新型水系混合阳离子二次电池的基本原理及应用研究

As current aqueous rechargeable batteries cannot meet the demands from large-scale energy storage, it is necessary to develop new fundamental concepts to build aqueous batteries. Following our basic concept of “Li+/Na+ mixed-ion electrolytes”, a complete concept of “mixed-cation electrolytes” is proposed to be employed to construct aqueous rechargeable batteries (mixed-cation battery) in the project. Such batteries operate based on two cations as charge transfer ions, which are unlike the conventional “rocking chair” aqueous metal-ion batteries on a basis of the immigration of one metal-ion between cathode and anode. During charging and discharging, the concentration and/or composition of the different cations in the electrolytes are changed. Our project is aimed at exploring a couple of new battery systems based on aqueous mixed-cation electrolytes through rationally screening, combining and modifying the cation-intercalated compounds, and illustrating the intrinsic properties of the relevant electrode materials (ionic selectivity and anion-cointercalation property) as well as the “double-cations working” mechanisms of the new battery systems. The new batteries with energy density above 50 Wh Kg-1, power density above 1000 W Kg-1, cycle life times over 500 and working voltage close to 2 V are expected to be achieved. The studies will provide important fundamental and practical contributions to the development and application of new aqueous batteries.

现有水系二次电池都难以满足未来大规模储能的需要，所以发展新概念或新理论来构建新电池体系是非常有必要的。基于此，本项目拟进一步扩展我们原有的“锂钠混合离子”概念至“混合阳离子”来构建新型水系二次电池，即混合阳离子二次电池。该电池工作是依赖于两种阳离子的迁移，不同于传统的摇椅式金属离子电池只是依赖一种金属离子工作的；其在充放电过程中，电解质中两种阳离子的浓度和组成是变化的。本项目将通过合理的筛选、组合和改性各类阳离子嵌入型电极材料，探索出若干个以混合阳离子水溶液为电解质的新电池体系；理论和实验相结合揭示相关电极材料的离子选择性及离子共嵌性等本质特征和阐明新电池的“双阳离子工作”机制。期望获得比能量大于50 Wh Kg-1，比功率密度大于1000 W Kg-1，循环寿命大于500次和工作电压接近2 V的新电池体系。本项目的研究将为新电池的发展和应用提供必要的实验依据及理论基础。

本研究构建了原创的高电压及高比能电池体系四类，阐明金属铁氰化物和石墨烯的离子嵌入机制及本质特征。.1. 铁氰化铟基高电压水系混合离子电池：采用铁氰化铟为正极、磷酸钛钠和焦磷酸钛为负极、混合离子水溶液为电解质构建出三种电池。其中，电池工作电压最高达1.6 V，能量密度为56 Wh/kg，功率密度超2700 W/kg。揭示铁氰化铟中水调控碱金属离子嵌入机制：对于锂/钠离子，水分子可提高其嵌/脱电位并降低其嵌脱反应的动力学，对于钾离子，水分子则不参加嵌脱反应。.2. 铁氰化锌基高电压水系锌离子电池：利用“晶体调控生长”的策略制备了立方、截角和正八面体三种形貌的铁氰化锌微米颗粒，揭示了其电化学性能与颗粒形貌的关系，与金属锌负极构建出工作电压为1.7V和能量密度达100 Wh/kg的电池。.3. 铁氰化铜基高电压水系混合离子电池：采用铁氰化铜为正极、磷酸钛钠和焦磷酸钛为负极、混合离子水溶液为电解质构建出三种电池。其中，电池工作电压最高达1.6V，能量密度为56Wh/kg，功率密度达3000 W/kg。揭示铁氰化铜中离子选择性：钾离子>钠离子>锂离子。.4. 铝-石墨烯超级电池：采用多层石墨烯为正极、金属铝为负极、离子液体为电解液，构建出具有超长循环寿命和超高倍率性能的2V电池，揭示石墨烯材料的厚度和横向尺寸对铝氯酸根离子的嵌/脱行为的影响规律。