水杨酸钠和氨水作为络合剂合成LiNi_(0.80)Co_(0.15)Al_(0.05)O_2正极材料

同时采用水杨酸钠和氨水作为络合剂,通过共沉淀控制结晶法合成了Ni_(0.80)Co_(0.15)Al_(0.05)(OH)_2前驱体,然后在750℃下烧结,制备出锂离子电池正极材料LiNi_(0.80)Co_(0.15)Al_(0.05)O_2。通过对混合硫酸盐溶液及Ni-Co-Al-C_7H_5O_3Na-NH_3-H_2O平衡体系作热力学计算分析,结果表明:在混合盐溶液中,Al~(3+)几乎完全被水杨酸根离子络合,在混合盐溶液泵入底液后,又能缓慢释放出Al~(3+)参与共沉淀反应;在共沉淀反应的最佳范围pH=10~11.5,最佳氨水浓度c(NH3)=0.1~0.3 mol/L范围内获得球形Ni_(0.80)Co_(0.15)Al_(0.05)(OH)_2前驱体,以该前躯体合成LiNi_(0.80)Co_(0.15)Al_(0.05)O_2正极材料,0.2 C首次放电比容量达175.1 mAh/g,70次循环后容量保持率为86.7%,具有优异的循环性能。

Synthesis of LiNi0.80Co0.15Al0.05O2with sodium salicylate and ammonia as chelating agent

The cathode material LiNi0.80Co0.15Al0.05O2 was synthesized at 750 ℃ from the precursor of Ni0.80Co0.15Al0.05(OH)2 synthesized with sodium salicylate and ammonia as chelating agent simultaneously by continuous co-precipitation method.The thermodynamic analysis of the mixed salt solution and Ni-Co-Al-C7H5O3Na-NH3-H2O co-precipitation system was carried out.The results demonstrate that Al3+ is nearly completely compounded by salicylate ion in the mixed salt solution while it can be slowly released after pumping into a tank reactor,and the spherical Ni0.80Co0.15Al0.05(OH)2 precursor can be obtained at pH=10-11.5 with 0.1-0.3 mol/L of the ammonia concentration.The cathode material LiNi0.80Co0.15Al0.05O2 synthesized from that precursor has the initial discharge specific capacity of 175.1 mAh/g at 0.2 C and the capacity retention of 86.7％ after 70 cycles at 2.8-4.3 V,exhibiting good cycle performance.