Uniform Deposition and Effective Confinement of Lithium in Three-Dimensional Interconnected Microchannels for Stable Lithium Metal Anodes.

Lithium dendrite formation has hindered the practical implementation of lithium metal batteries with higher energy densities compared with those of conventional lithium-ion batteries. Herein, a nanoconfinement strategy to access dendrite-free lithium metal anodes comprising three-dimensional (3D) hollow porous multi-nanochannel carbon fiber embedded with TiO2 nanocrystals (HTCNF) is reported. The transport of the lithium ions is facilitated by the 3D architecture. Functioning as nanoseeds, the TiO2 nanocrystals guide the lithium ions toward forming uniform deposits, which are further confined inside the hollow carbon fibers and the 3D HTCNF layer. Site-selective deposition coupled with the nanoconfinement of lithium metal modifies the Li plating/stripping behavior and effectively suppresses the dendrite growth. The HTCNF-Li cell delivers a stable cycling performance of 1300 h with a voltage hysteresis as low as 6 mV. The assembled HTCNF-Li//LiFePO4 full cell displays a compelling rate performance and enhanced cycling stability with high capacity retention (90% after 400 cycles at 0.5 C). Our results demonstrate a new and potentially scalable route to resolve the lithium dendrite growth issue for enhanced electrochemical performances, which can be further extended to other metal battery systems.