In-situ formed Co nano-clusters as separator modifier and catalyst to regulate the film-like growth of Li and promote the cycling stability of lithium metal batteries

Abstract

Lithium metal batteries (LMBs) are considered a highly prospective next-generation energy storage technology. However, their large-scale commercial application is hampered by the uncontrollable growth of Li dendrites, which accompany the boundless inflation of the battery's volume. In this study, we address this challenge by fabricating a porous structure of the MOF-derived CoP nanocube film (CoP-NC@PP) as a adorned layer for the separator. During the initial cycle, this film facilitates the in situ formation of Li3P with ultrahigh ionic conductivity and a lithiophilic Co, which helps rule the nucleation and deposition behavior of lithium and stabilizes the solid-electrolyte interphase. The symmetric cell incorporating the CoP-NC@PP modified layer exhibits exceptional cycling stability, surpassing 1500 h of continuous operation. The kinetic process of Li interaction with CoP and the structural factors contributing to the high cycling stability and high naminal voltage were investigated by molecular dynamics simulation and density functional theory calculations. Furthermore, full cells employing Li||CoP-NC@PP||LFP (LFP = LiFePO4) configurations demonstrate excellent cycling stability and high capacity, even at a high rate of 5 C (≈5.2 mA cm−2), with the cathode mass loading reaching as high as 10.3 mg cm−2.