Unraveling the high temperature cycling performance of high-nickel LiNi0.85Co0.10Mn0.05O2 cathode materials in pouch-type full cells

Abstract High-nickel layered LiNi0.85Co0.10Mn0.05O2 cathode materials possess great potential for the development of high energy density lithium-ion batteries with long cycle life. Herein, the structural and electrochemical performance of the as-prepared LiNi0.85Co0.10Mn0.05O2 cathode both at 25 °C and 45 °C is systematically evaluated in a pouch-type full cells with graphite as the anode. The LiNi0.85Co0.10Mn0.05O2/C full cells at 25 °C provided impressive cycling performance (81% capacity retention after 1073 cycles), however, cycling at 45 °C resulted in 76% capacity retention after 300 cycles. Our failure analysis shows that charge/discharge cycling at 45 °C triggered severe microcracks generation, electrolyte decomposition and subsequent impedance growth in the LiNi0.85Co0.10Mn0.05O2 cathode, while the graphite anode remained stable throughout. It is believed that appropriate doping and surface modification techniques should be developed to stabilize the bulk and surface structure of the high-nickel cathode materials to attain stable high temperature long-term cycling performance.