宽电化学窗口水系电解质与相关高能钠离子电池研究

低成本和高安全的水系钠离子电池有望用于大规模储能，提高其能量密度可进一步降低使用成本并拓展应用范围。但受水的电解和电极材料的限制，该类电池的输出电压大多低于1.4V，加上缺乏高比容量正负极材料，造成其能量密度低下。虽然大幅提高盐浓度能显著拓宽水系电解质电化学窗口，但使材料成本上升和电导率下降，此外还有棘手的腐蚀和盐析问题。本项目旨在避开现有的高盐浓度策略，通过溶剂化、氢键、静电吸引等多维度作用，降低水的电化学活性，开发3V宽电化学窗口水系电解质体系，并采用高容量且较低电位的硫化聚丙烯腈(S@pPAN)为负极材料，较高电位和低成本的硅酸锰钠为正极材料，构建近1.6V的新型高能水系钠离子电池。研究界面成膜反应与析氢反应的竞争与调控机制，通过电解质本体的固水与界面的阻水双重作用，抑制析氢/析氧和其它副反应，改善电池的电化学循环可逆性，切实推动高性能水系钠离子电池的发展与应用。

Aqueous Na-ion batteries with low cost and high safety are expected to be applied in the large-scale energy storage. Increasing the energy density could further reduce the use-cost and extend the application range. However, due to limitation of water electrolysis and electrode materials, the voltage output of this type of battery is still lower than 1.4 V. Additionally, it is short of high capacity cathode and anode materials. All of these lead to low energy density. Although the electrochemical window of aqueous electrolytes can be extended by use of high salt concentration, it results in high material cost and reduced ionic conductivity. In addition, intractable corrosion and salting-out emerge. This project is to avoid the high salt concentration strategy, reduce the electrochemical activation of water via multiple actions such as solvation, hydrogen bond and electrostatic attraction, and develop aqueous electrolyte systems with 3V wide electrochemical window. Moreover, sulfurized polyacrylonitrile (S@pPAN) with high capacity and relatively low potential will be used as anode material and sodium manganese silicate with relatively high potential and low cost as cathode material to assemble a new-style 1.6V aqueous Na-ion cell with high energy density. The mechanisms of competition and regulation between the interfacial filming reaction and hydrogen evolution will be investigated. In order to improve the electrochemical cycling reversibility of the cells, the hydrogen/oxygen evolution and other side-reactions would be suppressed by dual actions, that is, confining water molecules within the electrolytes and preventing water through the interphase layer. This work could strongly push the development and application of high energy aqueous Na-ion batteries.