Defect character distribution regulation of alloy foil anode for high volumetric energy density lithium ion battery

Alloy foil anode exhibits an intriguing potential for high volumetric energy density (HVED) lithium ion batteries (LIBs). However, limited lithiation site and disproportionate lithiation rate of foil always induce sluggish lithiation kinetics, serious volume variation and stress concentration. Here, multiple length scaled defects of a Sn-Zn eutectic alloy foil including phase boundaries (PBs), grain boundaries (GBs), and dislocations (DLs) are synergistically densified as primary diffusion conduits to promote lithiation kinetics and uniform volume variation. Lithiation generated DLs can traverse cross the dense and strengthened PBs with semi-coherent lattice matching, delocalizing stress concentration and retarding crack initiation and propagation. Refined GBs also adsorb DLs for further stress relaxation. Over intrinsic DLs density aggravates stress concentration rather than relaxing due to immobile DLs accumulation. This defect character distribution dependent behavior endows LIBs with HVED (∼1000 Wh L−1) and good cycle performances, offering unprecedented options for intrinsically safe, low cost, and HVED LIBs.