清华大学张强团队提出了实用复合锂阳极的连续转换去插层(CTD)剥离机理。这一研究成果于2021年12月10日发表在国际顶尖学术期刊《美国化学会杂志》上。

锂（Li）金属阳极对高能量密度电池具有吸引力。根据转化反应，沉积的锂在脱锂过程中不可避免地会产生死锂，从而严重消耗活性锂和电解质，导致寿命短。

该文中，研究人员通过操纵阳极的过电位来抑制死锂的产生，提出了一种连续转换-脱交错（CTD）脱锂机制。初始循环中的剥离仅通过锂金属的转化反应进行。循环后，当阳极的过电位高于锂化石墨的脱锂电位时，就会触发脱锂反应，从而完成整个CTD脱锂过程，从而大大减少因高度可逆的脱锂反应而形成的死锂。在实际条件下，基于CTD剥离机制的工作电池可维持210次循环，容量保持率为80%，而裸锂阳极为110次循环。此外，具有CTD剥离机制的1 Ah袋式电池可运行150个周期。

该工作巧妙地通过操纵阳极的脱锂机制来抑制死锂的产生，并为实际复合锂阳极的设计提供了新的概念。

附：英文原文

Title: A Successive Conversion–Deintercalation Delithiation Mechanism for Practical Composite Lithium Anodes

Author: Peng Shi, Li-Peng Hou, Cheng-Bin Jin, Ye Xiao, Yu-Xing Yao, Jin Xie, Bo-Quan Li, Xue-Qiang Zhang, Qiang Zhang

Issue&Volume: December 10, 2021

Abstract: Lithium (Li) metal anodes are attractive for high-energy-density batteries. Dead Li is inevitably generated during the delithiation of deposited Li based on a conversion reaction, which severely depletes active Li and electrolyte and induces a short lifespan. In this contribution, a successive conversion–deintercalation (CTD) delithiation mechanism is proposed by manipulating the overpotential of the anode to restrain the generation of dead Li. The delithiation at initial cycles is solely carried out by a conversion reaction of Li metal. When the overpotential of the anode increases over the delithiation potential of lithiated graphite after cycling, a deintercalation reaction is consequently triggered to complete a whole CTD delithiation process, largely reducing the formation of dead Li due to a highly reversible deintercalation reaction. Under practical conditions, the working batteries based on a CTD delithiation mechanism maintain 210 cycles with a capacity retention of 80% in comparison to 110 cycles of a bare Li anode. Moreover, a 1 Ah pouch cell with a CTD delithiation mechanism operates for 150 cycles. The work ingeniously restrains the generation of dead Li by manipulating the delithiation mechanisms of the anode and contributes to a fresh concept for the design of practical composite Li anodes.

DOI: 10.1021/jacs.1c08606

Source: https://pubs.acs.org/doi/10.1021/jacs.1c08606