Design of a hydrolysis‐supported coating layer on the surface of Ni‐rich cathodes in secondary batteries. (8th June 2022) - Park, Jeongeun
Summary: The formation of Li4 SiO4 (LSO) coating layer on LiNi0.88 Co0.05 Mn0.07 O2 (LNCM) was achieved by incorporating a new tetraethyl orthosilicate (TEOS)‐dropping coating method. This concept includes the hydrolysis reaction of TEOS on the surface of Ni0.88 Co0.05 Mn0.07 (OH)2 and the subsequent calcination process with lithium source to obtain LSO‐coated LNCM cathode materials successfully during the calcination process. This method provides the driving force for the formation of a more uniform and thin coating layer compared with the traditional wet‐chemical coating method. The bare LNCM and LSO‐coated LNCM showed similar capacity retention rates during room temperature (25°C) cycling, but the capacity retention of LSO‐LNCM (81.6% after 100 cycles) for the cycling test at elevated temperature was significantly increased compared with bare LNCM (63.69% after 100 cycles). Additionally, the Li‐ion accessibility of the coated LNCM electrode was improved by the existence of the Li‐containing coating materials, and the results of analysis by the galvanostatic intermittent titration technique (GITT) confirmed the better Li‐ion diffusivity of the coated sample. These results indicate the high possibility of this novel coating method for application in various materials for developing secondary batteries. Abstract : A uniform and thin Li4 SiO4 coating layer was formed on the surface of high‐Ni cathode materials by introducing a driving force that facilitates the hydrolysis of TEOS to occur only on the surface of NCM(OH)2 particles. The surface deterioration and capacity fading of high‐Ni LNCM materials were effectively suppressed by the Li‐ion‐conductive LSO coating layer.