Effect of strontium phosphate coating on NCM811 powders for high-performance Li-ion battery cathode

Abstract

The NCM811 cathode material, characterized by a high nickel content, is known for its substantial energy capacity but is afflicted by challenges, including electrolyte degradation and inadequate cyclic stability. In this study, a chemical bath deposition technique is utilized to apply a layer of Sr3(PO4)2 material onto the surface of NCM811 particles to address these problems. This procedure yields a continuous protective coating that shields the NCM811 particles from detrimental interactions with the electrolyte, such as HF attack and the formation of surface cracks, while also promoting the diffusion of lithium ions during charge/discharge cycles. XRD analysis indicated that the application of Sr3(PO4)2 coating did not cause any changes in the structure of the NCM811 cathode material. SEM images of all coated samples demonstrated that all coated samples have spherical morphology. Additionally, both Raman and FTIR examinations provide evidences supporting the existence of strontium phosphate material on the surface of the NCM811 cathode material. The distinctive 5.9 nm-thick Sr3(PO4)2 coating enables the NCM811 material to maintain 96 % of its capacity after 100 charge/discharge cycles in a voltage range of 2.8–4.4 V vs. Li/Li+ at a current rate of 1C.