二维过渡金属(铁/钴/镍)氮化物微纳设计、缺陷调控与锂空储能机制

Lithium air batteries have attracted great interests in large scale grid energy storage and electric vehicles applications owing to their much high theoretical energy densities, e.g. the energy density of lithium air battery as high as 10 times of lithium ion batteries, which is comparable to gasoline. However, low energy conversion efficiency, poor rate-capability and short lifespan are widely considered to be the main obstacles for their practical applications. .In this project, we mainly focus on the controllable design and synthesis of two dimensional transition metal nitrides (iron/cobalt/nickel nitrides) and solve the challenges of low catalyst activity and poor oxygen reaction kinetics of metal air batteries. We also try to clarify their intrinsic energy storage mechanism and synergistic improvement strategy and finally achieve goals for lithium air batteries: high efficiency, good stability and low cost. Generally, this project can be mainly divided into three sections: 1) developing effective protocols to synthesize two dimensional micro/nanostructure metal (Iron/cobalt/nickel) nitrides and make defects through structural evolution and topochemical approaches; 2) investigating the relationship of their micro/nanostructure, defect characteristics and performance of two dimensional metal (Iron/cobalt/nickel) nitrides by in situ operando X-ray diffraction and online electrochemical mass spectrum technique; 3) Designing and optimizing lithium air full battery devices and reveal their intrinsic storage mechanism and performance improvement strategy.

锂空气电池，具有与汽油相当的高理论能量密度，是传统锂离子电池的十倍，在大型电网储能和电动汽车领域有更大的应用前景。然而，其器件实际应用仍面临着转换效率低、倍率性能差和循环寿命短的巨大挑战。本项目选取金属(铁/钴/镍)氮化物为研究对象，设计制备二维微纳结构催化剂材料，解决金属氮化物催化剂活性低和氧反应动力差难题，阐明二维金属(铁/钴/镍)氮化物本征储能机制与协同增效策略，达到锂空气电池可实用化目标：高效、稳定、低成本。主要研究包括三个方面：1）二维金属(铁/钴/镍)氮化物材料微纳设计与缺陷调控，开发同相原位与异相拓扑精准合成方法；2）电化学原位实时探测，阐述二维金属(铁/钴/镍)氮化物微纳结构、缺陷特性与性能构效关系；3）锂空全电池器件设计与工艺优化，揭示全电池器件本征储能机制与性能提升策略。

本项目围绕锂金属空气电池器件实际应用面临着转换效率低、倍率性能差和循环寿命短等科学问题，选取过渡金属氮化物为研究对象，1）率先提出了高安全原位氨化、微波焦耳热等新方法，可控制备了系列金属氮化物、杂化材料与复合物及其多功能储能器件，揭示了材料结构、元素掺杂、缺陷态等物性演化规律、转化与调控机制，研究了其电化学催化机制和储能性能；2）搭建了原位电化学-表征技术平台（电化学-XRD、变温电化学-Raman），揭示了金属化合物电极材料与电化学储能之间的本征催化储能机制与演化规律，建立了金属化合物材料特性-器件结构-储能性能之间内在关系以及性能提升策略；3）提出电子集流体（如铝箔、铜箔）微波焦耳热界面调控策略，可控制备出了轻薄、多孔、高柔、高韧与功能化电子集流体，有效提升电子集流体表面能、亲锂特性及其储能性能，自主设计开发了功能微纳材料微波隧道联动装置与可控合成系统。