Aqueous sodium-ion battery high-voltage electrolyte with wide potential window
Patent Information
- Application Number
- CN202610977763.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-02
- Publication Date
- 2026-08-28
AI Technical Summary
但是，受限于水的热力学稳定窗口（约1.23 V），传统水系电解液难以支撑高电压体系，导致能量密度偏低，成为制约其性能提升的关键瓶颈
（1）本发明均三甲苯为添加剂，在电化学循环过程中，添加剂凭借其特定的分子构型与电子结构，能够定向吸附于电极材料表面，构建一层致密且稳定的疏水性物理吸附保护层，该吸附层能有效屏蔽活性位点，阻隔电解液中的水分子及氢氧根离子（OH-）与电极表面的直接接触，从而抑制水分子的氧化分解，提高电解液的析氧电位；通过界面吸附层的调控作用，减少界面副反应的发生，抑制电极材料的结构退化与溶解，扩宽电解液的电化学稳定窗口；
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Figure CN122659337A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a high-voltage electrolyte for aqueous sodium-ion batteries with a wide potential window, belonging to the field of aqueous sodium-ion battery technology. Background Technology
[0002] While sodium-ion batteries offer advantages such as abundant sodium resources, low cost, and electrochemical characteristics similar to lithium-ion batteries, mainstream non-aqueous sodium-ion batteries suffer from safety risks, low ionic conductivity, and complex manufacturing processes due to the flammable and toxic organic electrolytes they use. Aqueous sodium-ion batteries, using water as a solvent, fundamentally avoid the risks of combustion and explosion, and can be assembled without an inert atmosphere or dry environment, significantly reducing production costs and technological barriers. However, limited by the thermodynamic stability window of water (approximately 1.23 V), traditional aqueous electrolytes struggle to support high-voltage systems, resulting in lower energy density and becoming a key bottleneck restricting performance improvement. Summary of the Invention
[0003] To address the problem that traditional aqueous electrolytes struggle to support high-voltage systems, resulting in low energy density, this invention proposes a wide-potential-window aqueous sodium-ion battery high-voltage electrolyte. Through synergistic regulation with additives, the electrolyte effectively disrupts the hydrogen bond network structure between water molecules, suppressing hydrogen evolution and oxygen evolution side reactions. Simultaneously, the electrolyte components form an effective adsorption layer on the electrode surface, inhibiting electrode material dissolution and blocking interfacial side reactions. This invention significantly broadens the electrochemical stability window of the aqueous sodium-ion battery electrolyte, exhibiting high discharge specific capacity and excellent cycle stability.
[0004] A wide potential window aqueous sodium-ion battery high-voltage electrolyte, wherein the aqueous sodium-ion battery electrolyte is composed of additives mesitylene, sodium dodecyl sulfate and deionized water, and the concentration of sodium dodecyl sulfate in the high-voltage aqueous sodium-ion battery electrolyte is 0.1~2 mol / L.
[0005] Preferably, the volume fraction of the additive in the aqueous sodium-ion battery electrolyte is 7.5-50%.
[0006] Preferably, the aqueous sodium-ion battery electrolyte has an electrochemical stability window of 2.5~3.7V and an ionic conductivity of 10~100mS / cm.
[0007] The mechanism by which the aqueous sodium-ion battery electrolyte of this invention exhibits a wide potential window and high cycle stability is as follows: Due to van der Waals forces and C–H···π interactions between the hydrophobic long chain of sodium dodecyl sulfate and mesitylene molecules, they spontaneously adsorb and self-assemble on the titanium mesh electrode surface to form a dense hydrophobic organic interface phase. This interface phase prevents direct contact between water molecules and hydroxide ions (OH-) in the electrolyte and the electrode surface, thereby inhibiting the oxidative decomposition of water molecules, increasing the oxygen evolution potential of the electrolyte, and thus widening the electrochemical stability window to 3.61 V. When forming the Prussian blue cathode battery, the sulfate head group of sodium dodecyl sulfate generates a strong electrostatic anchoring effect with the iron sites on the electrode surface. The hydrophobic tail chain and mesitylene simultaneously coat the particle surface, preventing the dissolution of iron ions and ferricyanide ions, maintaining the integrity of the crystal structure, and thus ensuring highly reversible and stable capacity during charge-discharge cycles. Although the formation of the hydrophobic interface phase binds some free sodium ions and slightly reduces ionic conductivity, the abundant micelles in the electrolyte can rapidly replenish and dynamically repair defects when the interface film is damaged, maintaining a continuous ion transport pathway. This interface phase can isolate electrons, ensure the continuous transmembrane transport of sodium ions, and suppress excessive consumption of electrolyte and electrode materials by side reactions, thereby significantly improving electrochemical stability.
[0008] The beneficial effects of this invention are: (1) In this invention, succinate is used as an additive. During the electrochemical cycle, the additive, due to its specific molecular configuration and electronic structure, can be directionally adsorbed onto the surface of the electrode material to construct a dense and stable hydrophobic physical adsorption protective layer. This adsorption layer can effectively shield the active sites and block water molecules and hydroxide ions (OH-) in the electrolyte. - Direct contact with the electrode surface inhibits the oxidative decomposition of water molecules and increases the oxygen evolution potential of the electrolyte; through the regulatory effect of the interfacial adsorption layer, it reduces the occurrence of interfacial side reactions, inhibits the structural degradation and dissolution of electrode materials, and broadens the electrochemical stability window of the electrolyte. (2) The aqueous sodium-ion full battery electrolyte of the present invention forms a solid electrolyte interface layer during the cycling process, which improves the structural stability and electrochemical performance of the positive electrode material in the aqueous electrolyte, thereby enhancing the cycle efficiency of the aqueous sodium-ion battery, reducing the decay of the specific capacity of the aqueous sodium-ion battery, and is low in cost and simple to operate. Attached Figure Description
[0009] Figure 1 Linear sweep voltammetry curves of samples A1~A5 in Example 1 and the sodium-ion battery high-voltage electrolyte of Comparative Example 1 under a three-electrode system test condition of 1mV / S. Figure 2 Linear sweep voltammetric curves of sample A1 in Example 1 and sodium-ion battery high-voltage electrolyte in Comparative Example 2 under test conditions of 1 mV / S in a three-electrode system; Figure 3 This is a comparison chart of the conductivity and viscosity of the high-voltage electrolytes for sodium-ion batteries in samples A1~A5 of Example 1; Figure 4 The charge-discharge curves of sample A2 sodium-ion battery with different numbers of cycles were tested using the high-voltage electrolyte in Example 1. Figure 5 Charge-discharge curves of different numbers of cycles were tested with sodium-ion battery electrolyte for Comparative Example 1. Figure 6 The rate performance curves of sample A2 sodium ion battery electrolyte in Example 1 are tested at different current densities. Figure 7 The graph shows the charge-discharge efficiency and long-cycle comparison of the sodium-ion battery electrolytes tested in Example 1 (sample A2) and Comparative Example 1. Detailed Implementation
[0010] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.
[0011] Comparative Example 1: This comparative example used a 0.5 mol / L sodium dodecyl sulfate electrolyte and an iron-based Prussian blue composite material as the working electrode (the active material loading of the working electrode was 10.88 mg / cm³). 2 The graphite carbon electrode was used as the counter electrode, and saturated Ag / AgCl was used as the reference electrode. The electrode test potential range was -0.4 to 0.4 V, and the electrochemical stability window under the test condition of 1 mV / S was 2.67 V.
[0012] Comparative Example 2: This comparative example uses a 0.5 mol / L sodium sulfate electrolyte as the electrolyte, a titanium mesh as the working electrode, a graphite carbon electrode as the counter electrode, and saturated Ag / AgCl as the reference electrode. The electrode test potential range is -0.4 to 0.4 V, and the electrochemical stability window under the test condition of 1 mV / S is 1.9 V.
[0013] Example 1: A wide-potential-window aqueous sodium-ion battery high-voltage electrolyte, wherein the aqueous sodium-ion battery electrolyte is composed of the additive mesitylene, a soluble sodium salt (sodium dodecyl sulfate), and deionized water. The concentration of the soluble sodium salt (sodium dodecyl sulfate) in the high-voltage aqueous sodium-ion battery electrolyte is 0.5 mol / L, and the volume fractions of the additive (mesitylene) in the aqueous sodium-ion battery electrolyte are 7.5% (sample A1), 12.5% (sample A2), 17.5% (sample A3), 20% (sample A4), and 30% (sample A5), respectively. Using the high-pressure aqueous sodium-ion battery electrolyte of this embodiment as the electrolyte, Ag / AgCl as the reference electrode, a graphite rod as the counter electrode, and an iron-based Prussian blue composite material as the working electrode (the active material loading of the working electrode is 10.88 mg / cm³), 2 The assembled three-electrode system was tested at 1 mV / S; In this embodiment, the linear sweep voltammetry (LSV) curves of the aqueous sodium-ion battery electrolytes corresponding to Comparative Example 1 and samples A1~A5, measured under a three-electrode test system and a scan rate of 1 mV / s, are shown in Figure 1. From Figure 1, it can be seen that the electrochemical stability windows of the high-voltage aqueous sodium-ion battery electrolytes of Comparative Example 1 and samples A1, A2, A3, A4, and A5 in this embodiment are 2.67 V, 2.94 V, 3.61 V, 2.76 V, 3.09 V, and 2.79 V, respectively. V; Comparison of the test results of blank sample ST0 and optimal ratio sample A2 (ST12.5) shows that: long chain sodium dodecyl sulfate (SDS) and mesitylene can spontaneously adsorb and self-assemble on the carbon electrode surface to form a dense hydrophobic organic interface phase; this interface phase can significantly inhibit the occurrence of two types of side reactions, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), from a kinetic perspective; combined with LSV curves and accompanying table data, it can be clearly confirmed that: when using the optimal ratio ST12.5, the above-mentioned hydrophobic physical barrier can increase the oxygen evolution potential of the electrolyte to 3.06 V, while reducing the hydrogen evolution potential to -0.55 V, ultimately obtaining an ultra-wide electrochemical stability window with a width of 3.61 V; The linear sweep voltammetry curves of sample A2 and comparative example 2 sodium-ion battery electrolytes under the test condition of 1 mV / S in a three-electrode system are shown below. Figure 2 ,from Figure 2 It can be seen that the electrochemical stability window of sample A2 is significantly wider than that of Comparative Example 1 without added mesitylene and conventional aqueous sodium-ion battery electrolyte (0.5 mol / L Na2SO4, Comparative Example 2). Specifically, the electrochemical stability windows of Comparative Example 2 and Comparative Example 1 are 1.9 V and 2.67 V, respectively, while the window of sample A2 is 1.71 V and 0.94 V wider than the other two, respectively. This shows that the addition of mesitylene can effectively broaden the electrochemical stability window of aqueous sodium-ion electrolyte, suppress the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) side reactions of the electrolyte, and provide feasible conditions for achieving long-term cycle stability of aqueous sodium-ion batteries.
[0014] The conductivity and viscosity comparison chart of samples A1~A4 and Comparative Example 1 sodium-ion battery electrolyte in this embodiment is shown in the figure. Figure 3As shown in the figure, with the increase of the proportion of sodium dodecyl sulfate (SDS) and mesitylene, the bulk conductivity of the electrolyte shows a continuous upward trend, while the viscosity shows a significant downward trend. This is attributed to the fact that the additional sodium ions introduced by SDS effectively increase the carrier concentration in the system, while its hydrophobic alkyl chain and the benzene ring structure of mesitylene significantly reduce the fluid resistance of the electrolyte by disrupting the hydrogen bond network between water molecules. Combined with the analysis of the linear sweep voltammetry (LSV) test results, at the optimal ratio of ST12.5, the electrolyte also has a high bulk ion transport efficiency (conductivity of approximately 18 mS / cm). -1 With a viscosity of approximately 5.5 mPa·s and excellent interfacial hydrophobic film-forming properties, it achieves a synergistic effect between bulk mass transfer and interfacial stability. The charge-discharge curves of sample A2 sodium-ion battery electrolyte in this embodiment at different numbers of cycles are shown below. Figure 4 The charge-discharge curves of different numbers of cycles tested with the sodium-ion battery electrolyte in Comparative Example 1 are shown below. Figure 5 ,from Figures 4-5 As can be seen from the charge-discharge cycle curves of the blank sample ST0 and the optimal ratio ST12.5 in this embodiment shown in the attached figures, the blank control group without added sodium dodecyl sulfate (SDS) and mesitylene has an upper limit of battery operating voltage of only about 0.4 V, and the charge-discharge curve is sloping with significant polarization resistance. The specific capacity of the first cycle is only 47.56 mAh g. -1 By the third lap, the capacity had significantly decreased to 34.13 mAhg. -1 The battery using the ST12.5 optimal ratio successfully widened its actual charge / discharge voltage window to 1.0 V, exhibiting a flat sodium-ion insertion / extraction plateau, and significantly improved its specific capacity to 62.21 mAh g. -1 Furthermore, the charge-discharge curves of the first three cycles almost overlap. The rate performance curves of the A2 sodium-ion battery electrolyte in this embodiment under different current densities are shown in the figure. Figure 6 The charge-discharge efficiency and long-cycle comparison of the sodium-ion battery electrolytes of sample A2 and comparative example 1 in this embodiment are shown in the figure. Figure 7 ,from Figures 6-7 It can be seen that the sodium-ion battery electrolyte of the example sample A2 exhibits excellent rate performance and long-cycle stability in electrochemical tests; Figure 6 It can be seen that sample A2 at different current densities (0.1~0.5 A g) -1 The discharge specific capacity changes smoothly under different conditions, and when the current density recovers to 0.1 A g... -1 The specific capacity can quickly return to the initial level and remain stable, and the battery maintains a high coulombic efficiency of close to 100% throughout the rate test. Figure 7Further comparison of the long-cycle performance of sample A2 and comparative example 1 revealed that comparative example 1 (ST0) without added mesitylene experienced a precipitous capacity decay after 90 cycles, with a capacity retention rate of only 24.78%. In contrast, sample A2 (ST12.5) in this embodiment maintained a capacity retention rate of 84.21% after 150 long cycles, while achieving a cycle efficiency of 98.5%. These test results demonstrate that the electrolyte of this application, with the addition of 12.5% volume fraction mesitylene additive, not only significantly improves the rate reversibility of the battery but also effectively suppresses capacity decay during long cycles, showing a clear advantage over the comparative example system without the additive and exhibiting excellent cycle stability.
[0015] Example 2: A wide-potential-window aqueous sodium-ion battery high-voltage electrolyte, wherein the aqueous sodium-ion battery electrolyte is composed of the additive mesitylene, a soluble sodium salt (sodium dodecyl sulfate), and deionized water. The concentration of the soluble sodium salt (sodium dodecyl sulfate) in the high-voltage aqueous sodium-ion battery electrolyte is 1.0 mol / L, and the volume fractions of the additive (mesitylene) in the aqueous sodium-ion battery electrolyte are 7.5% (sample B1), 12.5% (sample B2), 17.5% (sample B3), 20% (sample B4), and 30% (sample B5), respectively. In this embodiment, the high-pressure aqueous sodium-ion battery electrolyte is used as the electrolyte, Ag / AgCl is used as the reference electrode, a graphite rod is used as the counter electrode, and an iron-based Prussian blue composite material is used as the working electrode (the active material loading of the working electrode is 6.233 mg / cm³). 2 The assembled three-electrode system was tested at 1 mV / S; In this embodiment, the linear sweep voltammetry (LSV) curves of the aqueous sodium-ion battery electrolytes corresponding to samples B1~B5 were measured under a three-electrode test system and a scan rate of 1 mV / s. The electrochemical stability windows of the high-voltage aqueous sodium-ion battery electrolytes of samples B1, B2, B3, B4, and B5 in this embodiment are 2.43 V, 2.69 V, 2.46 V, 2.21 V, and 2.08 V, respectively. The hydrogen evolution potentials corresponding to these embodiments are -0.435 V, -0.46 V, -0.40 V, -0.41 V, and -0.44 V, respectively; the oxygen evolution potentials corresponding to these embodiments are 1.98 V, 2.23 V, 2.06 V, 1.8 V, and 1.64 V, respectively; and the corresponding discharge specific capacities are 40.62 mAh g. -1 48.19 mAh g -1 25.78 mAh g -1 33.56 mAh g -1 28.63 mAh g -1Data shows that the system has a narrow overall window, with low overpotentials for both oxygen and hydrogen evolution. From a mechanistic perspective, the additives in this formulation failed to form a highly dense hydrophobic interface phase on the electrode surface, instead forming only a disordered and loose adsorption layer. This film layer has many defects, allowing water molecules to penetrate and contact the electrode active sites, which effectively suppresses the hydrogen and oxygen evolution side reactions kinetically, thus compressing the electrochemical stability window. The fluctuation in specific capacity also corroborates the continuous interference of the side reactions.
[0016] Example 3: A wide-potential-window aqueous sodium-ion battery high-voltage electrolyte, wherein the aqueous sodium-ion battery electrolyte is composed of the additive mesitylene, a soluble sodium salt (sodium dodecyl sulfate), and deionized water. The concentration of the soluble sodium salt (sodium dodecyl sulfate) in the high-voltage aqueous sodium-ion battery electrolyte is 0.1 mol / L, and the volume fractions of the additive (mesitylene) in the aqueous sodium-ion battery electrolyte are 7.5% (sample C1), 12.5% (sample C2), 17.5% (sample C3), 20% (sample C4), and 30% (sample C5), respectively. In this embodiment, a high-pressure aqueous sodium-ion battery electrolyte is used as the electrolyte, Ag / AgCl is used as the reference electrode, a graphite rod is used as the counter electrode, and an iron-based Prussian blue composite material is used as the working electrode (the active material loading of the working electrode is 8.771 mg / cm³). 2 The assembled three-electrode system was tested at 1 mV / S; In this embodiment, the linear sweep voltammetry (LSV) curves of the aqueous sodium-ion battery electrolytes corresponding to samples C1-C5 were measured under a three-electrode test system and a scan rate of 1 mV / s. The electrochemical stability windows of the high-voltage aqueous sodium-ion battery electrolytes of samples C1, C2, C3, C4, and C5 in this embodiment are 2.94 V, 3.15 V, 3.06 V, 2.73 V, and 2.60 V, respectively. The hydrogen evolution potentials corresponding to these embodiments are -0.61 V, -0.52 V, -0.50 V, -0.54 V, and -0.50 V, respectively; the oxygen evolution potentials corresponding to these embodiments are 2.33 V, 2.63 V, 2.56 V, 2.19 V, and 2.10 V, respectively; and the corresponding discharge specific capacities are 41.89 mAhg. -1 53.87 mAh g -1 43.23 mAh g -1 52.73 mAh g -1 43.63 mAh g -1It can be seen that this system has constructed a relatively ordered and dense hydrophobic interface phase compared to Example 2, which can effectively block water molecules, significantly improve the oxygen evolution and hydrogen evolution overpotentials, and widen the window to a maximum of 3.15 V, while also having a high discharge specific capacity. However, compared with the optimal sample A2 (3.61 V) in Example 1, its window is narrower by 0.46 V. Mechanistically, this interface phase still does not reach the level of the SEI-like film formed by the synergistic self-assembly of SDS long chains and mesitylene in Example 1 in terms of long-range order and density. This difference in microstructure directly determines that its ultimate suppression ability against water splitting side reactions at the limiting potential is not as good as that of Example 1.
[0017] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.
Claims
1. A wide-potential-window aqueous sodium-ion battery high-voltage electrolyte, characterized in that: The aqueous sodium-ion battery electrolyte is composed of additives mesitylene, sodium dodecyl sulfate and deionized water, and the concentration of sodium dodecyl sulfate in the high-voltage aqueous sodium-ion battery electrolyte is 0.1~2 mol / L.
2. The method for improving the high-voltage resistance of aqueous sodium-ion batteries according to claim 1, characterized in that: The volume fraction of the additive mesitylene in the aqueous sodium-ion battery electrolyte is 7.5-30%.
3. The method for improving the high-voltage resistance of aqueous sodium-ion batteries according to claim 1, characterized in that: The aqueous sodium-ion battery electrolyte has an electrochemical stability window of 2.5~3.7 V and an ionic conductivity of 10~100 mS / cm.