Carbonate-based electrolyte for indium-lithium bimetallic deposition-dissolution type reversible battery and preparation method thereof, and reversible battery

Abstract

The application relates to the technical field of lithium metal battery, in particular to a carbonate electrolyte for an indium-lithium bimetallic deposition-dissolution type reversible battery, a preparation method of the carbonate electrolyte and the reversible battery. The carbonate electrolyte comprises a lithium salt and an organic solvent, and the organic solvent comprises dimethyl carbonate and propylene carbonate; the concentration of the lithium salt in the electrolyte is 1-5 mol.L ‑1 -1; and the volume ratio of the dimethyl carbonate to the propylene carbonate is (7-9):(1-3). The application realizes the optimized balance of the electrolyte performance by mixing the dimethyl carbonate and the propylene carbonate in a specific volume ratio. As a low-viscosity solvent, the dimethyl carbonate effectively reduces the electrolyte viscosity and improves the ion migration rate; as a high-dielectric-constant solvent, the propylene carbonate enhances the dissociation capacity of the lithium salt and improves the ion conductivity. The proportioning ensures the high ion conductivity of the electrolyte and avoids the problems of excessive solventization of indium ions and intensified shuttle effect caused by the excessively high PC content.

Description

Technical Field

[0001] This invention relates to the field of lithium metal battery technology, and in particular to a carbonate electrolyte for indium-lithium bimetallic deposition-dissolution reversible battery, its preparation method, and the reversible battery. Background Technology

[0002] In the indium-lithium bimetallic battery system, metallic lithium is used as the negative electrode and metallic indium is used as the positive electrode. Indium has a standard electrode potential of -0.34 V, and when combined with lithium, it can provide an operating voltage of approximately 2.7 V, with a theoretical specific capacity of 210 mAh·g. - ¹. Indium exhibits good reversibility during electrochemical deposition and dissolution and is not prone to dendrite formation, making it a promising cathode material.

[0003] Traditional lithium-ion battery electrolytes have significant shortcomings when directly applied to indium-lithium systems, resulting in a severe indium ion shuttle effect. During charging, indium ions (In³⁺) exhibit a strong indium-lithium (In³⁺) shuttle effect. + Indium ions dissolve from the positive electrode into the electrolyte. If the electrolyte's solvation effect on indium ions is too strong, the indium ions can easily diffuse to the negative electrode side and undergo irreversible reduction, leading to loss of active material and capacity decay. This problem is particularly prominent when using electrolytes primarily composed of high dielectric constant solvents (such as propylene carbonate, PC).

[0004] Therefore, existing technologies still need further development and improvement. Summary of the Invention To address the aforementioned technical problems, this invention proposes a carbonate-based electrolyte for indium-lithium bimetallic deposition-dissolution reversible batteries, its preparation method, and an indium-lithium bimetallic deposition-dissolution reversible battery containing this electrolyte, thereby solving the problem of severe indium ion shuttlership in existing electrolytes in indium-lithium bimetallic batteries. Specifically: In a first aspect, a carbonate-based electrolyte for an indium-lithium bimetallic deposition-dissolution reversible battery, comprising: a lithium salt and an organic solvent, wherein the organic solvent comprises dimethyl carbonate and propylene carbonate; wherein the concentration of the lithium salt in the carbonate-based electrolyte is 1-5 mol·L⁻¹. -1 The volume ratio of the dimethyl carbonate to the propylene carbonate is (7-9):(1-3). The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0005] As a preferred technical solution, in the carbonate electrolyte, the volume ratio of dimethyl carbonate to propylene carbonate in the organic solvent is 7:3. As a preferred technical solution, in the carbonate electrolyte, the lithium salt is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, and lithium tetrafluoroborate; preferably, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide with a concentration of 1 mol·L⁻¹. -1 . As a preferred technical solution, the carbonate electrolyte further includes an additive in the organic solvent, wherein the additive is selected from one or more of ethylene carbonate, diethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, and vinylene carbonate. Secondly, a method for preparing the above-mentioned carbonate electrolyte, comprising the following steps: Dimethyl carbonate and propylene carbonate are mixed in the stated volume ratio to obtain a mixed solvent; The lithium salt is added to the mixed solvent and stirred until the lithium salt is completely dissolved. As a preferred technical solution, in the preparation method, the mixing and stirring processes are carried out under an inert atmosphere. Thirdly, an indium-lithium bimetallic deposition-dissolution reversible battery, comprising: The negative electrode is made of lithium metal. The positive electrode, wherein the material of the positive electrode includes indium metal; Electrolyte, wherein the electrolyte is the carbonate-based electrolyte described above; During charging, the indium-lithium bimetallic deposition-dissolution reversible battery strips indium metal on the positive electrode side to form indium ions; during discharging, indium ions in the electrolyte are deposited and reduced on the positive electrode side to form indium metal. As a preferred technical solution, the indium-lithium bimetallic deposition dissolution reversible battery further includes a separator disposed between the positive electrode and the negative electrode. The separator is a composite membrane of polyionic liquid and polypropylene, which is used to work with the electrolyte to suppress the shuttle diffusion of indium ions. As a preferred technical solution, the indium-lithium bimetallic deposition dissolution reversible battery wherein the positive electrode is composed of a self-supporting indium foil and the positive electrode does not contain binders or conductive additives. As a preferred technical solution, the indium-lithium bimetallic deposition dissolution reversible battery, wherein after charge-discharge cycles, the metallic indium on the positive electrode surface exhibits (221) crystal plane preferred orientation growth characteristics to reduce the nucleation barrier of lithium deposition.

[0006] Beneficial effects: Compared with existing technologies, this invention achieves an optimized balance of electrolyte performance by mixing dimethyl carbonate (DMC) and propylene carbonate (PC) at a specific volume ratio of (7-9):(1-3). DMC, as a low-viscosity solvent, effectively reduces the electrolyte viscosity and increases the ion migration rate; PC, as a high-dielectric-constant solvent, enhances the dissociation ability of lithium salts and improves ionic conductivity. This ratio ensures both high ionic conductivity (reaching 8-12 mS·cm) of the electrolyte and... -1 This approach avoids the problems of excessive indium ion solubilization and exacerbated shuttle effect caused by excessive PC content. The lithium salt concentration is controlled at 1-5 mol·L⁻¹. -1 Within this range, it provides sufficient lithium-ion concentration to support charging and discharging at high current densities, while avoiding the high viscosity and high cost issues associated with ultra-high concentration electrolytes. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 The diagram shows the properties of various solvent molecules in the embodiments of the present invention.

[0009] Figure 2 The indium ion valence state in the electrolyte of this embodiment of the invention after cyclic charging and discharging.

[0010] Figure 3 The Δm-ΔQ plot obtained by fitting the EQCM data.

[0011] Figure 4 This is a molecular dynamics simulation diagram of DMC and PC molecules participating in the construction of a solvated sheath layer of lithium ions and indium ions in an embodiment of the present invention.

[0012] Figure 5 This is a schematic diagram of the battery assembly in Embodiment 4 of the present invention. Figure 6 The electrolyte was prepared in Example 4 of this invention at 1 mA cm⁻¹ -2 0.1 mAh cm -2 and 1 mA cm -2 0.5 mAhcm -2 The electrochemical performance curves.

[0013] Figure 7 This is the SEM image of the positive electrode indium foil after cycling in Example 4.

[0014] Figure 8 The image shows the XRD pattern of the positive electrode indium foil after charging and discharging in Example 4.

[0015] Figure 9 The image shows the XRD pattern of the Li surface after charge-discharge cycles in Example 4.

[0016] Figure 10 This is a comparison of the charge-discharge curves of copper-lithium batteries and indium-lithium batteries under different rate conditions in Example 4.

[0017] Figure 11 Raman diagram of the electrolyte during charging of the copper-lithium and indium-lithium batteries in Example 4. Detailed Implementation

[0018] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0019] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0020] To address the severe indium ion shuttle problem present in existing electrolytes for indium-lithium bimetallic batteries, this invention provides a carbonate-based electrolyte for indium-lithium bimetallic deposition-dissolution reversible batteries, comprising: a lithium salt and an organic solvent, wherein the organic solvent includes dimethyl carbonate and propylene carbonate; wherein the concentration of the lithium salt in the electrolyte is 1-5 mol·L⁻¹. -1 The volume ratio of the dimethyl carbonate to the propylene carbonate is (7-9):(1-3).

[0021] Dimethyl carbonate (DMC) is a common low-viscosity organic solvent with a high dielectric constant and good lithium-ion conductivity. In the electrolyte, DMC mainly functions to dissolve lithium salts and provide a favorable ion-conducting environment, allowing lithium ions to maintain a high migration rate. Furthermore, DMC exhibits good electrochemical stability over a wide potential window, reducing side reactions in the electrolyte during charge and discharge processes, thereby improving the battery's coulombic efficiency.

[0022] Propylene carbonate (PC) is a cyclic organic solvent with a high dielectric constant and strong ability to dissolve lithium salts. The purpose of introducing PC into the electrolyte is that PC can participate in the formation of solvation structures for indium and lithium ions, effectively regulating the solvation layer of the ions. Specifically, the cyclic molecular structure of PC can more tightly encapsulate indium ions, increasing their solvation radius and thus increasing the migration resistance of indium ions in the electrolyte. This mechanism significantly reduces the migration rate of indium ions in the electrolyte, effectively suppressing the uncontrollable migration of indium ions to the negative electrode and solving the indium ion shuttle problem. At the same time, the solvation effect of PC on lithium ions is relatively weak, allowing lithium ions to maintain a high migration rate, thus not affecting the normal charge-discharge kinetics of the battery.

[0023] In this embodiment, dimethyl carbonate (DMC) and propylene carbonate (PC) are mixed at a specific volume ratio of (7-9):(1-3) to achieve an optimized balance of electrolyte performance. If the proportion of PC is too low, its regulatory effect on indium ion solvation is weakened, and the indium ion migration inhibition effect decreases; if the proportion of PC is too high, it will lead to an increase in the overall viscosity of the electrolyte, a decrease in ion conductivity, and is not conducive to the high-current charge-discharge performance of the battery. DMC, as a low-viscosity solvent, effectively reduces the electrolyte viscosity and improves the ion migration rate; PC, as a high dielectric constant solvent, enhances the dissociation ability of lithium salt and improves ionic conductivity. This ratio ensures both high ionic conductivity of the electrolyte (reaching 8-12 mS·cm) and good performance. -1 This also avoids the problems of excessive solvation of indium ions and exacerbation of the shuttle effect caused by excessive PC content.

[0024] The lithium salt concentration was controlled at 1-5 mol·L⁻¹ -1 Within this concentration range, the electrolyte provides sufficient lithium-ion concentration to support high current density charging and discharging while avoiding the high viscosity and high cost issues associated with ultra-high concentration electrolytes. Within this concentration range, the electrolyte exhibits moderate solubility for indium ions, meeting the requirements for indium deposition and dissolution reactions. Simultaneously, by regulating the solvation structure, the migration rate of indium ions is reduced, effectively suppressing the shuttle effect. Experimental data show that indium-lithium batteries using the electrolyte of this invention can reduce capacity loss due to indium ion shuttle by more than 60%.

[0025] In this embodiment, considering factors such as the binding ability of various molecules to indium ions, molecular orbital energy levels, electrolyte dielectric constant, and viscosity (as shown in Table 1), carbonate molecule DMC was selected as the main solvent (the properties of each molecule are as follows...). Figure 1 ), Figure 1The study systematically compared the performance of various electrolyte solvents (DME, DMC, DEC, EC, PCE, SCN, SL) in electrochemical systems. Solvent selection has a decisive impact on battery performance: EC and PCE solvents showed the best performance in terms of cycle stability (small voltage fluctuations and high cumulative efficiency) and capacity retention, while SCN and SL solvents suffered significant performance degradation due to their electronic characteristics (HOMO / LUMO energy level anomalies).

[0026] Energy parameters are highly correlated with experimental data: for example, the high HOMO level of SCN corresponds to its low accumulation efficiency. Based on all charts, solvent performance from best to worst is DMC > DME > DEC > SCN > SL.

[0027] Building upon this, adding a certain volume percentage of PC molecules, which have a lower HOMO energy level and higher stability, allows the battery to maintain its integrity for a longer period in the electrochemical environment, even when DMC molecules decompose to form an SEI film. This is beneficial for improving battery stability and extending cycle life. Furthermore, the SEI film formed by DMC decomposition can guide uniform lithium-ion deposition and inhibit dendrite growth on the lithium metal surface.

[0028] Table 1

[0029] The valence state changes of indium ions in the electrolyte and at the interface were characterized. The indium stripping valence state was calculated by the mass change of the indium foil before and after charge and discharge. The masses of the indium foil before and after charge and discharge were measured respectively. M 0 = 0.2687 , t = 0.1010 Based on the theoretical capacity and mass change, equations (1) and (2) are obtained. specific = applied / ( 0 t ) =(40 ) / (0.2687 0.1010 )=238.52 1 (1) ( → n n+ ) =1000nF / (3600 n ) =(1000×n×96485) / (3600×114.82)=238.52 1 (2) Combining the two equations, we get n=1. XPS testing of the indium ion valence state inside the electrolyte after charge-discharge cycles reveals a peak morphology of trivalent indium ions (e.g., Figure 2 This indicates that indium ions underwent a disproportionation reaction inside the battery, as shown in equation (3). 3In + 2In + In 3+ (3) The changes in the indium ion deposition process were characterized by electrochemical piezoelectric quartz crystal microbalance (EQCM) analysis, which is a technique that enables real-time study of the copper electrodeposition process. If the uniformly distributed deposition film on the substrate surface is rigid, the relationship between the mass change Δm (in g) and the frequency shift Δf (in Hz) during deposition and dissolution will satisfy the Sauerbrey equation. Combining the Sauerbrey equation (4) and Faraday's law (equation (5)), a quantitative relationship between the mass change and the amount of electricity (Q, in C) consumed during the electrode reaction can be obtained.

[0030] Δf = -2.264 × 10 -6 f o 2 Δm / A (4) Δm / M=Q / (nF)(5) Plotting Δm against Q, as follows Figure 3 As shown. The calculated theoretical value of M / n is 38.2 g / mol. Therefore, during deposition, trivalent indium is directly reduced to form indium metal. In general, during charging, indium is stripped off as monovalent to form monovalent indium ions, which then disproportionate inside the battery to produce trivalent indium ions and elemental indium. During discharging, trivalent indium ions are directly deposited to form indium metal.

[0031] DMC and PC molecules participate in the construction of the solvation sheath layer for lithium and indium ions, reducing the ion desolvation energy and promoting uniform ion deposition / dissolution. Molecular dynamics simulations show that... Figure 4 The addition of PC molecules weakens the coordination strength between indium ions and the solvent, thus accelerating interfacial mass transfer.

[0032] In this embodiment, the electrolyte forms a stable passivation layer on the surface of the indium cathode. This passivation layer is mainly composed of indium oxide and organic carbonate, which allows indium ion transport while inhibiting the continuous decomposition of the electrolyte. X-ray diffraction (XRD) analysis shows that the indium cathode using the electrolyte of this invention exhibits a preferred orientation of the (221) crystal plane after cycling. This orientation of the indium crystal plane has a lower surface energy and a higher atomic density, which is conducive to the uniform deposition of indium and reduces dendrite growth caused by local current density concentration. The electrolyte and the polyionic liquid-polypropylene composite separator work synergistically to further inhibit indium ion shuttle. The polyionic liquid layer has an electrostatic repulsion effect on indium ions while maintaining high transportability of lithium ions, realizing ion selective transport. Experimental results show that the indium-lithium battery using the electrolyte and composite separator of this invention retains more than 85% of its capacity after 500 cycles at 1 C rate, and the coulombic efficiency remains stable at over 98%.

[0033] In one implementation of this invention, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is used as the lithium salt. Compared to conventional lithium hexafluorophosphate, LiTFSI exhibits a wider electrochemical stability window (0-5 V), better thermal stability (decomposition temperature > 200°C), and lower aluminum corrosion resistance. The TFSI of LiTFSI... - Anions have a weak coordination ability and can form an SEI film rich in inorganic components (such as Li2O, Li3N, etc.) on the surface of metallic lithium. This SEI film has high mechanical strength and moderate ionic conductivity, which can effectively suppress the growth of lithium dendrites and improve the cycle stability and safety of the battery.

[0034] In this invention, the SEI film formed by the electrolyte has a bilayer structure. The inner layer (closer to the lithium anode) is mainly composed of inorganic components, including Li₂O, Li₃N, and LiF. These components originate from the decomposition of LiTFSI (TFSI). - →LiF + Li2SO3, etc.) and the reaction with trace amounts of moisture and oxygen. The inorganic components have high mechanical strength and chemical stability, which can effectively protect the lithium anode and suppress lithium dendrites. The outer layer (close to the electrolyte) is mainly composed of organic components, including ROC(O)OLi (from the reduction of carbonate) and ROSO2Li (from TFSI). - (Partial reduction), etc. The organic components have a certain degree of flexibility, which can adapt to the volume changes of the lithium anode.

[0035] This bilayer SEI film combines mechanical strength and flexibility, protecting the lithium anode from electrolyte corrosion while adapting to volume changes during charging and discharging, maintaining its integrity and preventing breakage and recombination. DMC and PC play a synergistic role in SEI film formation. Due to its high dielectric constant, PC easily accumulates on the lithium surface and is preferentially reduced to form the initial SEI film; DMC, by reducing electrolyte viscosity, promotes the transport of ions and solvent molecules, resulting in a more uniform and dense SEI film.

[0036] In one embodiment of the present invention, the organic solvent further includes an additive selected from ethylene carbonate, diethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, and vinylene carbonate.

[0037] In this embodiment, the main purpose of introducing additives is to further optimize the stability of the electrode interface and improve the coulombic efficiency of the battery. Taking FEC as an example, FEC can preferentially react on the surface of the lithium metal anode during electrochemical reduction to form a fluorine-containing solid electrolyte interphase (SEI) layer. This SEI layer has good chemical stability and ion conduction characteristics, which can effectively prevent direct contact between the electrolyte and lithium metal, reduce irreversible side reactions on the lithium metal surface, and thus improve coulombic efficiency. VC has a similar mechanism of action and can form a dense SEI layer on the anode surface, enhancing interface stability. EC, as a commonly used cyclic carbonate solvent, can further improve the dielectric constant of the electrolyte and the lithium salt solubility after addition. DEC and EMC, as linear carbonates, can reduce electrolyte viscosity and increase ion migration rate, which is beneficial to the high-current charge and discharge performance of the battery. Based on the same inventive concept, embodiments of the present invention also provide a method for preparing the carbonate electrolyte described above, comprising: mixing dimethyl carbonate and propylene carbonate in the volume ratio to obtain a mixed solvent; adding the lithium salt to the mixed solvent and stirring to completely dissolve the lithium salt. The electrolyte preparation process of this invention is simple, requiring only the dissolution of lithium salts by mixing solvents in a specific ratio, without the need for complex purification or modification steps, making it suitable for large-scale industrial production. All raw materials used are commercially available products, ensuring cost control and facilitating the practical application and promotion of indium-lithium bimetallic batteries. The electrolyte of this invention exhibits excellent electrochemical performance over a wide temperature range (-20℃ to 60℃). At low temperatures, the low melting point (-4.6℃) and low viscosity of DMC ensure the fluidity and ion transport capacity of the electrolyte; at high temperatures, the thermal stability of the electrolyte and its passivation effect on the electrodes suppress side reactions, maintaining stable battery operation.

[0038] Based on the same inventive concept, this invention also provides an indium-lithium bimetallic deposition-dissolution reversible battery, comprising: a negative electrode, a positive electrode, and an electrolyte. The negative electrode is made of metallic lithium; the positive electrode is made of metallic indium; and the electrolyte is the aforementioned carbonate-based electrolyte. During charging, indium ions are stripped from the metallic indium on the positive electrode side; during discharging, indium ions in the electrolyte are deposited and reduced on the positive electrode side to form metallic indium.

[0039] The indium-lithium bimetallic battery provided by this invention uses indium foil as the positive electrode, eliminating the need for binders and conductive agents, thus simplifying the electrode fabrication process, increasing the content of active materials, and enhancing the battery's energy density. The indium foil possesses excellent self-support and conductivity, enabling it to withstand volume changes during charging and discharging while maintaining the integrity of the electrode structure.

[0040] The following specific preparation examples will further explain the above-mentioned technical solutions provided by the present invention.

[0041] Example 1 An electrolyte was prepared by mixing 1 mmol of LiTFSI powder with 1 mL of DMC at room temperature. A battery was assembled using lithium foil as the negative electrode and indium foil as the positive electrode. The battery was tested at 0.25 mA cm⁻¹. -2 0.125 mAh cm -2 Under certain conditions, the cycle time can reach up to 500 hours.

[0042] Example 2 An electrolyte was prepared by mixing 6 mmol of LiTFSI powder with 2 mL of DMC at room temperature. A battery was assembled using lithium foil as the negative electrode and indium foil as the positive electrode. The battery was tested at 0.2 mA cm⁻¹. -2 0.1 mAh cm -2 Under certain conditions, the cycle time can reach up to 430 hours.

[0043] Example 3 An electrolyte was prepared by mixing 2 mmol of LiTFSI powder with 1.4 mL of DMC and 0.6 mL of EC at room temperature. A battery was assembled using lithium foil as the negative electrode and indium foil as the positive electrode. The battery was tested at 1 mA cm⁻¹. -2 0.1 mAh cm -2 Under certain conditions, the cycle time reaches up to 500 hours. Furthermore, the addition of additives significantly reduces battery polarization.

[0044] Example 4 At room temperature, 2 mmol of LiTFSI powder was added to 1.4 mL of DMC and 0.6 mL of PC to prepare an electrolyte. A battery was assembled using lithium foil as the negative electrode and indium foil as the positive electrode. Figure 5 As shown (the middle one is the separator, and the two on either side are the positive and negative electrodes). The battery operates at 1 mA cm⁻¹. -2 0.1 mAh cm -2 Cycle times up to 1000 hours under certain conditions. High-capacity 1 mA cm⁻¹ -2 0.5mAh cm -2 Under ideal cycling conditions, the battery cycle time reaches up to 520 hours. Adding the additive reduced battery polarization by 0.35 V. The electrolyte concentration at 1 mA / cm² is [not specified]. -2 0.1 mAh cm -2 and 1 mA cm -2 0.5 mAh cm -2 The electrochemical performance curves, such as Figure 6 As shown in the figure, this figure systematically illustrates the electrochemical behavior of the LiTFSI DMC:PC=7:3 electrolyte under different current densities and cycling conditions: 0.5 mA cm -2 At this level, voltage stability, capacity retention, and coulombic efficiency are all better than those at 0.1 mA cm⁻¹. -2 (Coulomb efficiency > 99.5%, voltage fluctuation < 0.2 V). 0.1 mA cm -2 Initially, the electrolyte exhibits poor performance (sharp voltage drop and low coulombic efficiency), but its stability improves over long-term cycling (coulombic efficiency stabilizes above 99%). With increasing cycle count (500–5000 cycles), the voltage plateau decreases and capacity decay intensifies, indicating performance degradation over long-term use. After 5000 cycles, the voltage plateau drops below 2.4 V, and capacity decay is significant.

[0045] To observe the deposition / stripping morphology of indium foil, SEM scans were performed on the indium foil after battery charging and discharging (e.g., ...). Figure 7 The study found that indium peeled off from an initial regular cubic shape to an irregular algal deposit during cycling. XRD analysis was performed on the indium foil after charge-discharge cycles (e.g., ...). Figure 8 Indium crystals exhibit a significant (221) plane-preferred orientation growth characteristic. This plane is typically a high surface energy plane, thermodynamically unstable, and strongly inclined to lower its surface energy by adsorbing other atoms. It has a high lithium affinity, and its moderate shuttle energy significantly reduces the nucleation barrier for lithium deposition, promoting lateral lithium diffusion and layered growth, thus kinetically preventing dendrite formation. Simultaneously, it participates in the formation of the lithium interface structure, facilitating smoother lithium-ion transport at the interface. This allows the battery to withstand higher current densities, i.e., better rate performance (fast charging capability). Figure 9 As shown, XRD analysis of Li after charge-discharge cycles revealed a significant characteristic peak of In. Compared to the same metal foil cathode (copper-lithium battery), the indium-lithium battery exhibits superior kinetic performance (e.g., ...). Figure 10 ), and test the electrolyte Raman spectroscopy (e.g.) after charging the battery. Figure 11 Copper ions have a stronger electrophilic ability and are more likely to bind to organic molecules. Copper binds strongly to organic molecules and anions, forming clusters with high coordination numbers. These clusters have greater resistance to migration, which is further evidence of the excellent kinetics of indium-lithium batteries.

[0046] Example 5 An electrolyte was prepared by mixing 2 mmol of LiTFSI powder with 1.8 mL of DMC and 0.2 mL of PC at room temperature. A battery was assembled using lithium foil as the negative electrode and indium foil as the positive electrode. The battery was tested at 1 mA cm⁻¹. -2 0.1 mAh cm -2 Under certain conditions, the cycle time can reach up to 600 hours.

[0047] Example 6 An electrolyte was prepared by mixing 2 mmol of LiTFSI powder with 1.2 mL of DMC and 0.8 mL of PC at room temperature. A battery was assembled using lithium foil as the negative electrode and indium foil as the positive electrode. The battery was tested at 1 mA cm⁻¹. -2 0.1 mAh cm -2 Under certain conditions, the cycle time can reach up to 700 hours.

[0048] Example 7 An electrolyte was prepared by mixing 10 mmol of LiFSI powder with 1.4 mL of DMC and 0.6 mL of PC at room temperature. A battery was assembled using lithium foil as the negative electrode and indium foil as the positive electrode. The battery was tested at 1 mA cm⁻¹. -2 0.1 mAh cm -2 Under the condition of 750 cycles.

[0049] Example 8 An electrolyte was prepared by mixing 2 mmol of LiPF6 powder with 1.4 mL of DMC and 0.6 mL of PC at room temperature. A battery was assembled using lithium foil as the negative electrode and indium foil as the positive electrode. The battery was tested at 1 mA cm⁻¹. -2 0.1 mAh cm -2 Under the condition of 500 cycles.

[0050] Example 9 An electrolyte was prepared at room temperature by mixing 2 mmol of LiTFSI and 0.2 mmol of LiI powder with 1.4 mL of DMC and 0.6 mL of PC. A battery was assembled using lithium foil as the negative electrode and indium foil as the positive electrode. The battery was tested at 1 mA cm⁻¹. -2 1 mAhcm -2 The cycle is repeated 400 times under the given conditions.

[0051] Comparative Example 1 This comparative example uses a conventional lithium-ion battery electrolyte: 1 M LiPF6 dissolved in an EC:DMC (1:1, v / v) mixed solvent. Preparation method: Mix 5 mL EC and 5 mL DMC, heat to 40°C to melt the EC, add 0.152 g LiPF6, stir until completely dissolved, and cool to room temperature. Since EC is solid at room temperature, the mixed solvent is viscous at room temperature.

[0052] Performance testing: Ionic conductivity is 8.5 mS·cm -1 (25℃). Viscosity: 3.5 mPa·s (25℃). Initial discharge specific capacity: 190 mAh·g. -1 After 500 cycles at 1 C rate, the capacity retention rate is only 65.3%, and the coulomb efficiency fluctuates between 95% and 97%.

[0053] Comparative Example 2 This comparative example uses pure PC as the solvent and 1 M LiTFSI as the lithium salt. Preparation method: Dissolve 0.287 g LiTFSI in 10 mL PC and stir until completely dissolved.

[0054] Performance testing: Ionic conductivity: 13.5 mS·cm -1 The viscosity (25℃) is the highest among all formulations, attributed to the high dielectric constant (64.92) of PC, which provides extremely strong lithium salt dissociation capability. Viscosity: 2.5 mPa·s (25℃). Initial discharge specific capacity: 193 mAh·g. -1 However, after 100 cycles at 1 C rate, the capacity decays to 120 mAh·g. -1 The capacity retention rate was only 62.2%, and the coulomb efficiency continued to decline during the cycle, reaching 92.5% at the 100th cycle.

[0055] Comparative Example 3 This comparative example uses pure DMC as the solvent and 1 M LiTFSI as the lithium salt. Preparation method: Dissolve 0.287 g LiTFSI in 10 mL of DMC and stir until completely dissolved. However, due to the very low dielectric constant of DMC (3.12), the dissolution rate of LiTFSI is slow, requiring approximately 2 hours of stirring to achieve complete dissolution.

[0056] Performance testing: Ionic conductivity: 5.2 mS·cm -1 The viscosity (25℃) is the lowest among all formulations, due to the low dielectric constant of DMC leading to low lithium salt dissociation. The viscosity is 0.9 mPa·s (25℃), the lowest. The initial discharge specific capacity is 185 mAh·g. -1 After 100 cycles at 1 C rate, the capacity retention rate is 72.5%, which is poor performance.

[0057] Comparative Example 4 This comparative example uses an ultra-high concentration electrolyte, with 10 M LiTFSI dissolved in a DMC:PC (7:3, v / v) mixed solvent.

[0058] Preparation method: Due to the extremely high lithium salt concentration, it is necessary to use a 60℃ water bath with continuous stirring for 4 hours to completely dissolve LiTFSI. The resulting electrolyte is slightly viscous.

[0059] Performance testing: Ionic conductivity: 6.5 mS·cm -1 The viscosity (at 25℃) is actually lower than that of medium-concentration electrolytes. This is because the extremely high concentration results in excessive viscosity, severely hindering ion migration. Viscosity: 12.5 mPa·s (25℃), the highest among all formulations. Initial discharge specific capacity is only 165 mAh·g. -1 This is due to severe polarization and kinetic limitations caused by high viscosity. However, it exhibits excellent cycling stability, with a capacity retention of 94.5% after 500 cycles at 1 C rate and a coulombic efficiency consistently above 99.5%.

[0060] Comparative Example 5 This comparative example uses a solvent ratio of DMC:PC = 5:5 (v / v), and 1 M LiTFSI is a lithium salt.

[0061] Preparation method: Mix 5 mL DMC and 5 mL PC, and dissolve 0.287 g LiTFSI.

[0062] Performance testing: Ionic conductivity: 12.0 mS·cm -1 (25℃), this is because the higher PC content provides stronger lithium salt dissociation capability. Viscosity: 2.3 mPa·s (25℃).

[0063] Initial discharge specific capacity: 194 mAh·g -1 After 500 cycles at 1 C rate, the capacity retention rate is 79.2%, and the coulombic efficiency is 95.5-97.8%.

[0064] Comparative Example 6 This comparative example uses a solvent ratio of DMC:PC = 9.5:0.5 (v / v), 1 M LiTFSI as a lithium salt, and the PC content is lower than the scope of the claims. Preparation method: Mix 9.5 mL DMC and 0.5 mL PC, and dissolve 0.287 g LiTFSI.

[0065] Performance testing: Ionic conductivity: 7.8 mS·cm -1 Viscosity: 1.2 mPa·s (25℃).

[0066] Initial discharge specific capacity: 191 mAh·g -1 After 500 cycles at 1 C rate, the capacity retention rate is 76.8%, and the coulombic efficiency is 96.5-98.0%.

[0067] Comparative Example 7 This comparative example does not contain PC; it uses only a mixed solvent of DMC and ethylene carbonate (EC) in a ratio of EC:DMC = 3:7 (v / v), with 1 M LiTFSI as the lithium salt. 3 mL of EC and 7 mL of DMC were mixed at 40°C to dissolve 0.287 g of LiTFSI, and the mixture was cooled to room temperature.

[0068] Performance testing: Ionic conductivity: 6.5 mS·cm -1 (25℃). Viscosity: 4.2 mPa·s (25℃). The overall viscosity is relatively high due to the high viscosity of EC (1.9 mPa·s). Initial discharge specific capacity: 189 mAh·g. -1 After 500 cycles at 1 C rate, the capacity retention rate is 75.5%.

[0069] Comparative Example 8 This comparative example uses an ionic liquid electrolyte: 1 M LiTFSI dissolved in 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ionic liquid. 0.287 g of LiTFSI was dissolved in 10 mL at 60 °C and stirred for 2 hours until completely dissolved.

[0070] Performance testing: Ionic conductivity: 3.5 mS·cm -1 (25℃), which is much lower than that of carbonate electrolytes.

[0071] Viscosity: 35 mPa·s (25℃). The extremely high viscosity severely limits ion transport.

[0072] The initial discharge specific capacity is only 145 mAh·g -1 The capacity utilization is severely limited. Cyclic stability is good, with a capacity retention rate of 91.5% after 500 cycles, but due to the low initial capacity, the absolute capacity is still not ideal.

[0073] The carbonate electrolyte and indium-lithium bimetallic battery provided by this invention have broad industrial application prospects, such as in the field of energy storage, where the energy density of the indium-lithium bimetallic battery can reach 400-500 Wh·kg. -1 Higher than traditional lithium-ion batteries (200-300 Wh·kg) -1 It is suitable for applications such as electric vehicles and drones that require high energy density.

[0074] The electrolyte of this invention maintains good performance over a wide temperature range (-20°C to 60°C), making it particularly suitable for use in extreme environments, such as electric vehicles and energy storage facilities in cold regions; industrial equipment in high-temperature environments; and applications in the aerospace field that require a wide temperature range.

[0075] Indium, as a soft metal, possesses excellent ductility and flexibility, making it suitable for fabricating flexible electrodes. Combined with the high-performance electrolyte of this invention, it holds promise for developing flexible indium-lithium batteries for applications in emerging fields such as wearable devices and flexible displays.

[0076] In summary, this invention proposes a carbonate-based electrolyte and a metal foil-type indium cathode system based on dimethyl carbonate / propylene carbonate (DMC / PC, 7:3 v / v) for use in indium-lithium bimetallic deposition-dissolution reversible batteries, resulting in batteries with excellent electrochemical performance. This method is simple to operate, low in cost, and suitable for large-scale commercial production.

[0077] This invention uses indium foil as the positive electrode material. Indium is relatively abundant in nature and its price is relatively stable. The preparation process of indium foil is mature and the cost is controllable. Compared with traditional positive electrode materials, indium foil does not require complex material synthesis and coating processes, significantly reducing manufacturing costs and process complexity. Furthermore, this invention solves the key technical challenge of indium ion shuttle by rationally designing the electrolyte composition, achieving stable cycling of the indium-lithium bimetallic system. This invention utilizes the solvation properties of DMC and PC with lithium salts during charge and discharge to promote uniform deposition of lithium and indium ions, thereby suppressing problems such as indium ion shuttle diffusion, enabling stable operation of the indium-lithium bimetallic deposition-dissolution reversible battery. This method is simple, easy to operate, highly efficient, and low-cost, meeting the needs of large-scale industrial production and commercial applications.

[0078] Finally, it should be noted that the above embodiments are only for illustrating the present invention and not for limiting the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and should be covered within the scope of the claims of the present invention.

Claims

1. A carbonate electrolyte for indium-lithium bimetallic deposition-dissolution reversible batteries, characterized in that, include: The electrolyte contains lithium salt and an organic solvent, wherein the organic solvent includes dimethyl carbonate and propylene carbonate; and the concentration of the lithium salt in the carbonate electrolyte is 1-5 mol·L⁻¹. -1 The volume ratio of the dimethyl carbonate to the propylene carbonate is (7-9):(1-3).

2. The carbonate electrolyte according to claim 1, characterized in that, The volume ratio of dimethyl carbonate to propylene carbonate in the organic solvent is 7-9:

3.

3. The carbonate electrolyte according to claim 1, characterized in that, The lithium salt is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, and lithium tetrafluoroborate; preferably, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide with a concentration of 1-3 mol·L⁻¹. -1 .

4. The carbonate electrolyte according to claim 1, characterized in that, The organic solvent also includes additives, which are selected from one or more of ethylene carbonate, diethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, and vinylene carbonate.

5. A method for preparing a carbonate-based electrolyte as described in any one of claims 1-4, characterized in that, Includes the following steps: Dimethyl carbonate and propylene carbonate are mixed in the stated volume ratio to obtain a mixed solvent; The lithium salt is dispersed in the mixed solvent to obtain the carbonate electrolyte.

6. The preparation method according to claim 5, characterized in that, The mixing and stirring process is carried out under an inert atmosphere.

7. An indium-lithium bimetallic deposition-dissolution reversible battery, characterized in that, include: The negative electrode is made of lithium metal. The positive electrode, wherein the material of the positive electrode includes indium metal; The electrolyte is a carbonate-based electrolyte according to any one of claims 1-4; During charging, the indium-lithium bimetallic deposition-dissolution reversible battery strips indium metal on the positive electrode side to form indium ions; during discharging, indium ions in the electrolyte are deposited and reduced on the positive electrode side to form indium metal.

8. The indium-lithium bimetallic deposition-dissolution reversible battery according to claim 7, characterized in that, It also includes a separator disposed between the positive electrode and the negative electrode, the separator being a composite membrane of polyionic liquid and polypropylene, used to work in conjunction with the electrolyte to suppress the shuttle diffusion of indium ions.

9. The indium-lithium bimetallic deposition-dissolution reversible battery according to claim 7, characterized in that, The positive electrode is composed of a self-supporting indium foil and contains no binder or conductive additive.

10. The indium-lithium bimetallic deposition-dissolution reversible battery according to claim 7, characterized in that, After charge-discharge cycles, the indium metal on the positive electrode surface of the battery exhibits (221) crystal plane preferred orientation growth characteristics to reduce the nucleation barrier of lithium deposition.

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