Work-Function-Induced Interfacial Electron/Ion Transport in Carbon Hosts toward Dendrite-Free Lithium Metal Anodes

Coupled electron/ion transport is a decisive feature of Li plating/stripping, wherein the compatibility of electron/ion transport rates determines the morphology of deposited Li. Local Li+ hotspots form due to inhomogeneous interfacial charge transfer and lead to uncontrolled Li deposition, which decreases the Li utilization rate and safety of Li metal anodes. Herein, we report a method to obtain dendrite-free Li metal anodes by driving electron pumping and accumulating and boosting Li ion diffusion by tuning the work function of a carbon host using cobalt-containing catalysts. The results reveal that increasing the work function provides an electron deviation from C to Co, and electron-rich Co shows favorable binding to Li+. The Co catalysts boost Li+ diffusion on the carbon fiber scaffolds without local aggregation by reducing the Li+ migration barrier. The as-obtained dendrite-free Li metal anode exhibits a Coulombic efficiency of 99.0 %, a cycle life of over 2000 h, a Li utilization rate of 50 %, and a capacity retention of 83.4 % after 130 cycles in pouch cells at a negative/positive capacity ratio of 2.5. These findings provide a novel strategy to stabilize Li metal by regulating the work function of materials using electrocatalysts. A carbon fiber host with high work function was designed to promote electron transfer and surface Li+ diffusion, thus leading to uniform dendrite-free Li deposition on the fiber scaffold. The as-obtained dendrite-free Li metal anode exhibited high reversibility and long-term cycling stability (EVac: vacuum level; Ef : Fermi level; EVBM: maximum valence-band energy level; ECBM: minimum conduction-band energy level).image

Automated summary

By tuning the work function of a carbon host using cobalt-containing catalysts, a method to obtain dendrite-free Li metal anodes is reported, achieving high Coulombic efficiency, long cycle life, high Li utilization rate and stable Li deposition.