煅烧温度对锂离子正极材料Li[Ni_(0.475)Mn_(0.475)Co_(0.05)]O_2结构和电化学性能的影响 ; Calcined Temperatures Influence on Synthesis and Electrochemistry Charactarization of Li[Ni_(0.475)Mn_(0.475)Co_(0.05)]O_(2) for Li-ion Batteries