Bulk Nanostructured Materials Design for Fracture-Resistant Lithium Metal Anodes.

Li metal is an ideal anode for next-generation batteries because of its high theoretical capacity and low potential. However, the unevenly distributed stress in Li metal anodes (LMAs) induced by volume fluctuation may cause the electrode to fracture easily, especially during high-rate plating/stripping processes. Here fracture-resistant LMAs using the concept of bulk nanostructured materials are designed via a metallurgical process. In bulk nanostructured Li (BNL), ionic conducting phases exist at grain boundaries, which promote Li+ transport. The refined Li grain size and precipitation hardening in BNL enhances the mechanical strength and fatigue endurance, alleviating the unevenly distributed stress and preventing electrode pulverization. Density functional theory is used to investigate the binding energy between Li and various kinds of oxides and SiO2 is found to be optimal additive among screened oxides. BNL has 91% of the theoretical capacity of Li metal. In full cells with BNL anode, LiFePO4 could deliver capacity of 90 mAh g-1 at 10C, an order of magnitude higher than that in full cells with Li foil anode. This strategy is expected to pave the way for fracture-resistant LMAs in high-rate cycling with maximum capacity.