Enhanced Electrochemical Performance of Aqueous Zinc-Ion Batteries Using MnSO₄ Electrolyte Additive and α-MnO₂ Cathode

Abstract

Zinc-ion batteries (ZIBs) are an ideal choice for large-scale energy storage due to their high safety, environmental friendliness, and low cost. However, their performance is constrained by challenges related to cathode materials, such as poor conductivity, dissolution of active materials, and structural instability during cycling. In this study, α-MnO₂ cathode material with a tunnel structure was synthesized via a hydrothermal method, and MnSO₄ was introduced into the ZnSO₄ electrolyte to optimize the electrochemical performance of ZIBs. Characterizations through XRD, SEM, and BET revealed excellent crystal morphology and nanorod structures, which provided superior ion transport pathways. With the addition of MnSO₄, the discharge specific capacity of ZIBs at 0.1 A g⁻¹ was significantly improved from 172.9 mAh g⁻¹ to 263.2 mAh g⁻¹, the cycling stability was also notably enhanced, namely, after 1000 cycles with the current density of 1 mA cm⁻², the capacity settled at 50 mAh g⁻¹, which is a 47.4% increase in relation to the case of absent additive. The experimental results indicate that MnSO₄ additives effectively suppress manganese dissolution, improving the rate capability and reducing self-discharge. This study provides a novel approach to the development of high-performance aqueous zinc-ion batteries.

1. Introduction

The rapid development of portable electronic devices, electric vehicles, and renewable energy storage has placed higher demands on advanced energy storage technologies. Battery systems that are highly safe, cost-effective, environmentally friendly, and efficient have become a major focus of research [1,2,3,4]. Lithium-ion batteries have achieved significant advancements in energy density, power density, and cycle life. However, safety concerns stemming from flammable organic electrolytes, the limited availability of lithium resources, and price volatility have severely restricted their further use in large-scale energy storage applications [5,6]. As a result, developing energy storage systems based on aqueous electrolytes has become a vital alternative. Zinc-ion batteries (ZIBs) have attracted significant attention as a promising next-generation energy storage solution due to their low cost, high safety, environmental friendliness, and the abundant availability of zinc resources [7,8,9].

The positive electrode materials of ZIBs reported so far mainly include manganese-based oxides [10,11], vanadium-based oxides or vanadates [12,13], Prussian blue analogs [14], and layered transition metal dichalcogenides [15,16]. Although these materials have certain advantages in some aspects, they still have their own limitations. For example, the working voltage of vanadium-based compounds is low, which limits their energy density; Prussian blue analogs have low capacity and obvious aging problems; and layered transition metal dichalcogenides are prone to structural instability during repeated cycles, resulting in performance degradation [17,18]. In contrast, manganese-based oxides, especially MnO₂, have become one of the most concerned materials in ZIB research due to their good theoretical capacity, low cost, environmental friendliness, and relatively mature preparation process [19,20].

MnO₂ has a variety of crystal forms [21], including α-MnO₂, β-MnO₂, and δ-MnO₂. Its different crystal structures and zinc embedding mechanisms make it a research focus [22,23,24]. Among them, α-MnO₂ has become the most commonly used positive electrode material in insertion-type Zn-MnO₂ batteries due to its unique Zn²⁺/H⁺ insertion and extraction structure. However, despite the excellent theoretical performance of α-MnO₂, it still faces some challenges in practical applications [25]. First, the intrinsic low electronic conductivity of α-MnO₂ significantly limits its rate performance, especially at high current density, where the electrochemical reaction rate of the material cannot keep up with the rapid insertion/extraction of zinc ions, resulting in a significant decrease in discharge capacity. Secondly, during the charge and discharge process, α-MnO₂ may undergo phase change and volume expansion, which may lead to structural damage and capacity decay of the material, affecting the cycle stability of the battery. More seriously, Mn²⁺ dissolution is particularly prominent in manganese oxide-based cathode materials. This phenomenon not only causes the loss of active material but also severely deteriorates the long-term stability and cycling performance of the battery [26].

To overcome these problems, researchers have proposed a variety of optimization strategies, such as nano-sizing, doping, and composite material design, aiming to improve the conductivity, rate performance, and cycle stability of MnO₂ [27,28,29]. Although these methods have made some progress, the problems of manganese dissolution and phase change still exist and new solutions are urgently needed. Recent advances in hybrid energy storage systems and interfacial engineering strategies further highlight the importance of synergistic material design. For instance, innovative surface protection layers, such as tellurium nanobelt coatings on zinc anodes, have demonstrated remarkable suppression of dendrite growth and side reactions [30]. This approach underscores the critical role of interface optimization in balancing ion transport and structural stability—principles that can be extended to cathode material engineering. Building on these insights, studies have found that adding an appropriate amount of manganese ions (such as MnSO₄) to the electrolyte can effectively inhibit manganese dissolution and improve the battery’s cycle stability and capacity retention rate [31,32]. This strategy significantly improves the overall performance of the battery by optimizing the manganese ion concentration in the electrolyte and changing the reaction balance between the electrode and the electrolyte [33]. However, the influence mechanism of MnSO₄ on manganese-based oxide cathode materials has not been fully elucidated, and related research still needs to be further explored.

In this study, nanostructured α-MnO₂ cathode materials were synthesized via the hydrothermal method and characterized by XRD, SEM, and BET to analyze their crystal structure and morphology. The unique 2 × 2 tunnel structure (4.6 Å × 4.6 Å) of nanorod-like α-MnO₂ provides efficient pathways for Zn²⁺/H⁺ co-insertion, enhancing ion transport during battery operation. To further improve electrochemical performance, MnSO₄ was introduced as an electrolyte additive, effectively suppressing Mn²⁺ dissolution and optimizing the electrode–electrolyte interface. The impact of this modification on zinc-ion battery performance was evaluated by analyzing key indicators such as discharge-specific capacity, cycle retention rate, and rate capability. This study not only offers a new strategy for enhancing the performance of manganese-based oxide cathode materials but also provides theoretical and practical guidance for the industrial application of aqueous zinc-ion batteries. This study is limited to pure α-MnO₂ only, but one should have in mind that other strategies (for instance composite coatings over α-MnO₂ [29], or the use of layered MnO₂ structure [31]) may provide very competitive both coulombic capacities and capacity stability on long cycling.

2. Experimental Section

2.1. Materials Synthesis

All chemical reagents were analytically pure and no further purification was required. The synthesis of α-MnO₂ nanorods was carried out using a modified hydrothermal method based on previous reports [25,34]. In a typical procedure, 0.474 g KMnO₄ (battery grade, China National Pharmaceutical Group Corporation, Beijing, China) was dissolved in 60 mL deionized water and stirred for 10 min. Then, 1 mL hydrochloric acid (1 mol/L HCl, China National Pharmaceutical Group Corporation, Beijing, China) was slowly added to the solution. After stirring for 30 min, the mixture was transferred into a 100 mL polytetrafluoroethylene-lined hydrothermal autoclave and heated at 160 °C for 12 h. The resulting product was cooled to room temperature, filtered, washed with deionized water, and dried at 60 °C for 12 h to obtain α-MnO₂ nanorods. This method was optimized to achieve a uniform nanorod morphology with a 2 × 2 tunnel structure, which is crucial for efficient Zn²⁺/H⁺ co-insertion [25]. The term “tunnel structure” refers to the specific arrangement of MnO₆ octahedra in α-MnO₂, forming interconnected channels that facilitate ion transport. In α-MnO₂, the MnO₆ octahedra share edges and corners, creating a well-defined 2 × 2 tunnel structure with a diameter of approximately 4.6 Å × 4.6 Å. This tunnel configuration allows for the efficient insertion and extraction of Zn²⁺ and H⁺ ions during battery operation, contributing to the material’s high electrochemical performance. The specific reaction is shown in the following formula:

$$\mathrm{KMn}{\mathrm{O}}_4+{\mathrm{H}}_2\mathrm{O}+\mathrm{HCl}\to {\mathrm{MnO}}_2·{\mathrm{H}}_2\mathrm{O}+\mathrm{KCl}+{\mathrm{H}}_2\mathrm{O}\hspace{1em}\mathsf{\Delta }\mathrm{G}<0$$

(1)

The working electrode was prepared by mixing 80 wt% positive active material, 10 wt% conductive carbon black (Super-P, battery grade, Shenzhen Kejing Star Technology Co., Ltd., Shenzhen, China), and 10 wt% polytetrafluoroethylene (PTFE, battery grade, Shenzhen Kejing Star Technology Co., Ltd., Shenzhen, China). Anhydrous ethanol was used as the solvent. The slurry was uniformly coated onto a stainless-steel foil current collector, ultrasonically mixed, and dried at 60 °C in a vacuum oven for 2 h. The circular electrode with a diameter of 10 mm was cut, and the electrode mass was fixed to 2 mg cm⁻². A glass-fiber separator (Whatman, battery grade, Maidstone, UK) was used during the assembly process.

A metal zinc sheet was used as the negative electrode. Prior to assembly, the zinc sheets were mechanically polished with 2000-grit sandpaper to remove surface oxides and impurities, ensuring a clean electrochemical interface. Glass fiber was used as the diaphragm, and 2 M ZnSO₄ or 2 M ZnSO₄ + 0.2 M MnSO₄ was used as the electrolyte. The coin cells (CR 2032) were sealed by a hydraulic crimping machine to finalize their assembly (MTI, MSK-110). The specific preparation process of electrode materials is shown in Figure 1.

2.2. Material Characterization

The crystal structure was determined by X-ray diffractometer (D8 Advance, BRUKERAXSGMBH, Karlsruhe, Germany) using CuKα1 at a wavelength of 0.15406d° nm and 2θ in the range of 5–80°. The microstructure of the samples was examined using a scanning electron microscope (SEM, SU8010, Tokyo, Japan). The Brunauer–Emmett–Teller surface areas were examined using a physisorption analyzer (Autosorb iQ, Quantachrome Instruments, Boynton Beach, FL, USA), and the pore size distribution was determined using a Barrett–Joyner–Halenda (BJH) module.

2.3. Electrochemical Measurements

An electrochemical workstation (CHI660E, Shanghai Chenhua Company, Shanghai, China) was used to carry out 1000 cycles of charge and discharge cycle tests at a current density of 1 A g⁻¹; rate charge and discharge tests were carried out at different rates of 0.1 A g⁻¹, 0.2 A g⁻¹, 0.5 A g⁻¹, 1 A g⁻¹ and 2 A g⁻¹; cyclic voltammetry tests were carried out using different scan rate tests, the voltage test range was 0.9~1.8 V, and the test temperature was 25 °C.

3. Results and Discussion

3.1. Characterization

Figure 2 shows the XRD spectrum of the α-MnO₂ cathode material. It can be seen from the figure that the sample has obvious diffraction peaks at 2θ = 12.78°, 18.10°, 25.71°, 28.84°, 37.52°, 41.96°, 49.86°, 56.37°, 60.27°, 65.1°, 69.71°, and 72.71°, which correspond to the (110), (200), (220), (310), (211), (301), (411), (600), (521), (002), (541), and (312) crystal planes, respectively. The intensity and position of the diffraction peaks are in good agreement with the standard α-MnO₂ spectrum of JCPDS card number 44-0141, indicating that pure phase α-MnO₂ was successfully synthesized without the presence of impurities. These strong diffraction peaks reflect the good crystallinity of the material. The tunnel structure of α-MnO₂ forms a double chain through the corner sharing of MnO₆ octahedron, forming a tunnel with a cross-section of 2 × 2 (4.6 Å × 4.6 Å). This tunnel size is conducive to the embedding of cations and the stability of the crystal structure, thus giving the material a higher specific capacity [34].

In order to observe the morphology of the sample, Figure 3a,b are SEM images of α-MnO₂ at different magnifications. According to Figure 3a,b, α-MnO₂ has a uniformly distributed nanorod structure, a smooth surface, and a clear angular structure, indicating that the sample has a good crystal morphology. In addition, the nanowires present a hollow structure, which is conducive to the full contact between the positive electrode active material and the electrolyte solution, making it easier for the electrolyte to penetrate into the electrode material, shortening the diffusion path of protons and zinc ions, and thus improving the electrochemical performance of the α-MnO₂ positive electrode material.

Figure 3c shows the nitrogen adsorption–desorption isotherm, which shows that the sample has a typical type IV isotherm characteristic (according to IUPAC classification), accompanied by a significant H3 type hysteresis loop, indicating that the interior of the sample is mainly a mesoporous structure [35]. The BET-specific surface area is 18.265 m²/g, which shows that the material has a large surface area and can provide more active sites for electrochemical reactions. The total pore volume of the sample is 0.075 cm³/g and the average pore size is 3.258 nm, which further verifies that its main pore size is in the mesoporous range (2–50 nm). The pore size distribution curve in the inset is obtained by BJH analysis, showing that the pore size distribution is concentrated in the range of less than 20 nm. This pore structure characteristic can significantly improve the permeability and mass transfer efficiency of the electrolyte, while increasing the electrochemical reaction interface, which helps to optimize the performance of α-MnO₂ in energy storage devices [36].

The mesoporous structure of the α-MnO₂ material, with a pore size distribution concentrated in the range of less than 20 nm, is particularly advantageous for the diffusion of Zn²⁺ and Mn²⁺ ions. The smaller pores within this range provide a large surface area and short diffusion pathways, which facilitate the rapid insertion/extraction of ions during the electrochemical process. While the current pore structure is well-suited for ion transport, further optimization of the pore size distribution (e.g., targeting 2–10 nm pores) could be explored in future work to enhance the diffusion kinetics of Zn²⁺ ions specifically.

3.2. Electrochemical Testing of MnO₂-Based Cathode Materials

3.2.1. Cyclic Voltammetry

As can be seen from Figure 4a, the CV curve of the α-MnO₂ sample at a scan rate of 0.5 mV s⁻¹, a voltage range of 0.9~1.8 V, and 2 M ZnSO₄ shows two reduction peaks at 1.25 V and 1.4 V, corresponding to the process of Zn²⁺ embedding into the α-MnO₂ lattice structure, accompanied by the reduction in Mn(IV) in α-MnO₂ to Mn(III). An oxidation peak and a shoulder peak appear near 1.55 V and 1.6 V, respectively, corresponding to the process of Zn²⁺ escaping from the α-MnO₂ structure, during which Mn(III) is oxidized to Mn(IV). The two clear pairs of redox peaks in the curve indicate that multi-step redox reactions occurred during the charge and discharge process. The gradual change in CV area during initial cycles is primarily attributed to the electrode activation process, which involves the stabilization of the electrode–electrolyte interface and optimization of ion transport pathways. Similar phenomena have been widely reported for Mn-based oxide cathodes [28,34]. In addition, the gradual stabilization of the curve shape indicates that the material has undergone electrode activation and achieved good stability.

Figure 4b shows the comparison of the CV behavior of the α-MnO₂ electrode in two different electrolytes (2 M ZnSO₄ and 2 M ZnSO₄ + 0.2 M MnSO₄). From the curve comparison, it can be seen that the redox peak positions and overall CV curve shape remain largely unchanged after the addition of MnSO₄, indicating that MnSO₄ does not significantly alter the intrinsic redox reactions of the electrode material. However, the increased potential window suggests that Mn²⁺ ions participate in the electrochemical process, potentially stabilizing the electrode/electrolyte interface and improving charge transfer dynamics. Additionally, Mn²⁺ may help regulate the deposition/dissolution equilibrium of MnO₂, mitigating polarization effects and enhancing electrochemical reversibility. These findings confirm that α-MnO₂ exhibits excellent structural stability and electrochemical performance in MnSO₄-containing electrolytes, further demonstrating its potential as a promising cathode material for zinc-ion batteries.

3.2.2. Ratio Test

Figure 5 shows the battery rate performance comparison curves of α-MnO₂ samples under different electrolyte conditions, and analyzes in detail the significant effect of Mn²⁺ addition on the performance of zinc-ion batteries. Experiments show that the discharge-specific capacity of the α-MnO₂ electrode at current densities of 0.1, 0.2, 0.5, 1, and 2 A g⁻¹ are 172.9, 139.1, 87.3, 56.3 and 37.0 mAh g⁻¹, respectively. After cycling at a high current density (2 A g⁻¹), when the current density is restored to 0.1 A g⁻¹, the discharge-specific capacity can be restored to 150.0 mAh g⁻¹, accounting for 86.8% of the initial capacity, showing a good rate capability, performance, and cycle stability. When Mn²⁺ is pre-added to the ZnSO₄ electrolyte, the rate performance of the zinc-ion battery is further improved. In the electrolyte containing Mn²⁺, the discharge-specific capacity of the α-MnO₂ electrode at the same current density reached 263.2, 232.6, 184.2, 135.7, and 96.5 mAh g⁻¹, respectively, with a rate of 36.7%. After high-rate cycling, when the current density is restored to 0.1 A g⁻¹, the reversible specific capacity can be restored to 259.0 mAh g⁻¹, which is significantly higher than that of the system without Mn²⁺ addition, showing excellent reversibility and higher capacity utilization.

This phenomenon can be attributed to the fact that the addition of Mn²⁺ significantly improves the active material utilization of the electrode material and inhibits the dissolution behavior of Mn²⁺ from the positive electrode material. The Mn²⁺ in MnSO₄ effectively reverses the dynamic equilibrium of Mn²⁺ dissolving from the α-MnO₂ cathode into the electrolyte by regulating the dissolution–deposition equilibrium, thereby reducing the loss of active substances. In addition, the reversible insertion/extraction process of Mn²⁺ alleviates the lattice stress caused by the insertion/extraction of Zn²⁺ to a certain extent, further improving the structural stability and kinetic properties of the electrode material. This mechanism not only prolongs the cycle life of the battery, but also significantly improves the rate performance of the battery, providing an effective strategy for optimizing the electrochemical performance of zinc-ion batteries.

3.2.3. Self-Discharge Performance

Figure 6 shows the comparison of the self-discharge performance of α-MnO₂ samples in different electrolytes. As shown in Figure 6a, the voltage of the battery using ZnSO₄ electrolyte dropped significantly after standing for 24 h, and the Coulombic efficiency was only 79.6%. This indicates that, in pure ZnSO₄ electrolyte, the battery has a higher self-discharge rate, which may be caused by side reactions in the solution or spontaneous reactions of the active materials. In contrast, Figure 6b shows the self-discharge performance of the cell assembled in a mixed electrolyte of ZnSO₄ and MnSO₄. The results showed that during the 24 h static period, the battery’s voltage remained relatively stable and the Coulombic efficiency increased significantly to 98.6%. This result indicates that the addition of MnSO₄ significantly reduces the self-discharge rate of the battery, which may be achieved by stabilizing the electrode surface reaction or exerting the synergistic effect of manganese ions in the solution. This effect effectively suppresses the unfavorable self-discharge process and significantly improves the electrochemical stability of the battery.

3.2.4. Cycle Performance

Figure 7 shows the constant current charge and discharge test of the α-MnO₂ sample in the voltage range of 0.9~1.8 V and a current density of 1 A g⁻¹. As can be seen from Figure 7, the battery using the mixed electrolyte (ZnSO₄ + MnSO₄) exhibits a higher discharge-specific capacity in the initial stage, which has a significant advantage over the battery using the pure ZnSO₄ electrolyte. In the early stage of the cycle, the specific capacity of the pure ZnSO₄ electrolyte system decreases rapidly, while the capacity decay of the mixed electrolyte system is relatively gradual. After 1000 cycles, the battery capacity retention rates of pure ZnSO₄ electrolyte and mixed electrolyte are 36.2% and 47.4%, respectively. In addition, the Coulombic efficiency of all systems remains above 98% during the entire cycle, indicating the high reversibility of α-MnO₂ materials.

This performance difference can be attributed to the effect of electrolyte composition on the structural stability of electrode materials. In pure ZnSO₄ electrolyte, part of the manganese in the electrode material α-MnO₂ undergoes a dissolution reaction, resulting in a high concentration of Mn²⁺ in the electrolyte, leading to loss of active substances and accelerated capacity decay. In the mixed electrolyte, the pre-introduction of Mn²⁺ can change the chemical equilibrium of the manganese dissolution reaction in the electrode material, significantly inhibit the manganese dissolution process, inhibit capacity decay, and stabilize the electrode material.

3.3. Application

Figure 8 shows the excellent performance of zinc-ion batteries based on α-MnO₂ in practical power supply applications. In this experiment, a single ZIB (1.8 V) requires approximately 3 h to reach full charge at a current density of 0.1 A g⁻¹. When three ZIBs are connected in series (total voltage = 1.8 V × 3 = 5.4 V), the total charging time extends to approximately 9 h under the same conditions. As shown in Figure 8a, the assembled zinc-ion battery achieves a stable discharge process by connecting an electronic timer, and can continuously and stably provide power for up to 23 h and 59 min, indicating its excellent power supply capacity and long-term power support performance.

To evaluate its real-world applicability, as shown in Figure 8b, the fully charged ZIB system was used to charge a smartphone with a nominal lithium-ion battery (LIB) capacity of 3000 mAh. The effective capacity of the ZIB system is determined by the single-cell capacity (263.2 mAh g⁻¹, active material loading: 2 mg cm⁻²). In a series circuit, while the voltage increases, the total capacity remains equal to that of a single cell, following the fundamental principle of battery module design. These results confirm that ZIBs can serve as a feasible power source for portable electronic devices. Future work will focus on further optimizing energy density and cycle life to enhance the practical performance of ZIBs in consumer electronics applications.

This excellent performance is mainly due to the high specific capacity, excellent cycle stability, and discharge performance of the α-MnO₂ positive electrode material. The unique tunnel structure and rich redox active sites of α-MnO₂ can promote the efficient insertion and deintercalation of Zn²⁺ ions and provide stable energy output. In addition, its chemical stability in aqueous electrolytes further enhances the practical application capabilities of the battery. Zinc-ion batteries based on α-MnO₂ show their great potential in powering portable electronic devices, providing a new research direction for the development of low-cost, high-safety, and high-performance energy storage devices.

Table 1. Comparison of electrochemical performance.

Material	Current Density (A g−1)	Specific Capacity (mAh g−1)	References
δ-MnO2	0.1	126	[37]
Ocu-Mn2O3	0.1	241	[38]
C-Mn2O3	0.1	167	[39]
ZnMn2O4	0.1	168	[40]
Mn3O4/GO	0.1	215.6	[41]
α-MnO2	0.1	263.2	This work

shows the comparative data of the specific capacity of different manganese oxide materials at a current density of 0.1 A g⁻¹. As can be seen from the table, the zinc ion battery based on α-MnO₂ exhibits the highest specific capacity, 263.2 mAh g⁻¹, far exceeding the specific capacity of other reported materials.

The excellent electrochemical performance of α-MnO₂ is due to its unique tunnel structure and abundant efficient redox active sites, which promote the insertion and deinsertion process of Zn²⁺, thus significantly improving its energy storage capacity. Compared with other manganese oxide materials, α-MnO₂ not only shows a higher specific capacity, but also shows its great potential in practical applications.

4. Conclusions

This study synthesized α-MnO₂ nanorod cathode materials with tunnel structures by hydrothermal method and systematically explored the effect of MnSO₄ additives on the performance of aqueous zinc-ion batteries, and the following conclusions were drawn:

• The α-MnO₂ cathode material with a 2 × 2 tunnel structure (4.6 Å × 4.6 Å) was successfully synthesized using a modified hydrothermal method based on previous reports. XRD, SEM, and BET characterizations revealed a highly crystalline structure, uniform nanorod morphology, and rich mesoporous characteristics, which provide more active sites and excellent channels for ion transport and electrochemical reactions. The optimized synthesis conditions ensured the formation of a stable tunnel structure, which is critical for the high performance of the material;
• Electrochemical results show that the MnSO₄-modified electrolyte increases the discharge capacity of the α-MnO₂ cathode at 0.1 A g⁻¹ from 172.9 mAh g⁻¹ to 263.2 mAh g⁻¹ (an increase of 52.2%); the capacity retention rate of the system containing the MnSO₄ electrolyte reaches 47.4% after 1000 cycles, which is significantly improved compared with the pure ZnSO₄ system (36.2%); the MnSO₄ additive increases the coulombic efficiency of the battery from 79.6% to 98.6% after standing for 24 h. At the same time, the introduction of MnSO4 effectively inhibits the dissolution of manganese in α-MnO₂, optimizes the dissolution–deposition balance, and improves the rate performance and self-discharge performance;
• The zinc-ion battery based on α-MnO₂ exhibits excellent power supply performance in practical applications, which verifies the practical application potential of zinc-ion batteries in powering portable electronic devices.

To further elucidate the capacity fade mechanism, future work will include post-cycling characterization of the active material (e.g., SEM, XRD, XPS) to detect structural changes, Mn²⁺ dissolution, and side reaction products. These analyses will provide deeper insights into the degradation processes and guide the design of more stable cathode materials.

This study provides an effective strategy for improving the performance of zinc-ion batteries through electrolyte optimization and lays a theoretical foundation and practical support for the development of low-cost, high-performance energy storage devices.