Plasma assisted synthesis of LiNi0.6Co0.2Mn0.2O2 cathode materials with good cyclic stability at subzero temperatures

Abstract Layered Ni-rich cathode materials, LiNi0.6Co0.2Mn0.2O2 (NCM622), are synthesized via solid reaction assisted with a plasma milling pretreatment, which is resulted in lowering sintering temperatures for solid precursors. The plasma milling pretreated NCM622 cathode material sintered at 780 ℃ (named as PM-780) demonstrates good cycling stability at both room and subzero temperatures. Specifically, the PM-780 cathode delivers an initial discharge capacity of 171.2 mAh g−1 and a high capacity retention of 99.7% after 300 cycles with current rate of 90 mA g−1 at 30 ℃, while stable capacities of 120.3 and 94.0 mAh g−1 can be remained at −10 ℃ and −20 ℃ in propylene carbonate contained electrolyte, respectively. In-situ XRD together with XPS and SEM reveal that the NCM622 cycled at −10 ℃ presented better structural stability and more intact interface than that of cathodes cycled at 30 ℃. It is also found that subzero temperatures only limit the discharge potential of NCM622 without destroying its structure during cycling since it still exhibits high discharge capacity at 30 ℃ after cycled at subzero temperatures. This work may expand the knowledge about the low-temperature characteristics of layered cathode materials for Li-ion batteries and lay the foundation for its further applications.