Restraining the Octahedron Collapse in Lithium and Manganese Rich NCM Cathode toward Suppressing Structure Transformation

• Published in: Advanced energy materials 2022-09, Vol.12 (35), p.n/a
• Main Authors: Xu, Zhou, Guo, Xingzhong, Wang, JunZhang, Yuan, Yifei, Sun, Qing, Tian, Rui, Yang, Hui, Lu, Jun
• Format: Article
• Language: English
• Subjects: Cathodes; Chemical bonds; Cobalt compounds; coordination bond interactions; Density functional theory; Discharge; Electric potential; Ion migration; Lithium; Lithium-ion batteries; LMRNCM; Manganese; Oxygen; Polyacrylonitrile; polyacrylonitrile binders; surface modifications; transition metal ions; Transition metals; Voltage
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.202201323

Lithium and manganese rich nickel cobalt manganese oxide (LMRNCM), as an attractive high energy density cathode for advanced lithium‐ion batteries (LIBs), suffers from inevitable lattice oxygen release, irreversible transition metal (TM) ion migration, and interface side reactions at high charge cut‐off voltage. Herein, a facile and efficient surface strategy is proposed to stabilize the layered structure by regulating the chemical bond interaction between the polyacrylonitrile (PAN) binder and the LMRNCM particles. Due to the high retention of discharge specific capacity and average discharge voltage, the energy density retention of the PAN‐modified LMRNCM sample is up to 80.12% after 300 cycles at 100 mA g−1 current density, and the initial Coulombic efficiency and rate capacity are also improved simultaneously. Experimental and density functional theory evidence demonstrates that the exceptional performance is caused by the coordination bond interaction between the carbon‐nitrogen‐triple‐bond of PAN and the TM ion in the unstable transition metal oxygen octahedron. The interaction suppresses the irreversible migration of TM ions by increasing the energy barrier, and ensures that the PAN adheres to the LMRNCM particles tightly, which relieves electrolyte corrosion and enhances cohesiveness. This work exploits a modification strategy to stabilize the LMRNCM‐layered structure for high‐energy density LIB applications. Carbon‐nitrogen‐triple‐bonds are introduced by using polyacrylonitrile as a binder for a lithium and manganese rich nickel cobalt manganese cathode. The coordination bond interaction between the carbon‐nitrogen‐triple‐bond and the unstable transition metal ion suppresses the collapse of the transition metal oxygen octahedron. The interaction also alleviates the corrosion of the electrolyte and the stripping of cathode particles from the current collector.