A lithiophilic TiN-carbon scaffold for lithium-metal anodes, with SEI ionic conductivity boosted by Li3N formation

Abstract

Self-supporting TiN-modified carbon fibre electrodes (TiN@C) were prepared by a simple nitriding process and tested as lithiophilic, 3D, conductive skeletons. The TiN@C hosts have homogenously distributed lithiophilic nucleation sites and develop a Li₃N-rich secondary electrolyte interphase layer with high ionic conductivity. Their improved kinetic performance relative to carbon frameworks, including charge and mass transfer processes, are explored through various electrochemical tests, ex situ characterisation of the electrodes and theoretical calculations. The assembled TiN@C electrodes achieve a dendrite-free morphology even at a relatively high capacity of 20 mA h cm^-2. The high electronic conductivity of TiN@C and ionic conductivity of the Li₃N formed in situ improve charge and mass transfer. The electrodes achieve a Coulombic efficiency over 99.3% and outstanding lifetime over 200 cycles with a low electroplating overpotential of -15 mV vs Li/Li + . Lithiated Li@TiN@C based symmetric cells and full cells assembled with LiFePO₄ both exhibit better cycling stability and rate performance compared with Li@C cells made similarly.