A review of naturally derived nanostructured materials for safe lithium metal batteries

Lithium metal batteries (LMBs) are regarded as one of the most promising candidates for next-generation energy storage. However, the inherent challenges of Li metal anode, such as uncontrollable dendrite growth, unstable Li/electrolyte interfaces, and infinite volume changes, induce severe safety hazards and inferior cyclic stability, dragging the LMBs still inviable currently. Natural materials have recently been signified an emerging platform to realize efficient electrodes, artificial protective layers, solid electrolytes, and separators in practical LMBs because of their versatile advantages such as low cost, renewability, excellent mechanical properties, intrinsic heteroatom-containing features, tunable porous structures, etc. In this review, systematical protective strategies for safe LMBs based on natural materials are summarized. The basic overviews of Li anode chemistry, such as solid electrolyte interfaces (SEIs) and Li dendrite, are first discussed. On basis of this theoretical understanding, naturally derived nanostructured materials for restraining dendrite growth and stabilizing Li anode are then included. Finally, a general conclusion and perspective on the future improvements of bio-based protective nanomaterials in LMBs are presented. This review builds a close connection between the sustainable natural materials and the protective strategies of Li metal anode, attempting to shed fresh light on the biomass-based materials in highly safe rechargeable LMBs.