A Coal-Derived Carbon Fiber Scaffold with Superior Mechanical Robustness for Ultra-Stable Lithium Metal Anodes

Abstract

Lithium metal anode is considered the holy grail of anode materials for next-generation high-energy-density lithium batteries. however, issues such as volume expansion and dendrite formation accelerate capacity fade and raise serious safety concerns, which severely hinders commercialization. Herein, coal-based carbon fibres exhibiting exceptional mechanical strength and rich oxygen-containing functional groups have been successfully synthesised, enabling the smooth deposition of lithium. the symmetrical cells fabricated with coal-based carbon fibers demonstrate remarkable cycling stability, exceeding 1800 h at 1 mA cm-2, their stability at a lower current density of 0.5 mA cm-2 surpasses 2800 h. This property also allowed corresponding half-cells to retain a 98.1% Coulombic efficiency across 350 cycles. Furthermore, when paired with a LiFePO4 cathode in a full cell, this anode delivers a reversible capacity of 159.5 mAh g-1 and sustains an average coulombic efficiency of 99.8% over 300 cycles. This study thereby proposes a highly promising strategy for crafting lithium metal composite anodes that achieve extended cycle life while effectively suppressing volume expansion.