Abstract
The passivation of the cathode substrate by Li2S during discharge is particularly pronounced in conditions such as high S content, crucial for practical Li-S batteries. Yet, actively regulating this phenomenon through cathode substrate exploration remains a challenging task. This study unveils that Li-intercalating oxides like Nb2O5, which undergo lithiation at discharge potentials, can induce passivation-free 3D Li2S growth, while oxides such as WO3 and MoO2, which do not undergo lithiation at discharge potentials, exhibit 2D growth. Specifically, during discharge, the electrodeposition of Li2S kinetically inhibits lithiation, prompting lithiation from Li2S instead of from the electrolyte Li salt; this process leads to the bulk diffusion of dissociated S2− and its 3D deposition. Utilizing a CNT cathode substrate incorporating lithiating oxides, we achieve high S utilization and high cell performance under conditions of high S loading with a lean electrolyte. This includes a discharge capacity of 1620 mAh g−1 at 0.03 C, equivalent to 97 % S utilization, and substantial capacities of 11.0 mAh cm−2 and 6.40 mAh cm−2 under high sulfur loadings of 14 mg cm−2 and a lean electrolyte of E/S = 5, respectively.
Published Version
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