A wide-temperature-range long-life flexible zinc-lithium hybrid ionic battery hydrogel electrolyte and a preparation method and application thereof
By improving the hydrogel electrolyte framework and electrolyte system, the problems of freezing and dendrite growth at low temperatures were solved, achieving high efficiency and safety of flexible zinc-lithium batteries in extreme environments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG UNIV
- Filing Date
- 2026-02-06
- Publication Date
- 2026-06-09
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to a wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery hydrogel electrolyte, its preparation method, and its application, belonging to the field of flexible energy storage device technology. Background Technology
[0002] With the rapid development of flexible electronics, smart wearable devices, and soft robots, the market has an urgent need for flexible energy storage devices that can withstand bending, folding, and even stretching deformation. Among numerous candidate systems, aqueous zinc-lithium hybrid batteries (Zn-Li Hybrid Batteries) combine the high theoretical capacity (820 mAh g) of the zinc anode. -1 The advantages of low cost, as well as the high operating voltage and fast dynamic characteristics of lithium-ion battery cathodes (such as lithium manganese oxide and lithium iron phosphate), are considered to be the next generation of highly competitive flexible power solutions.
[0003] To achieve device flexibility and eliminate the risk of electrolyte leakage, hydrogel electrolytes are gradually replacing traditional liquid electrolytes. In particular, sodium alginate / polyacrylamide (SA / PAM) dual-network hydrogels have become an ideal matrix material for constructing flexible zinc-based batteries due to their excellent mechanical strength, high toughness, and good biocompatibility. Despite significant advancements in the mechanical properties of existing SA / PAM hydrogel electrolytes (as reported in the literature, they can withstand substantial stretching), the following technical bottlenecks remain insurmountable in terms of extreme environmental adaptability and electrochemical interface stability: Technical Issue 1: Low-Temperature "Freezing" and Conductivity Failure of Hydrogels (Temperature Range Limitation) Conventional SA / PAM hydrogel electrolytes contain a large amount of free water. When the ambient temperature is below 0°C, water molecules within the gel network readily form long-range ordered ice lattices. This not only causes the gel to harden and become brittle, losing its flexibility (i.e., "brittle fracture"), but more seriously, it completely blocks ion transport channels, leading to a sharp increase in the battery's internal resistance and preventing it from functioning properly in cold environments (such as outdoor wear or high-altitude work).
[0004] Current dilemma: Although introducing high-concentration salt (Water-in-Salt) doi: 10.3866 / PKU.WHXB202211005 or traditional antifreeze agents (such as glycerol and ethylene glycol) can lower the freezing point, the former leads to high gelation costs and easy salt precipitation, while the latter often significantly increases electrolyte viscosity and reduces ion mobility, thereby sacrificing the rate performance of the battery.
[0005] Technical Issue 2: Dendrite growth and contact failure at the gel-electrode interface (cycle life limitation) During repeated deformation and charge / discharge processes in flexible devices, uneven electric field distribution easily occurs on the surface of the zinc anode. Although traditional SA / PAM hydrogels are macroscopically solid, their microscopic porous structure makes it difficult to effectively physically prevent zinc dendrites from penetrating. Sharp dendrite growth can not only pierce the gel and cause short circuits, but also lead to the accumulation of "dead zinc".
[0006] In addition, the active water molecules in the gel can easily induce hydrogen evolution reaction (HER) on the zinc anode surface. The generated hydrogen bubbles will accumulate at the interface between the gel and the electrode, causing physical delamination between the electrolyte layer and the electrode layer. This results in a sharp increase in contact impedance and rapid capacity decay of the flexible device after long-term cycling.
[0007] Technical Issue 3: Dissolution of cathode materials in hydrogel environments (chemical stability limitations) For zinc-lithium hybrid systems, manganese-based cathodes (such as LiMn2O4) face severe manganese dissolution problems in hydrogels. Existing SA / PAM hydrogels are usually only soaked in simple zinc salt solutions (such as zinc sulfate), lacking a protection mechanism for the cathode interface, which cannot effectively inhibit the loss of active materials, resulting in an unstable voltage plateau and short cycle life of the full cell.
[0008] Currently, the industry lacks a hydrogel electrolyte system that can simultaneously achieve high mechanical toughness, ultra-low temperature freeze resistance (-40°C level), and excellent interfacial chemical stability. Simple physical blending modification often results in one thing being neglected: improving freeze resistance often sacrifices mechanical strength, while improving mechanical strength often overlooks the passivation protection of the electrochemical interface.
[0009] Therefore, how to achieve freeze resistance and excellent interfacial chemical stability while maintaining the excellent mechanical properties of SA / PAM dual-network hydrogels through molecular-level design, and suppress dendrites and side reactions, is a key technical challenge for realizing high-performance flexible wide-temperature-range zinc-lithium hybrid ion batteries. Summary of the Invention
[0010] To address the technical problems in existing aqueous zinc-lithium hybrid ion batteries and flexible hydrogel electrolyte technologies, such as the loss of flexibility and sharp drop in ionic conductivity of hydrogels due to internal water freezing at low temperatures, and the susceptibility of zinc anodes to dendrite growth, hydrogen evolution corrosion, and dissolution of manganese-based cathodes during long-term cycling, which lead to short cycle life and low coulombic efficiency of flexible devices, this invention provides a wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery hydrogel electrolyte, its preparation method, and its application.
[0011] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery hydrogel electrolyte includes a polymer hydrogel framework and an electrolyte phase adsorbed and filled inside the framework. The polymer hydrogel framework is an interpenetrating double network structure formed by sodium alginate (SA) and polyacrylamide (PAM). The electrolyte phase includes a mixed solvent, an electrolyte salt, and functional additives; The mixed solvent is composed of water (H2O) and a co-solvent; the electrolyte salt is zinc trifluoromethanesulfonate (Zn(OTf)2) and lithium trifluoromethanesulfonate (LiOTf); and the functional additive is an alkali metal salt or a rare earth metal salt.
[0012] According to the present invention, the cosolvent is preferably dimethyl sulfoxide (DMSO), ethylene glycol (EG), glycerol, or acetonitrile, with dimethyl sulfoxide (DMSO) being the most preferred. DMSO offers the best balance between binding energy with water and low-temperature conductivity.
[0013] According to a preferred embodiment of the present invention, the volume percentage of the co-solvent in the mixed solvent is 20-60%, preferably 30-50%.
[0014] According to a preferred embodiment of the present invention, the concentration of zinc trifluoromethanesulfonate (Zn(OTf)2) in the electrolyte phase is 0.5-2 mol / L, preferably 1 mol / L, and the concentration of lithium trifluoromethanesulfonate (LiOTf) is 2-4 mol / L, preferably 3 mol / L.
[0015] According to a preferred embodiment of the present invention, the rare earth metal in the functional additive is selected from one or more combinations of cerium (Ce), lanthanum (La), yttrium (Y), neodymium (Nd), europium (Eu), or gadolinium (Gd); the alkali metal is selected from one or two combinations of cesium (Cs) or rubidium (Rb); and the alkali metal salt or rare earth metal salt is selected from one or more combinations of chloride, nitrate, or trifluoromethane sulfonate. All rare earth metal elements are trivalent cations, with a standard reduction potential significantly lower than zinc (<-2.3V vs. SHE), and possess high charge density. They can form an effective electrostatic shielding layer on the zinc anode surface to suppress dendrites, and can also form high-strength trivalent coordination crosslinking centers with the carboxyl groups on the sodium alginate molecular chain, maintaining the mechanical properties of the hydrogel. (Cs) + and Rb + It has an extremely low standard reduction potential and can preferentially adsorb onto electrode protrusions to provide electrostatic shielding and smooth the electric field distribution.
[0016] Preferably, the functional additive is cerium chloride (CeCl3) or lanthanum chloride.
[0017] According to a preferred embodiment of the present invention, the concentration of the functional additive in the electrolyte phase is 0.001-0.1 mol / L, preferably 0.005-0.05 mol / L.
[0018] This invention also provides a method for preparing the above-mentioned wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery hydrogel electrolyte, comprising the following steps: (1) Acrylamide (AM), sodium alginate (SA), crosslinking agent N,N'-methylenebisacrylamide (MBA), initiator and accelerator were dissolved in deionized water and SA / PAM original hydrogel was prepared by free radical polymerization reaction; (2) The original SA / PAM hydrogel is immersed in an electrolyte phase containing mixed solvent, electrolyte salt and functional additives. After soaking treatment, the water inside the original SA / PAM hydrogel is completely replaced by the electrolyte phase using the concentration diffusion principle, so as to obtain a flexible zinc-lithium hybrid ion battery hydrogel electrolyte with a wide temperature range and long life.
[0019] According to a preferred embodiment of the present invention, in step (1), the initiator is ammonium persulfate; the mass of the initiator is 1-5% of the mass of acrylamide, preferably 1%.
[0020] According to a preferred embodiment of the present invention, in step (1), the accelerator is tetramethylethylenediamine; the volume ratio of the accelerator to deionized water is 0.001-0.01:1.
[0021] According to a preferred embodiment of the present invention, in step (1), the mass ratio of acrylamide (AM), sodium alginate (SA), and crosslinking agent N,N'-methylenebisacrylamide (MBA) is 4-6:1:0.004-0.006, preferably 5:1:0.005; and the mass ratio of acrylamide to deionized water is 0.1-0.3 g / mL.
[0022] According to a preferred embodiment of the present invention, in step (1), the free radical polymerization reaction temperature is 40-80°C, and the reaction time is 4-8 hours. A degassing step is also included before the free radical polymerization reaction.
[0023] According to a preferred embodiment of the present invention, in step (2), the preparation method of the electrolyte phase is as follows: the electrolyte salt and functional additives are fully dispersed in a mixed solvent to obtain the electrolyte phase.
[0024] According to a preferred embodiment of the present invention, in step (2), the soaking temperature is room temperature, the soaking time is 4-8 hours, and the soaking is carried out under static conditions, with shaking every 2 hours during the process to accelerate diffusion equilibrium.
[0025] The present invention also provides the application of the above-mentioned hydrogel electrolyte in flexible zinc-lithium hybrid ion batteries.
[0026] According to a preferred embodiment of the present invention, the flexible zinc-lithium hybrid ion battery includes a positive electrode, a negative electrode, and the hydrogel electrolyte located between the two; wherein the positive electrode active material is lithium manganese oxide (LiMn2O4), and the negative electrode is zinc foil.
[0027] The technical features and beneficial effects of this invention are as follows: 1. Overcoming the bottleneck of low-temperature brittleness in traditional hydrogels, achieving dual retention of flexibility and conductivity in extremely cold environments. Existing SA / PAM hydrogels expand in volume, become mechanically hard and brittle (lose flexibility) and have their ion transport channels blocked when the internal free water freezes below 0°C.
[0028] This invention introduces dimethyl sulfoxide (DMSO) through a solvent displacement strategy.
[0029] At the microscopic physical level: DMSO, as a powerful polymer plasticizer and cryoprotectant, effectively inhibits the nucleation of tetrahedral ice crystals in water molecules by forming a strong hydrogen bond network with water molecules and polar groups (-OH, -CONH2) on the polymer chain, so that the hydrogel remains in a semi-solid gel phase without freezing at extremely low temperatures of -40°C.
[0030] At the macroscopic performance level, this design not only ensures high ionic conductivity at low temperatures, but more importantly, it maintains the mechanical flexibility of the hydrogel framework, solving the industry problem of electrolyte breakage failure caused by bending of conventional flexible batteries at low temperatures.
[0031] 2. Constructing a dual mechanism of "electrostatic shielding + physical barrier" to achieve ultra-long cycle life. To address the dendrite growth problem in zinc anodes, this invention utilizes the synergistic effect of a dense SA / PAM network and functional additives: Chemical inhibition (electrostatic shielding): Trace amounts of functional additives such as Ce are introduced into the electrolyte. 3+ Its reduction potential (-2.336 V) is much lower than that of Zn. 2+ According to the Nernst effect, Ce 3+ During charging, it preferentially adsorbs onto the highly active protrusions (i.e., dendrite growth points) on the surface of the zinc anode, forming an electrostatic shielding layer that repels Zn. 2+ It spread to that area, forcing Zn 2+ Deposited in the electrode recess, zinc is induced to deposit smoothly at the atomic scale.
[0032] Physical inhibition (mechanical barrier): SA / PAM dual-network hydrogel has high toughness and high modulus. As a quasi-solid electrolyte, its dense porous structure can effectively withstand the volume expansion stress during zinc deposition and physically block the penetration of sharp dendrites on a macroscopic scale.
[0033] The above-mentioned components work together synergistically to achieve thousands of cycles without short circuits.
[0034] 3. Rare earth ions enhance cross-linking, significantly improving the mechanical strength of hydrogels. Traditional SA hydrogels typically utilize divalent cations (such as Ca2+) 2+ Zn 2+ It forms an "egg-box" structure with the G block on the sodium alginate chain for ionic cross-linking.
[0035] The trivalent rare earth ions such as Ce introduced in this invention 3+ It has higher charge density and coordination ability. Ce 3+ With the carboxyl group (-COO) on the SA molecular chain - This forms stronger trivalent coordination crosslinking centers. This special metal-ligand interaction enables the hydrogel prepared by this invention to have higher tensile strength, tear resistance, and compressive fatigue resistance compared to hydrogels soaked in ordinary zinc salts, making it better suited to the large deformation requirements of wearable devices.
[0036] 4. In-situ film formation technology suppresses side reactions and solves the problem of "bulging" in flexible batteries. In a sealed pouch, aqueous batteries can bulge and delamination due to the accumulation of gas generated by the hydrogen evolution reaction (HER).
[0037] Functional additives in this invention, such as Ce 3+ When the pH of the electrode interface microenvironment increases, it transforms in situ into a dense and extremely thin cerium oxide / hydroxide (CeO2 / Ce(OH)3) passivation film (SEI). This "artificial skin" prevents direct contact between active water molecules and the zinc anode, significantly reducing the hydrogen evolution overpotential, inhibiting gas generation and zinc corrosion, and greatly improving the coulombic efficiency and cycle performance of the full cell.
[0038] 5. A dual-salt system stabilizes manganese-based cathodes, balancing high voltage and structural stability. This invention uses a Zn(OTf)2+ LiOTf bis(trifluoromethanesulfonate) system to replace the traditional sulfate system.
[0039] Inhibiting manganese dissolution: The "salt-encapsulated water" effect produced by high-concentration lithium salts reduces the activity of free water, effectively inhibiting the dissolution of Mn in the LiMn2O4 cathode. 3+ The disproportionation reaction.
[0040] Enhanced kinetics: Compared to sulfate (SO4) 2- ), large volume OTF -The high degree of charge delocalization of anions and low degree of association with cations are more conducive to the rapid dissociation and migration of ions at low temperatures, thus ensuring the rate performance of the battery at high voltages.
[0041] 6. Intrinsic security and process scalability This hydrogel electrolyte possesses intrinsic safety characteristics of being flame-retardant, non-toxic, and leak-proof, and will not burn or explode even under shearing, needle puncture, or severe impact. Furthermore, the "polymerization-displacement" process employed in this invention cleverly avoids interference from organic solvents on the polymerization reaction. The process is simple, easily compatible with existing production lines, and has extremely high prospects for industrial application.
[0042] 7. This invention achieves low-temperature antifreeze, dendrite suppression, and side reaction suppression simultaneously in zinc-lithium hybrid ion batteries through the synergistic design of a zinc-lithium dual-salt system, an organic co-solvent, and trace rare earth functional additives, thereby significantly improving the battery's electrochemical performance, such as wide-temperature-range cycle life. Attached Figure Description
[0043] Figure 1 This is a schematic diagram of a button battery assembly. Figure 2 This is a graph showing the mechanical properties of the hydrogel electrolyte prepared in Example 1 at 25°C; Figure 3 This is a graph showing the mechanical properties of the hydrogel electrolyte prepared in Example 1 at -20°C; Figure 4 The cycling characteristics curve of the button cell assembled with the hydrogel electrolyte prepared in Example 1 at 25 degrees Celsius and 2C current is shown. Figure 5 This is a graph showing the rate performance of a button cell assembled with the hydrogel electrolyte prepared in Example 1 at different temperatures. Figure 6 This is a compression deformation cycle diagram of the hydrogel electrolyte prepared in Example 1; Figure 7 The cycling characteristics curve of the button cell assembled with the hydrogel electrolyte prepared in Example 2 at 25 degrees Celsius and 2C current is shown. Figure 8 These are ionic conductivity graphs of the hydrogel electrolytes prepared in Examples 1 and 3 at different temperatures; Figure 9 These are freezing point diagrams of the hydrogel electrolytes prepared in Examples 1, 3, and 3; Figure 10 The cycling characteristics curves of the button cell assembled with the hydrogel electrolyte prepared in Comparative Example 1 at 25 degrees Celsius and 2C current are shown. Figure 11The curves show the cycling characteristics of a button cell assembled with the hydrogel electrolyte prepared in Comparative Example 2 at 25 degrees Celsius and 2C current. Detailed Implementation
[0044] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments.
[0045] All raw materials used in the embodiments are conventional and commercially available; unless otherwise specified, the methods described are existing technologies.
[0046] Example 1 A method for preparing a hydrogel electrolyte for a wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery includes the following steps: 1. Preparation of SA / PAM original hydrogel: Weigh 0.5 g of sodium alginate (SA) powder, dissolve it in 20 mL of deionized water, and stir for 2 hours until completely transparent to obtain the matrix solution.
[0047] Add 2.5 g of acrylamide (AM) monomer to the above solution and stir to dissolve.
[0048] Under ice bath conditions, the initiator ammonium persulfate (APS, 0.025 g), the crosslinking agent N,N'-methylenebisacrylamide (MBA, 0.0025 g), and the accelerator tetramethylethylenediamine (TEMED, 25 μL) were added sequentially.
[0049] After degassing, the mixture was poured into a glass mold and reacted in a 60°C oven for 6 hours to obtain a transparent, highly elastic SA / PAM pristine hydrogel. This was then cut into round pieces.
[0050] An interpenetrating network of sodium alginate (SA) and polyacrylamide (PAM) was formed in a pure water environment using free radical polymerization. This step was to avoid interference from organic solvents and high concentrations of salt in the polymerization reaction of acrylamide.
[0051] 2. Preparation of wide-temperature-range functional immersion solution (target electrolyte): Mixed solvent: Measure 30 mL of dimethyl sulfoxide (DMSO) and 70 mL of deionized water and mix thoroughly (DMSO volume fraction 30%).
[0052] Solute dissolution: Add zinc trifluoromethanesulfonate (Zn(OTf)2) to the mixed solvent to a concentration of 1 mol / L, lithium trifluoromethanesulfonate (LiOTf) to a concentration of 3 mol / L, and cerium chloride (CeCl3) to a concentration of 0.01 mol / L. Stir until the solution is clear and transparent.
[0053] 3. Solvent displacement: The cut SA / PAM original hydrogel discs were completely immersed in 50 mL of the above functional soaking solution.
[0054] The container is sealed and left to soak at room temperature for 6 hours, gently shaking it every 2 hours to accelerate diffusion equilibrium. At this point, the gel volume will slightly shrink but remain transparent. The gel is then removed to obtain the wide-temperature-range, long-life SA / PAM hydrogel electrolyte described in this invention.
[0055] 4. Battery assembly: As shown in Figure 1, a CR2032 button cell casing is used.
[0056] Positive electrode: Lithium manganese oxide (LiMn2O4), Super-p, and PVDF were added to NMP at a mass ratio of 7:2:1 and magnetically stirred for 6 hours. After being mixed evenly, the mixture was coated onto carbon cloth, dried, and sliced.
[0057] Negative electrode: Zinc foil is used.
[0058] Assembly: Place the spring sheet, gasket, zinc foil negative electrode sheet, the SA / PAM hydrogel electrolyte prepared above, and the positive electrode in sequence inside the negative electrode shell. Finally, cover with the positive electrode shell and seal with a sealing machine.
[0059] The diameter of the hydrogel electrolyte is significantly larger than that of the positive and negative electrode plates, which effectively prevents edge short circuits.
[0060] Figure 2 The figure shows the mechanical properties of the hydrogel electrolyte prepared in this embodiment at 25°C. As can be seen from the figure, the hydrogel electrolyte of this invention has good flexibility.
[0061] Figure 3 The figure shows the mechanical properties of the hydrogel electrolyte prepared in this embodiment after being placed at -20°C for 3 hours. As can be seen from the figure, the hydrogel electrolyte of this invention still has good flexibility under low temperature conditions.
[0062] Figure 4 The figure shows the cycle characteristics of the button cell assembled with the hydrogel electrolyte in this embodiment at 25 degrees Celsius and 2C current. As can be seen from the figure, the battery assembled with the electrolyte of this invention exhibits excellent cycle performance, maintaining stable operation after 1000 cycles with a capacity retention of 35.17%; the capacity retention is 99.45% after 100 cycles, 85.11% after 200 cycles, and 68.54% after 300 cycles. This is achieved without the addition of DMSO and cerium chloride (…). Figure 11The battery retained 72.45% of its capacity after 100 cycles, 61.35% after 200 cycles, and 54.43% after 300 cycles, but failed after more than 400 cycles. This demonstrates that the electrolyte assembly of this invention significantly improves cycle performance compared to batteries without DMSO and cerium chloride. Figure 5 The figures show the rate performance data of the button battery assembled with hydrogel electrolyte in this embodiment at different temperatures and 0.5C current. As can be seen from the figures, the button battery can still operate stably at low temperatures and has a certain capacity, which indicates that the battery has good temperature resistance and the capacity retention rate does not drop quickly at low temperatures, indicating good low-temperature performance; the battery capacity can reach 85.89mAh / g at -10°C and 0.5C.
[0063] Figure 6 This is a test diagram of the hydrogel electrolyte of this embodiment under repeated compression and deformation. As can be seen from the diagram, the hydrogel electrolyte of this invention has excellent mechanical properties. After repeated compression for 10,000 seconds, the hydrogel can still return to its original state.
[0064] Example 2 A method for preparing a wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery hydrogel electrolyte is described in Example 1, except that in step 2, 0.01 mol / L lanthanum chloride (LaCl3) is used instead of cerium chloride as the functional additive. Other steps and conditions are the same as in Example 1.
[0065] Due to La 3+ With Ce 3+ Similar ionic radii and lower reduction potentials also enable electrostatic shielding to suppress dendrites and enhance gel crosslinking. The assembled battery exhibits similar phenomena to cerium chloride. Figure 7 The figure shows the cycle characteristics of the button battery assembled with hydrogel electrolyte in this embodiment at 25 degrees Celsius and 2C current. As can be seen from the figure, the battery assembled with electrolyte of this invention has excellent cycle performance. The capacity retention rate is 90.38% after 100 cycles, 74.10% after 200 cycles, 64.49% after 300 cycles, and 44.26% after 1000 cycles. Example 3 A method for preparing a wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery hydrogel electrolyte is described in Example 1, except that in step 2, the mixing solvent is replaced as follows: 50 mL of dimethyl sulfoxide (DMSO) and 50 mL of deionized water are measured and mixed evenly (DMSO volume fraction 50%). Other steps and conditions are the same as in Example 1.
[0066] Technical Effects: While increasing the DMSO content does raise the electrolyte viscosity at room temperature, thus affecting ion migration rate and rate performance, its more significant effect lies in significantly reducing free water activity and disrupting the hydrogen bond network. This effectively suppresses low-temperature freezing and water decomposition side reactions, lowers the electrolyte's freezing point, and allows the hydrogel to maintain a soft and continuous ion transport channel at -50°C without freezing and whitening. Consequently, it significantly reduces interfacial impedance growth in extremely cold environments, broadens the electrochemical stability window, improves the uniformity of zinc anode deposition / stripping, and suppresses hydrogen evolution corrosion and dendrite risk. Ultimately, this results in more stable cycling performance and reliable output over a wide temperature range, making it suitable for energy storage applications in extreme environments such as polar or high-altitude exploration.
[0067] Figure 8 The figures show the ionic conductivity of the hydrogel electrolytes prepared in Examples 1 and 3 at different temperatures. It can be seen that the electrolyte of the present invention still has a high ionic conductivity at lower temperatures.
[0068] Figure 9 These are the freezing point data of the hydrogel electrolytes prepared in Examples 1, 3 and Comparative Example 3, showing that the electrolyte of the present invention has a low freezing point.
[0069] Comparative Example 1 A method for preparing a hydrogel electrolyte, as described in Example 1, except that the soaking solution in step 2 is replaced with a 2 mol / L zinc sulfate (ZnSO4) aqueous solution; In step 4 of battery assembly, the positive electrode is prepared as follows: polyaniline, Super-p, and PVDF are added to NMP in a mass ratio of 7:2:1 and then magnetically stirred for 6 hours. After being mixed evenly, the mixture is coated onto carbon cloth, dried, and sliced.
[0070] The other steps and conditions are the same as in Example 1.
[0071] Result comparison: Low temperature performance: At -10°C, the hydrogel electrolyte of Comparative Example 1 completely froze into a white ice block, and the battery capacity dropped to 0 at -10°C and 0.5C.
[0072] Cyclic performance: The cycle characteristics of the coin cell assembled with the hydrogel electrolyte in this comparative example at 25 degrees Celsius and 2C current are shown in the figure below. Figure 10 The capacity retention rate was 57.19% after 100 cycles and 39.49% after 200 cycles. After more than 200 cycles at room temperature, the battery failed due to short circuit caused by zinc dendrites piercing the gel. This demonstrates that batteries using zinc sulfate have short lifespans, rapid capacity decline, and the growth of zinc dendrites is not inhibited, highlighting the advantages of the electrolyte in this invention. Comparative Example 2 A method for preparing a hydrogel electrolyte, as described in Example 1, except that: the soaking solution in step 2 is replaced with a mixed aqueous solution of zinc trifluoromethanesulfonate (Zn(OTf)2) and lithium trifluoromethanesulfonate (LiOTf), wherein the concentration of zinc trifluoromethanesulfonate (Zn(OTf)2) is 1 mol / L and the concentration of lithium trifluoromethanesulfonate (LiOTf) is 3 mol / L; The other steps and conditions are the same as in Example 1.
[0073] The cycle characteristic curves of the coin cell assembled with the electrolyte prepared in this comparative example at 25 degrees Celsius and 2C current are shown in the figure below. Figure 11 As shown, the capacity retention rate is 72.45% after 100 cycles, 61.35% after 200 cycles, and 54.43% after 300 cycles. The battery fails after more than 400 cycles, further highlighting the advantages of the electrolyte of this invention. Comparative Example 3 A method for preparing a hydrogel electrolyte, as described in Example 1, except that: in step 2, DMSO in the mixed solvent is replaced with an equal amount of deionized water; other steps and conditions are the same as in Example 1.
[0074] Compared to Example 1, this hydrogel electrolyte lost its low-temperature performance, meaning it struggled to operate stably at low temperatures. At -30°C, the assembled button cell in this example completely failed, with its capacity dropping to 0 mAh / g; while the battery in Example 1 remained stable. However, compared to Comparative Example 2, this example incorporated functional additives, improving its cycle performance. Specifically, at 25°C and a 2C current, the capacity retention was 82.35% after 100 cycles and 54.61% after 400 cycles. It failed after 800 stable cycles, demonstrating a significant improvement in cycle performance.
[0075] Comparative Example 4 A method for preparing a hydrogel electrolyte, as described in Example 1, except that no functional additives are added; other steps and conditions are the same as in Example 1.
[0076] Compared to Example 1, this hydrogel electrolyte lost some of its cycling performance, with a faster decrease in capacity retention and a lower cycle life. The coin cell assembled in Example 1 could still operate stably after 1000 cycles, while the comparative example nearly failed around 1000 cycles, with a capacity retention of only 13.29% after 1000 cycles. Furthermore, its conductivity was lower than that of Example 1.
[0077] Compared to Comparative Example 2, this example added an organic solvent, which improved its low-temperature performance. Specifically, at -30°C, the button cell assembled in Comparative Example 2 completely failed, while the button cell assembled in this example could still operate stably at -30°C.
Claims
1. A wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery hydrogel electrolyte, characterized in that, It includes a polymer hydrogel framework and an electrolyte phase adsorbed and filled inside the framework; The polymer hydrogel framework is an interpenetrating double network structure formed by sodium alginate (SA) and polyacrylamide (PAM). The electrolyte phase includes a mixed solvent, an electrolyte salt, and functional additives; The mixed solvent is composed of water (H2O) and a co-solvent; the electrolyte salt is zinc trifluoromethanesulfonate (Zn(OTf)2) and lithium trifluoromethanesulfonate (LiOTf); and the functional additive is an alkali metal salt or a rare earth metal salt.
2. The wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery hydrogel electrolyte according to claim 1, characterized in that, The cosolvent is dimethyl sulfoxide (DMSO), ethylene glycol (EG), glycerol or acetonitrile, preferably dimethyl sulfoxide (DMSO).
3. The wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery hydrogel electrolyte according to claim 1, characterized in that, The volume percentage of the co-solvent in the mixed solvent is 20-60%, preferably 30-50%.
4. The wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery hydrogel electrolyte according to claim 1, characterized in that, The concentration of zinc trifluoromethanesulfonate (Zn(OTf)2) in the electrolyte phase is 0.5-2 mol / L, preferably 1 mol / L, and the concentration of lithium trifluoromethanesulfonate (LiOTf) is 2-4 mol / L, preferably 3 mol / L.
5. The wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery hydrogel electrolyte according to claim 1, characterized in that, In the functional additives, the rare earth metals are selected from one or more combinations of cerium (Ce), lanthanum (La), yttrium (Y), neodymium (Nd), europium (Eu), or gadolinium (Gd); the alkali metals are selected from one or two combinations of cesium (Cs) or rubidium (Rb); and the alkali metal salts or rare earth metal salts are selected from one or more combinations of chlorides, nitrates, or trifluoromethane sulfonates.
6. The wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery hydrogel electrolyte according to claim 5, characterized in that, The functional additives are cerium chloride (CeCl3) or lanthanum chloride.
7. The wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery hydrogel electrolyte according to claim 1, characterized in that, The concentration of the functional additive in the electrolyte phase is 0.001-0.1 mol / L, preferably 0.005-0.05 mol / L.
8. A method for preparing the hydrogel electrolyte for a wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery as described in any one of claims 1-7, comprising the steps of: (1) Acrylamide (AM), sodium alginate (SA), crosslinking agent N,N'-methylenebisacrylamide (MBA), initiator and accelerator were dissolved in deionized water and SA / PAM original hydrogel was prepared by free radical polymerization reaction; (2) The original SA / PAM hydrogel is immersed in an electrolyte phase containing mixed solvent, electrolyte salt and functional additives. After soaking treatment, the water inside the original SA / PAM hydrogel is completely replaced by the electrolyte phase using the concentration diffusion principle, so as to obtain a flexible zinc-lithium hybrid ion battery hydrogel electrolyte with a wide temperature range and long life.
9. The method for preparing the hydrogel electrolyte for a wide-temperature-range, long-life flexible zinc-lithium hybrid ion battery according to claim 8, characterized in that, Includes one or more of the following conditions: i. In step (1), the initiator is ammonium persulfate; the mass of the initiator is 1-5% of the mass of acrylamide, preferably 1%; ii. In step (1), the accelerator is tetramethylethylenediamine; the volume ratio of the accelerator to deionized water is 0.001-0.01:1; iii. In step (1), the mass ratio of acrylamide (AM), sodium alginate (SA), and crosslinking agent N,N'-methylenebisacrylamide (MBA) is 4-6:1:0.004-0.006, preferably 5:1:0.005; the mass ratio of acrylamide to deionized water is 0.1-0.3 g / mL. iv. In step (1), the free radical polymerization reaction temperature is 40-80℃ and the reaction time is 4-8h; a degassing step is also included before the free radical polymerization reaction; v. In step (2), the preparation method of the electrolyte phase is as follows: the electrolyte salt and functional additives are fully dispersed in a mixed solvent to obtain the electrolyte phase. vi. In step (2), the soaking temperature is room temperature, the soaking time is 4-8 hours, the soaking is carried out under static conditions, and the device is shaken every 2 hours to accelerate diffusion equilibrium.
10. The application of the hydrogel electrolyte according to any one of claims 1-7 in a flexible zinc-lithium hybrid ion battery; preferably, the flexible zinc-lithium hybrid ion battery includes a positive electrode, a negative electrode, and the hydrogel electrolyte located between the two; wherein, The positive electrode active material is lithium manganese oxide (LiMn2O4), and the negative electrode is zinc foil.