Regulation of Li⁺ Diffusion via an Engineered Separator to Realize a Homogeneous Lithium Microstructure in Advanced Li-Metal Batteries

Abstract

Lithium metal, the most promising anode material, is receiving increasing interest owing to its high theoretical capacity (3860 mA h g–1) and low negative potential (−3.04 V vs. standard hydrogen electrode). However, the uneven Li dissolution/deposition behavior causes a degraded cycle stability and safety issues, thus seriously restricting the application of Li-metal batteries (LMBs). Separator modification is one of the most versatile and feasible approaches to overcome this problem. In this study, polypropylene (PP) separators are prepared and coated with an inert hexagonal boron nitride (h-BN) layer, which can provide sufficient ion transport channels and physical protection. The h-BN@PP separator exhibits a remarkable effect on the regulation of the diffusion and nucleation of Li+ to realize a homogeneous Li microstructure, thereby reducing the voltage polarization and improving the cycle performance of the battery. All LMBs equipped with the modified separators exhibit excellent cycling stabilities. The Li|Li symmetric cell exhibits a stable cycling for over 2300 h with a polarization voltage of 13 mV. In conclusion, the modified h-BN@PP separator has significant potential for stabilizing various Li metal anodes, which strongly promotes the applications of advanced LMBs.

A Li+-flux-homogenizing separator for long-term cycling of Li metal anodes

“…Compared with other published composite separators, 17,[28][29][30][31][32][33][34][35][36] the PVDF-HFP/SN separator-based cell maintains a durable operation lifespan and high capacity retention, as shown in Fig. 1b and Table S1 (ESI †).…”

A Stabilized Li-Metal Anode with a Ti-Based Metal–Organic Framework Electronic Shield

“…Tremendous efforts have been made to restrain the adverse reactions on the Li-metal anode, such as fabrication of favorable host structures, − regulation of electrolyte compositions, − modification of separator, and so on. − Among them, electrolyte engineering to promote the in-situ formation of a stabilized SEI is one of the plausible solutions. Alternatively, the construction of an artificial SEI could be another simple approach. , As a class of porous coordination polymers, metal–organic frameworks (MOFs) have attracted increasing attention in the electrochemical community due to their large surface area, highly ordered structure, and well-developed porosity. − For example, Avery et al have demonstrated that MOFs can be used as a cathode additive to mitigate polysulfide shuttle effect in lithium–sulfur (Li–S) batteries for a better cycling performance .…”