Al掺杂量对正极材料LiNi_(1/3)Co_(2/3-x)Al_xO_2结构和电化学性能的影响

以共沉淀法合成的前驱体Ni1/3Co2/3-xAlx(OH)2与低共熔锂盐0.38LiOH·H2O-0.62LiNO3制备了锂离子电池正极材料LiNi1/3Co2/3-xAlxO2(x=1/12,1/6,1/3,1/2,7/12).采用X射线衍射(XRD)、扫描电镜(SEM)和电化学性能测试对其结构、形貌和电化学性质进行表征.结果表明,LiNi1/3Co2/3-xAlxO2在1/12≤x≤1/3范围内可以保持单一的六方层状α-NaFeO2结构,当Al掺杂量(x)高于1/3时,会出现杂相.其中,LiNi1/3Co1/3Al1/3O2结晶程度最高,阳离子混排效应最小,并且颗粒小而均匀,振实密度可以达到2.88g·cm-3,首次放电容量为151.5mAh·g-1,循环50次后放电容量保持在91.4%,在1C和2C倍率下放电容量仍可达到133.7和120.9mAh·g-1.

Influence of Al Doping Content on the Structure and Electrochemical Properties of LiNi1/3Co2/3-xAlxO2

The layerd cathode materials LiNi1/3Co2/3-xAlxO2 (x=1/12, 1/6, 1/3, 1/2, 7/12) for lithiumion battery has been successfully synthesized using eutectic lithium salts of 0.38LiOH·H2O-0.62LiNO3 mixed with Ni1/3Co1/3Al1/3(OH)2 as a precursor. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical performance tests. Results show that the LiNi1/3Co2/3 -xAlxO2 can be maintained as a well-layered α-NaFeO2 structure in the range of 1/12≤x≤1/3. At x>1/3, a miscellaneous phase is present. The LiNi1/3Co1/3Al1/3O2 products have the highest crystallinity, the least cation mixing effect and the most uniform particle size with a tap-density of 2.88 g·cm-3. Additionally, the initial discharge capacity of the product was 151.5 mAh·g -1 and after 50 cycles, 91.4%of the initial discharge capacity was maintained. The reversible capacities of the products are 133.7 and 120.9 mAh·g-1 at 1C and 2C discharge rates, respectively.