A gradient oxy-thiophosphate-coated Ni-rich layered oxide cathode for stable all-solid-state Li-ion batteries
Jianwen Liang, Yuanmin Zhu, Xiaona Li, Jing Luo, Sixu Deng, Yang Zhao, Yipeng Sun, Duojie Wu, Yongfeng Hu, Weihan Li, Tsun‐Kong Sham, Ruying Li, Meng Gu, Xueliang Sun
Abstract
Abstract High-energy Ni-rich layered oxide cathode materials such as LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) suffer from detrimental side reactions and interfacial structural instability when coupled with sulfide solid-state electrolytes in all-solid-state lithium-based batteries. To circumvent this issue, here we propose a gradient coating of the NMC811 particles with lithium oxy-thiophosphate (Li 3 P 1+x O 4 S 4x ). Via atomic layer deposition of Li 3 PO 4 and subsequent in situ formation of a gradient Li 3 P 1+x O 4 S 4x coating, a precise and conformal covering for NMC811 particles is obtained. The tailored surface structure and chemistry of NMC811 hinder the structural degradation associated with the layered-to-spinel transformation in the grain boundaries and effectively stabilize the cathode|solid electrolyte interface during cycling. Indeed, when tested in combination with an indium metal negative electrode and a Li 10 GeP 2 S 12 solid electrolyte, the gradient oxy-thiophosphate-coated NCM811-based positive electrode enables the delivery of a specific discharge capacity of 128 mAh/g after almost 250 cycles at 0.178 mA/cm 2 and 25 °C.