Self-standing TiC-modified carbon fibre electrodes derived from cellulose and their use as an ultrahigh efficiency lithium metal anode

Lithium metal anodes could be a key component of high energy density rechargeable batteries, but uncontrolled growth of Li dendrites, large volume expansion, and unstable solid electrolyte interface films seriously hinder the practical applications of Li metal batteries. In this work, a self-standing three-dimensional TiC-modified carbon fibre (TiC@C) network has been fabricated by carbothermal reduction. Binding energy calculations reveal that Li is preferentially plated on TiC rather than the bare C skeleton. The lithiophilic TiC not only serves as a Li nucleation site to assist homogeneous Li deposition, but it also enables rapid Li deposition due to its high electronic conductivity. The 3D conductive structures with high surface area play an important role in reducing the local current density, and also accommodate Li volume changes during repeated cycling. As a result, the TiC@C electrode achieves a nearly zero Li nucleation overpotential and low voltage hysteresis of 150 mV at 2 mA cm(-2). Passing 1 mA h cm(-2) charge, the coulombic efficiency (CE) was found to be 99.6% over more than 200 cycles. Furthermore, full cells assembled with a LiFePO4 cathode in a conventional carbonate electrolyte achieve an impressive capacity retention of 87% over 250 cycles. This work demonstrates a novel design of a 3D lithiophilic host for dendrite-free lithium metal anodes.

Automated summary

A self-standing three-dimensional TiC-modified carbon fibre network is fabricated via carbothermal reduction, which provides a solution for the problems of Li dendrite formation, large volume expansion, and unstable solid electrolyte interface films in lithium metal batteries. The lithiophilic TiC promotes homogeneous and rapid Li deposition, while the 3D conductive structures with high surface area reduce local current density and accommodate volume changes. The TiC@C electrode shows a nearly zero Li nucleation overpotential and low voltage hysteresis, achieving a coulombic efficiency of 99.6% over 200 cycles and an impressive capacity retention of 87% over 250 cycles in full cells with LiFePO4 cathode.