Preserving the Li {110} texture to achieve long cycle life in Li metal electrode at high rates

Abstract

{110} textured Li metal electrode shows superior cycle performance when compared to its counterparts with other crystallographic textures or no texture. However, at high rates it suffers from a shortened cycle life that becomes significant with large cycling capacities – a common problem for most alkaline metal electrodes. In the present work, the morphological and structural evolution of the texture-dependent Li electrodes cycled at different current densities is investigated and discovered that the cycling current density affected both the morphological and the crystallographic texture evolution of Li {110} metal electrode. In particular, loss of {110} texture at increased current densities accelerated the morphological deterioration of Li, leading to roughened Li plating and loose Li packing, and thus promoting the undesired consumption of Li and electrolyte. Thereafter a low-rate-healing strategy that significantly elongated the cycle life of Li metal electrode cycled at high rates is proposed. By adopting the healing strategy, a Li||Li symmetrical cell cycled at 10 mA cm−2 with a capacity of 10 mAh cm−2(with a 50% depth of discharge) can last for >800 runs, and a Li||LFP full cell can run for >300 cycles at 5 C with virtually no capacity degradation compared to the first cycle after activation.