A1掺杂量对正极材料LiNi_(1/3)Co_(2/3-x)A1_xO_2结构和电化学性能的影响

以共沉淀法合成的前驱体Ni_(1/3)Co_(2/3-x)Al_x(OH)_2与低共熔锂盐0.38LiOH·H_2O-0.62LiNO_3制备了锂离子电池正极材料LiNi_(1/3)Co_(2/3-x)Al_xO_2(x=1/12,1/3,1/2,7/12).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,LiNi_(1/3)Co_(2/3-x)Al_xO_2在1/12≤x≤1/3范围内可以保持单一的六方层状a-NaFeO_2结构,当A1掺杂量(x)高于1/3时,会出现杂相.其中,LiNi_(1/3)Co_(1/3)Al_(1/3)O_2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2.88 g·cm~(-3),首次放电容量为151.5 mAh·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120.9 mAh·g~(-1)

Influence of A1 Doping Content on the Structure and Electrochemical Properties LiNi_(1/3)Co_(2/3-x)Al_xO_2

The layerd cathode materials LiNi_(1/3)Co(2/3-x)Al_xO_2(x=1/12, 1/6,1/3,1/2,7/12) for lithium ion battery has been successfully synthesized using eutectic lithium salts of 0.38LiOH · H_2O-0.62LiNO_3 mixed with Ni_(1/3)Co_(1/3)Al_(1/3)(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 LiNi_(1/3)Co_(2/3_x)Al_xO_2 can be maintained as a well-layered α-NaFeO_2 structure in the range of 1/12 ≤x≤ 1/3. At x>l/3, a miscellaneous phase is present. The LiNi_(1/3)Co_(1/3)Al_(1/3)O_2 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.