Lithium‐Ion Accelerated Regulators by Locally‐Zwitterionic Covalent Organic Framework Nanosheets

Abstract

AbstractRational regulation of the Li‐ion (Li+) migration behaviors and charge distribution at the electrolyte–electrode interface is of great significance in pursuit of high‐performance lithium metal battery (LMB) chemistry. Herein, unique locally‐zwitterionic covalent organic framework nanosheets (ziCOFNs) are developed as Li+ accelerated regulators, whose functions include not only kinetics‐boosted Li+ migration but also induces uniform charge distribution in LMBs. The zwitterions act as “dissociation enhancers” to trigger efficient Li+ desolvation, while the abundant ─COO− units within the nanopores favor rapid Li+ diffusion. In addition, the ordered ionic skeleton dynamically homogenizes the interfacial charge, thereby inhibiting Li dendrite growth and stabilizing the Li‐interface chemistry. When implemented as a functional interlayer in the cell configuration, ziCOFNs display ultrahigh transfer number (0.84) and ionic conductivity beyond 4.5 mS cm−1. With such a layer, stable Li plating/stripping (over 6500 h) at 3 mA cm−2 in symmetric cells, and superior long‐term cycle performance in high‐loading LiFePO4 (9.4 mg cm−2) full cells are achieved. Detailed experimental characterizations combined with theoretical calculations elucidate the mechanism of the zwitterionic framework tuning Li+ migration behaviors. This work is anticipated to shed fresh light on the exploration of zwitterionic crystalline materials in next‐generation LMBs.