operating voltage range of zinc batteries), showing no obvious signs of failure and demonstrating excellent high-load, long-cycle stability; while the stainless steel current collector-symmetric battery prepared in Comparative Example 1 (corresponding to Figure 7 The stainless steel current collector in Example 1 exhibited a "zinc deficiency" problem within approximately 12 hours of cycling, and experienced severe voltage fluctuations, leading to rapid failure. In Comparative Example 1, the carbon nanotube current collector-symmetric battery (corresponding to...)... Figure 7 The carbon nanotube fluid in the cell exhibited a "short circuit" problem in the early stages of cycling and failed after about 12 hours of cycling. Its cycling stability was much weaker than that of the symmetrical battery composed of zinc electrodes constructed with metal gel current collectors (Example 3).

[0066] The symmetric cell prepared in Example 3 was further subjected to galvanostatic charge-discharge cycle (GCD) testing with increased current density, and the results are as follows: Figure 8 As shown: The symmetric cell prepared in Example 3, namely the symmetric cell composed of a zinc electrode constructed from a metal gel current collector, even achieved a speed of 100 mA·cm⁻¹. -2The fact that the battery can maintain a low overpotential of 156.7 mV even under high current density indicates that the reaction has a small kinetic barrier and that the deposition / stripping of the zinc anode on the electrode surface can proceed smoothly under high current, enabling rapid charge and discharge. At the same time, it reflects that the symmetrical battery has good interface stability and does not exhibit phenomena such as dendrites or side reactions that would cause the overpotential to spike.

[0067] Test Example 3 This test example compares the zinc-air batteries prepared in Example 4 and Comparative Example 2 under the same conditions and performs constant current charge-discharge cycle (GCD) tests. The results are as follows: Figure 9 , Figure 10 As shown: Figure 9 The constant current charge-discharge curve of the zinc-air battery prepared in Example 4 shows that it can achieve a constant current charge-discharge rate of 0.05 mA·cm⁻¹. -2 It can cycle stably for 1600 hours at a current density.

[0068] Figure 10 To increase the test results of different zinc-air batteries prepared in Example 4 and Comparative Example 2 under different current densities, it can be clearly observed from the figure that the stainless steel current collector-zinc-air battery and the carbon nanotube current collector-zinc-air battery prepared in Comparative Example 2 experience a rapid voltage drop and battery failure, while the zinc-air battery prepared in Example 4 (corresponding to...) Figure 10 (Metal-based gel current collector) at 1 mA·cm -2 It achieves a discharge depth of 50% at a given current density and cycles stably for over 240 hours, demonstrating excellent cycle stability.

[0069] The test results show that the zinc-air battery prepared in Example 4 can achieve stable charge and discharge at a high current density, proving that it achieves a balance between "high reaction kinetics" and "long cycle stability", and has both high rate performance and long-term cycle stability.

[0070] Test Example 4 To verify that the flexible zinc-air battery prepared in Example 5 also possesses good flexibility, this test example underwent different artificial deformations, and its electrical performance under deformation conditions was tested. The results are as follows: Figure 11 As shown: After being bent at 90°, twisted at 90°, and subjected to compressive shear force, the flexible zinc-air battery prepared in Example 5 maintained a stable charge-discharge voltage after 1000 cycles, indicating that the flexible zinc-air battery prepared in Example 5 also has good flexibility and good cycle stability under deformation, showing promise for application in the field of wearable electronic devices.

[0071] The above description provides an illustrative overview of the present invention and its embodiments. This description is not restrictive, and the embodiments shown are merely one example of the invention's implementation. Actual implementations are not limited to these examples. Therefore, if those skilled in the art are inspired by this description and design similar implementations and examples without departing from the spirit of the invention, such designs should fall within the scope of protection of the present invention.

Claims

1. A metal gel current collector, characterized in that, Includes a three-dimensional gel network and a liquid metal complex dispersed in the three-dimensional gel network; The three-dimensional gel network has ionic conductivity; The liquid metal composite is a mixture in which liquid metal is the continuous phase and the liquid metal is coated with a conductive active core. The conductive active core comprises particles of one or more of zinc, copper, nickel, and silicon. The mass of the liquid metal composite accounts for 90-95% of the mass of the metal gel current collector; The mass ratio of the liquid metal to the conductive active core is 100:(3~80).

2. The metal gel current collector according to claim 1, characterized in that; The liquid metal includes one or more of gallium (Ga) metal, gallium-indium alloy, and gallium-indium-tin alloy; The three-dimensional gel network is formed by cross-linking one or more of the following: sodium alginate, polyvinyl alcohol, polyethylene oxide, waterborne polyurethane, thermoplastic polyurethane, polyvinylidene fluoride-hexafluoropropylene copolymer, and ethylene-vinyl acetate copolymer.

3. A method for preparing a metal gel current collector, characterized in that, Includes the following steps: (1) The conductive active core and liquid metal are dispersed in an acid solution or an alkaline solution, separated and washed to obtain a liquid metal composite; wherein the conductive active core includes one or more particles of zinc, copper, nickel and silicon; (2) The liquid metal composite is mixed with the polymer solution for 10-30 min and dried to form a film to obtain a metal gel current collector; Wherein, the mass ratio of the liquid metal to the conductive active core in step (1) is 100:(3~80); and / or, In step (2), the mass ratio of the liquid metal composite to the polymer is (18~95):

1.

4. The method for preparing the metal gel current collector according to claim 3, characterized in that, In step (1), the liquid metal includes one or more of gallium metal, gallium-indium alloy, and gallium-indium-tin alloy; the acid solution is a strong acid solution with a hydrogen ion concentration of 0.1~1 mol / L; the alkaline solution is a strong alkaline solution with a hydroxide ion concentration of 0.1~1 mol / L; and / or, In step (2), the polymer includes one or more of cross-linked sodium alginate, polyvinyl alcohol, polyethylene oxide, waterborne polyurethane, thermoplastic polyurethane, polyvinylidene fluoride-hexafluoropropylene copolymer, and ethylene-vinyl acetate copolymer.

5. The method for preparing the metal gel current collector according to any one of claims 3 to 4, characterized in that, Also includes: The metal gel current collector obtained in step (2) is activated by charge and discharge.

6. The method for preparing the metal gel current collector according to claim 5, characterized in that, The conditions for charge and discharge activation include: The current density is 0.1~5 mA·cm. 2 ; Charge-discharge cycles: 5-40 times; Each cycle consists of 10-60 minutes of charging and 10-60 minutes of discharging.

7. An electrode, characterized in that, The electrode includes: a carrier and a metal located on the carrier; Wherein, the carrier is the metal gel current collector according to any one of claims 1 to 2 or the metal gel current collector prepared by the method according to any one of claims 3 to 6; The metal includes one or more of lithium, zinc, magnesium, aluminum, and sodium; The metal is located on and around the surface of the conductive active core in the metal gel current collector; The metal accounts for 65-95% of the mass of the electrode.

8. The method for preparing the electrode according to claim 7, characterized in that, The electrode is prepared by electrochemical deposition, wherein the conditions for electrochemical deposition include: The metal gel current collector serves as the working electrode; The metal target is used as the counter electrode; A metal target, a saturated calomel electrode, or an Ag / AgCl electrode serves as the reference electrode. Electrolytes are salts of metals; The current density is 0.1~5 mA·cm. 2 ; The deposition time is 0.6 to 30 days.

9. A battery, characterized in that, Include: The negative electrode is the electrode described in claim 7 or the electrode prepared by the method described in claim 8; positive electrode; Electrolytes; and / or, Diaphragm.

10. A flexible battery, characterized in that, Include: The negative electrode is the electrode described in claim 7 or the electrode prepared by the method described in claim 8; Flexible positive electrode; Flexible solid or semi-solid electrolytes; and / or, Diaphragm.

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