The Overlooked Role of Copper Surface Texture in Electrodeposition of Lithium Revealed by Electron Backscatter Diffraction

Ultrathin Cu foils play an important role in current Li-ion batteries and next-generation anode-free Li metal batteries. The surface microstructure of the Cu foil should impact the Li deposition on Cu, but a mechanistic understanding is surprisingly lacking. In this work, we employ electron backscatter diffraction to obtain statistical information on the surface texture of two archetypical ultrathin (10 μm-thick) Cu foil samples (i.e., electrodeposited Cu foil and rolled-annealed Cu foil, denoted as ED-Cu and RA-Cu). We discovered that the ED-Cu and RA-Cu foils are distinct in surface grain morphology, preferred grain orientation, and misorientation angle distribution. The front and back surfaces of the ED-Cu foil also differed in grain size and grain boundary (GB) microstructure. We further show that the grain size and the spatial distribution of the deposited Li particles can be correlated with the density of the low Σ coincidence site lattice type of GBs at the Cu surface, which plays a previously under-appreciated role in the nucleation and the subsequent growth processes of Li electrodeposition on Cu.