复合导电剂对锂离子电池性能的影响

将石墨烯(rGO)、导电石墨(SP)和碳纳米管(CNT)复合,制得rGO/SP、CNT/rGO和CNT/SP复合导电剂,用来改善锂离子电池正极的导电性能。采用XRD、SEM、电化学阻抗谱及恒流放电等测试,分析导电剂的形貌及电池的性能。导电剂种类对于电池电化学性能的影响较大。添加CNT/rGO制备的正极粉末电导率最高,可达到2.305 S/cm,与混合正极材料m(LiNi 0.80 Co 0.15 Al 0.15 O 2)∶m(LiMn 2O 4)=7∶3]相比,提高了27倍。采用CNT/rGO复合导电剂制备的18650型混合正极材料锂离子电池,单体电池内阻最小(13.5 mΩ)、化成容量最高(1856.1 mAh)。在4.2~2.5 V充放电,以10.00 C高倍率放电时,平台电压最高(3.2 V)、放电容量最高(1764.5 mAh);以1.00 C倍率循环600次,rGO/SP、CNT/SP和CNT/rGO复合导电剂制备的电池容量保持率分别为93.70%、94.36%和95.13%。

Effects of mixture conductive agents on the performance of Li-ion battery

Graphene(rGO)was combined with conductive carbon Super P(SP)and carbon nanotube(CNT)to obtained rGO/SP,CNT/rGO and SP/CNT mixture conductive agent,in order to improve the conductive performance of the cathode of Li-ion battery.XRD,SEM,electrochemical impedance spectroscopy and galvanostatic charge-discharge tests were used to analyze the morphology of conductive agents and the performance of the battery.The kind of conductive had great influence on the electro-chemical performance of the battery.The blended cathode materialm(LiNi 0.80 Co 0.15 Al 0.15 O 2)∶m(LiMn 2O 4)=7∶3]with CNT/rGO had a highest electrical conductivity with up to 2.305 S/cm,which was 27 times as much as pure blended cathode material.The 18650 type Li-ion battery assembled with CNT/rGO mixture conductive agent exhibited the smallest internal resistance(13.5 mΩ)and the highest formation capacity(1856.1 mAh).It delivered the highest voltage plate(3.2 V)and discharge capacity of 1764.5 mAh at 10.00 C in 4.2-2.5 V.The capacity retention ratio of the Li-ion battery assembled with rGO/SP,CNT/SP and CNT/rGO mixture conductive agent were 93.70%,94.36%and 95.13%at 1.00 C in 4.2-2.5 V for 600 cycles,respectively.