高密度球形LiNi_(0.8)Co_(0.2)O_2的制备及性能

Preparation and characterization of high density spherical LiNi_(0.8) Co_(0.2 ) O _2

采用控制结晶法合成球形 β- Ni0 .8Co0 .2 (OH) 2 ,与L i OH.H2 O 混合 ,在 75 0℃通 O2 热处理 8h 合成球形L i Ni0 .8Co0 .2 O2 粉末。用 X光衍射和扫描电镜分析对 β- Ni0 .8Co0 .2 (OH) 2 和 L i Ni0 .8Co0 .2 O2 粉末的结构进行了表征。充放电测试表明该球形 L i Ni0 .8Co0 .2 O2 正极材料具有优良的电化学性能 :首次充电比容量为 2 17m A.h.g- 1 ,放电比容量为172 m A.h.g- 1 ,5 0次充放电循环后保持初始放电比容量的97.5 %。该球形 L i Ni0 .8Co0 .2 O2 粉末的振实密度高达 2 .8g.cm- 3,远高于一般非球形 L i Ni0 .8Co0 .2 O2 正极材料。高密度球形 L i Ni0 .8Co0 .2 O2 正极材料用于锂离子电池可以显著提高电池的能量密度。

Spherical β Ni 0.8 Co 0.2 (OH) 2 powders were prepared using a “controlled crystallization” method. The spherical LiNi 0.8 Co 0.2 O 2 powders were synthesized by sintering the β Ni 0.8 Co 0.2 (OH) 2 precursor and LiOH·H 2O in oxygen at 750℃ for 8h. The β Ni 0.8 Co 0.2 (OH) 2 and LiNi 0.8 Co 0.2 O 2 structures were characterized by XRD and SEM. Electrochemical tests of the charge discharge process show that the spherical LiNi 0.8 Co 0.2 O 2 cathode material has excellent electrochemical performance. The cathode material had a high initial charge capacity of 217mA·h·g -1 and a discharge capacity of 172 mA·h·g -1 with retention of more than 97.5% after 50 cycles. The material tap density is about 2.8g·cm -3 , which is remarkably higher than the non spherical LiNi 0.8 Co 0.2 O 2 powders. The high density spherical LiNi 0.8 Co 0.2 O 2 cathode material can be used in lithium secondary batteries to greatly increase the batteries' energy density.