Heteroatom-rich polymers as a protective film to control lithium growth for high-performance lithium-metal batteries

To overcome the safety hazard and poor cyclability resulting from the formation of lithium (Li) dendrites and “dead Li”, we report a facile strategy to control the growth of Li and stabilize the interface by covering the surface of metallic Li with three-dimensional networked carboxymethylcellulose sodium/thiourea (CMC/SN) polymers with abundant heteroatoms. The strong adsorption energy of heteroatoms with Li and the high elasticity of CMC/SN films can limit longitudinal growth and facilitate lateral growth of Li to form flat pie-type morphology and decrease the contact of Li with electrolyte, which avoid the formation of Li dendrites and excessive solid electrolyte interphase (SEI) layers. Metallic Li electrodes with CMC/SN protective layers possess high coulombic efficiency even after 210 cycles and sustain stable plating and stripping processes for 1500 h at the current density of 2 mA cm⁻². This study provides an effective method to construct polymeric layers with rich heteroatoms on Li surface for suppressing the growth of Li dendrites and improving the interfacial stability and contributes to the practical application of Li metal anodes.