溶胶-凝胶法制备Li_4Ti_5O_(12)/C复合负极材料及性能研究

Preparation and performance of Li_4Ti_5O_(12)/C composite anode materials by sol-gel method

以醋酸锂、钛酸丁酯为原料,草酸为络合剂和碳源,采用溶胶-凝胶法氮气气氛中合成锂离子电池负极材料Li4Ti5O12/C,研究了锂源过量与否对材料结构和电化学性能的影响。采用XRD、SEM对材料的晶体结构和微观形貌进行表征,采用恒流充放电循环测试对材料的电化学性能进行表征。结果表明：当锂源过量5%时,合成的Li4Ti5O12/C材料为单一的尖晶石结构,且样品粒径较小（约100~150 nm）,有利于锂离子的嵌入与脱出。其在0.2、1.0、2.0 C和5.0 C时的首次放电比容量分别为182.5、162.7、155.7 mAh/g和155.3 mAh/g,且5.0 C倍率下循环50次后仍达153.9mAh/g,表现出较好的高倍率放电性能和循环稳定性。

Li4Ti5O12/C composite anode materials for lithium-ion battery were synthesized in N2 by sol-gel method using lithium acetate and tetrabutyl titanate as raw materials,oxalic acid as chelating agent and carbon source.And the effect of lithium source amount on the structure and electrochemical properties of the as-prepared composites was systematically investigated in this paper.The crystal structure and microstructure were characterized by means of XRD and SEM,and the electrochemical properties of samples were evaluated by constant-current charge-discharge cycling test.The results show that Li4Ti5O12/C composite with 5% excess of lithium source exhibits a phase-pure spinel structure and much smaller particle size（about 100~150 nm）,which is believed to be beneficial for the insertion/deinsertion of lithium ions.It delivers the initial discharge capacities of 182.5,162.7,155.7 mAh/g and 155.3 mAh/g at 0.2,1.0,2.0 C and 5.0 C rates respectively,which can also reach 153.9 mAh/g after 50 cycles at 5.0 C rate,showing excellent high-rate dischargeability and cycling stability.