Mg^(2+)掺杂对sol-gel法合成锂离子电池材料Li_3V_2(PO_4)_3的影响

Performance and structure of Mg^(2+)-doped-Li_3V_2( PO_4)_3 cathode material for lithium-ion batteries

在磷酸钒锂材料中掺杂Mg2+,Mg2+取代锂位,其化学式可以写为(Li1-xMgx/2)3V2(PO4)3,Mg(OH)2作为镁源,按化学反应方程式中化学计量比称取LiOH.H2O,NH4H2PO4,V2O5,Mg(OH)2(x=0.01、0.05、0.1)和柠檬酸,其中柠檬酸用量为n(V)∶n(柠檬酸)=2∶2,煅烧温度为700℃,煅烧时间为8 h,合成了(Li1-xMgx/2)3V2(PO4)3正极材料。研究了Mg2+掺杂量对材料性能的影响,考察了x=0、0.01、0.05、0.1四种情况。结果显示,x=0.05时材料具有较好的充放电性能。在2.7～4.5 V电压范围内进行充放电循环测试,0.05 C充放电倍率下,其首次放电比容量为145 mAh/g,库仑效率高达90%以上,0.1 C循环20次后,放电比容量仍为131 mAh/g;0.2 C循环时,首次放电比容量为140 mAh/g左右,20次循环后仍为130 mAh/g以上;0.5 C循环20次后,放电比容量为104 mAh/g。

Li3V2（PO4）3 doped with Mg2＋ particles was successfully synthesized by sol-gel method using LiOH.H2O,NH4H2PO4,V2O5,H2O2,Mg（OH）2 and citric acid as the raw material.Using Mg2＋ to replace the lithium-bit,its chemical for mula could be written as（Li1-xMgx/2）3V2（PO4）3.The citric acid dosage was n（V）∶n（citric acid）=2∶2,calcination temperature was 700 ℃,and calcining time was 8 h.The examined four cases at x = 0,0.01,0.05,0.1.The results show that when x= 0.05,the material has a good charge-discharge performance.Controlling the charge and dis-charge voltage range from 2.7 to 4.5 V,at 0.05 C,its first discharge capacity is up to 145 mAh/g.At 0.1 C,after 20 cycles,the discharge capacity is up to 131 mAh/g.At 0.05 C,its first discharge capacity is up to 140 mAh/g and at 0.5 C,its discharge capacity is up to 104 mAh/g after 20 cycles.