水溶液Zn基可充电化学储能电极材料及体系研究

Zn metal has been regarded as anode for aqueous batteries for a long time, because of its merits, such as low cost, environmental benignity, high capacity and so on. Due to the limited electrochemical window in aqueous electrolyte, and the low performance of electrode materials, the energy density, power density and cycle life of Zn based aqueous rechargeable energy storage systems still need to be further improved. To address these problems aforementioned, three parts of the research are proposed: (1) Mechanism study of Zn metal stripping and plating processes; (2) Selection and study on redox reaction mechanisms of Zn2+ storage- and non-Zn2+ storage- electrode materials for Zn-based rechargeable aqueous energy storage systems; (3) Combination of different electrode materials and construction of new energy storage systems, in which the components and pH value of the electrolyte are adjusted for a higher working voltage. We are aiming to obtain effective methods of preparation and modification for Zn electrode, as well as Zn2+ storage- and non-Zn2+ storage- electrode materials. With these methods, the utilization and structural stability of Zn metal anode can be enhanced, cycle and rate performance of Zn2+ storage- and non-Zn2+ storage- electrode materials can be improved, and Zn based rechargeable aqueous energy storage systems with high electrochemical performance can be built.

Zn元素价格便宜、环境友好、比容量高，基于Zn元素的电池体系研究历史悠久，但是前期进展有限。近来水溶液可充Zn基电化学储能体系成为了研究热点之一。由于受水溶液自身电化学窗口的限制和电极材料的影响，水溶液可充Zn基储能体系的能量密度、功率密度和循环寿命都有待提高。针对这一问题，本项目拟开展以下三方面工作：（1）Zn负极结构稳定性和利用率的提高；（2）新型水溶液可充Zn基储能电极材料的筛选及其电化学反应机理的探索；（3）储能体系的构筑优化。具体研究内容如下：研究Zn电极电化学性能和溶解析出过程的影响因素及机制，得到提高Zn电极结构稳定性和利用率的方法；筛选新型Zn2+存储和非Zn2+存储的电极材料，阐明其电化学反应机理，发展优化电极材料的制备和改性方法；组合不同电极材料，构筑优化的储能体系，改性电解液，提高储能体系工作电压；得到具有高性能的水溶液可充Zn基电化学储能体系。

近来水溶液可充Zn基电化学储能体系引起广泛关注，但由于水的电压窗口低和电极材料限制，它的能量密度、功率密度和循环寿命仍需提高。针对这一问题，本项目开展水溶液可充Zn基电化学储能体系材料改性和体系开发研究，取得了以下研究成果：（1）对电沉积锌/碳复合物负极，研究发现电沉积锌的电流密度和在使用过程中的放电深度是影响电沉积锌/碳复合物电化学性能的重要因素；（2）二维层状过渡金属硫（硒）化物正极材料，尤其是VSe2，具有较大的层间距，有利于锌离子的嵌脱反应，展现出优异的倍率性能；（3）以锌金属为负极，高比表面积生物质碳材料为正极，构筑了低成本高比能的水溶液锌离子混合超级电容器；通过引入聚合物阳离子交换膜，组建了复合电解液储能器件，在正、负极采用酸（中）性、碱性电解液（两种电解液之间用Nafion膜分隔），提升了水溶液电化学储能体系的工作电压和能量密度。这些结果可以推动水溶液可充Zn基电化学储能体系的进一步发展。本项目共发表SCI论文19篇，申请专利3项，培养硕士生8名，在项目的支持下，项目负责人获得国家优秀青年基金的立项支持。