Plasma assisted synthesis of LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2) cathode materials with good cyclic stability at subzero temperatures

摘要

Layered Ni-rich cathode materials,LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(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°C(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°C,while stable capacities of 120.3 and 94.0 m Ah g^(-1) can be remained at-10°Cand-20°Cin propylene carbonate contained electrolyte,respectively.In-situ XRD together with XPS and SEM reveal that the NCM622 cycled at-10°Cpresented better structural stability and more intact interface than that of cathodes cycled at 30°C.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°Cafter 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.