碳纳米复合电极的构建及其在可弯折水系锌离子电池中的研究

The rapid development of electronic devices with wearable characteristics requires energy storage system to endure large foldable strain. In this program, a strategy to controllably assemble nanocarbon materials and their derivatives will develop to construct macroscopic electrodes. The good coupling between nanocarbon materials and cathodes materials at “molecular level” would be realized via adjusting their interactional effect. These composites exhibit an enhanced performance due to a synergistic effect by combining the virtues of the two types of materials. The interaction and compatibility between nanocarbon materials and zinc anodes will be also studied to develop efficient strategies for enhancing the interfaces. As a result, the 3D zinc anode with high mechanical strength and structure stability can be obtained. The Zn2+ transfer rate and dendrite-free anode during the charge/discharge process, effecting with the porous structures of electrodes would be investigated in detail. In order to optimize the configurations of electrodes, the in-situ testing platform will be fabricated to characterize the morphology of these nanocarban-based electrodes during the different folding strain states. We attempt to analyze the morphology transformation under various folding strains, achieving the foldable zinc-ion batteries. The completion of this program would enlighten the theoretical and experimental design and preparation of novel energy storage systems.

随着新型可穿戴电子设备的迅猛发展，需要开发出与之相匹配的能够承受较大弯折应变的储能系统。本项目拟以发展可控制备碳纳米材料及其异质结构宏观体的策略，研究通过调节碳纳米材料与正极材料之间的相互作用力，实现它们彼此间“分子级别”的复合，有效地将功能纳米材料和碳纳米材料自身优异性能从微观到宏观进行转移；同时研究增强锌负极与碳纳米基底界面结合力的策略，构筑机械强度高、结构稳定的三维多孔锌负极，探索其孔道结构对充放电过程中锌离子传输速率以及抑制枝晶生长的影响规律。搭建在不同弯折状态下原位观测电极形貌结构的平台，综合分析弯折应力作用于电极微观形貌的演变过程，进而优化电极结构的稳定性，从而实现可弯折水系锌离子电池的组装。研究结果将为实现新型储能系统提供理论指导与实验依据。

本项目以实现可折叠水系锌离子电池为目的，开展了高性能钒基正极材料的制备、锌负极双层保护的策略以及可折叠锌离子电池器件的组装。首先，基于客体预嵌入策略，避免水热法，利用室温下自聚合法用于合成PEDOT嵌入V2O5•nH2O。PEDOT可以扩大钒氧化物 (001)面晶格间距，并且PEDOT包覆V2O5•nH2O，抑制正极材料在水系电解液中溶解。更重要的是，PEDOT在V2O5•nH2O表面产生氧空位(Vö)，Vö调节V2O5•nH2O的电子结构和表面化学，触发快速的电子转移，从而提高电极的电化学性能，电池在3000次循环后仍可达到253 mAh g-1的高比容量，容量保持率为90.7%。然后，利用导电涂层有利于降低局部电流密度，绝缘多孔涂层促使锌离子在相界面均匀分布，两种涂层均有利于锌负极的均匀沉积。采取导电-不导电双层协同效应，实现了超过1300小时的稳定电镀/剥离。在2 mA cm-2下进行1000次循环后，库伦效率保持在99.2%。最后，采用喷涂法制备独立的CaV4O9/碳纳米管(CaVO/CNTs)复合膜，舍弃集流体质量，作为水系锌离子电池正极，CaV4O9微米花分散在CNTs网络中，提供了快速的电子转移动力学。组装水系锌离子电池，首圈充电转化反应提取碱土金属离子，相转化为无定形相，提供跟多暴露的离子通道，促进Zn2+快速嵌入/脱出。基于软包柔性Zn//CaVO/CNT电池，并在不同形变状态下展示了稳定的可折叠电化学性能。