共沉淀法制备LiNi_(0.5)Mn_(1.5)O_4正极材料及其性能

Performance of LiNi_(0.5)Mn_(1.5)O_4 cathode material synthesized by coprecipitation method

采用共沉淀法制备镍锰复合氢氧化物沉淀,然后与LiOH·H_2O混合,空气中800℃煅烧18h,并500℃短时间退火处理5h得到高电压正极材料LiNi_(0.5)Mn_(1.5)O_4。通过X射线衍射光谱法(XRD),扫描电子显微镜法(SEM)和恒电流充放电测试对样品的物相、形貌和电化学性能进行了表征。合成的LiNi_(0.5)Mn_(1.5)O_4具有立方尖晶石结构,结晶性良好,颗粒粒径均匀,为200～300nm。电化学测试表明:样品存在4.7V附近的电压平台,在0.5C的较大放电电流下,首次充电容量为141.0 mAh/g,首次放电容量为122.9 mAh/g,80次循环后样品的容量保持率为97.7%,且经过活化后每个循环的库仑效率都超过了98%,具有极其优秀的循环稳定性和充放电的可逆性。

The composite hydroxid of nickel and manganese was prepared by the coprecipitation method.LiNi0.5）Mn1.5O4 was synthesised by firing the mixture of the prepared composite hydroxid and LiOH- H2O at 800℃ for 18 h and then annealing at 500 ℃ for 5 h in air.The phase,morphology and electrochemical properties of the sample were characterized by XRD,SEM and constant current charge-discharge tests. The synthesized LiNi0.5）Mn1.5O4belonging to cubic phase was a spinel structure with clearly defined shape and particle size of 200-300 nm. Electrochemical tests show that the synthesized LiNi0.5）Mn1.5O4 presents only one plateau near 4.7 V and the charge and discharge capacity are 141.0 mAh/g and 122.9 mAh/g, respectively. After 80 cycles, the capacity retention rate of the sample discharged at 0.5 C is 97.7%. And its coulombic efficiency of every cycle is above 98.5% through activation. The prepared LiNi0.5）Mn1.5O4has very excellent cycle stability and charge-discharge reversibility.