Uniform Li Deposition through the Graphene-Based Ion-Flux Regulator for High-Rate Li Metal Batteries

Abstract

Lithium (Li) metal is considered an ultimate anode owing to its high specific capacity and energy density. However, uncontrolled Li dendrite growth and low Coulombic efficiency have limited the application of Li metal. Among various strategies introduced to address these limitations, the surface modification of polyolefin separators with functional materials has been widely adopted for improving the mechanical and thermal stabilities of polymer separators and to protect the separator from the penetration of Li dendrites. Herein, we report a new functional polymer separator that is surface-altered with a graphene-based Li-ion flux regulator (GLR) to homogenize the Li-ion flux and suppress the growth of sharp dendritic Li in Li metal batteries. The nanopores distributed through the GLR structure serve as channels for ion transport and junctions for electron transfer, facilitating efficient electrolyte penetration and rapid charge transfer between graphene (Gr) sheets. Owing to these favorable features of porous GLR, a Li−Cu cell with the GLR surfacealtered polypropylene separator (GLR-PP) delivers excellent cycle and rate performances compared to a Li−Cu cell with a Gr surface-altered polypropylene separator. In addition, among the tested cells, Li−sulfur cells with GLR-PP exhibit the most stable cycle performance over 500 cycles. These results demonstrate that the concept of tailoring the surface of a polymer separator with porous 2D materials is an effective strategy for improving the long-term cycle stability and electrochemical kinetics of Li metal-based batteries and would trigger further relevant studies.

Strategies for Enhancing the Stability of Lithium Metal Anodes in Solid-State Electrolytes

“…As Li metal is the lightest member of the alkali metal group and has the lowest reduction voltage (−3.04 V vs. standard hydrogen electrode), extensive research has been reported on highly promising next-generation anode materials [10][11][12]. However, the use of Li metal in liquid electrolytes faces many challenges owing to its high reactivity to nonuniform Li dendrite formation, which results in hazardous safety concerns (e.g., fire and explosion).…”

Facile Polymer of Intrinsic Microporosity-Modified Separator with Quite-Low Loading for Enhanced-Performance Lithium Metal Batteries

“…Lithium metal batteries (LMBs) using Li metals as anodes have attracted increasing attention in these years, as lithium metal has a quite high theoretical specific capacity of 3860 mAh/g and a pretty low redox potential. − However, the uncontrolled dendrite growth during charge/discharge cycles caused by uneven deposition on the Li anode, along with the side reactions between liquid electrolyte and Li anode, seriously hinder the wide practical application of lithium anodes. This is because uncontrolled dendrite growth may pierce the separator and cause internal short circuits, leading to a catastrophic safety risk; the parasitic reactions will continuously deplete the electrolyte, reduce the Coulombic efficiency, and shorten the lifetime. ,,,− Therefore, solving the above problems is the key to promoting the practical applications of LMBs.…”