Polydopamine‐induced nano‐coating layer for high stability of nickel‐rich cathode in secondary batteries
Seunghak Lee, Jeong‐Eun Park, Eunjeong Seok, Minjun Kim, Minkyeong Ku, Hyojun Lim, Sang‐Ok Kim, Heechul Jung, Wonchang Choi
Abstract
High-Ni layered-oxide cathodes are the most prospective cathode materials for next-generation Li-ion batteries (LIBs) in electric vehicles (EVs) owing to their high specific capacity. However, High-Ni layered-oxide cathode materials exhibit inferior cyclability and low thermal stability owing to the side reaction between Ni4+ and the electrolytes. To solve these surface-related problems, we proposed a strategy for forming LiNbO3 (LNO)—with outstanding thermal stability and ionic conductivity—on a Ni-rich layered-oxide surface using polydopamine (PDA). The PDA formed on the transition metal hydroxide surface has copious catechol OH groups, which attract the Nb ions in the solution to form a LNO coating layer during the calcination process. The LiNi0.8Co0.1Mn0.1O2 (pristine LNCM) electrode experiences enormous degradation when cycled after being subjected to severe conditions—such as a full charge and a 60°C storage test—but the LiNbO3-coated LNCM (LNO-LNCM) electrode exhibits particularly stable cycling performance. Furthermore, differential scanning calorimetry (DSC) results exhibited that the LNO coating notably ameliorated the thermal stability of the cathode material. As a result, our experimental results suggest that the development of cathode materials that can withstand greatly oxidized states and high-temperature environments is achievable.