用于锂离子电容器的多孔炭黑材料

Porous carbon black for high performance lithium-ion capacitors

锂离子电容器(LICs)是基于二次离子电池和超级电容器研究基础上提出的新型储能器件。目前,LICs负极存在电化学动力学行为缓慢的难题,这与正极快速动力学特性并不匹配,极大地限制了LICs的倍率和循环性能,研发兼具低成本、倍率/循环性能好的炭负极材料已成为研究热点。本研究采用导电性好、价格低廉的工业化产品炭黑(CB)为前驱体,采用KOH活化法制备了多孔炭黑(CB-KOH),其具有极佳的倍率性能和循环性,在2.0 A/g与5.0 A/g电流密度下分别具有274.5 mAh/g和194.9 m Ah/g的储锂容量,2.0 A/g电流密度下循环1000圈后,其容量保持率为96.4%,每圈衰减率仅为0.0036%。非原位XRD结果表明,CB-KOH在充放电过程中的膨胀率明显低于CB,这有利于保持其结构稳定性,提升循环性能。采用生物质茄子活性炭(AC)为正极材料,CB-KOH为负极材料,组装的锂离子电容器CB-KOH//AC功率密度在2579.3 W/kg和5340.6 W/kg时,其能量密度仍然分别能达到75.4 Wh/kg和70.7 Wh/kg,兼具高能量密度和高功率密度,具备实用化前景。

Lithium-ion capacitors(LICs)are the novel energy storage devices which were proposed on the basis of studying the lithium-ion batteries(LIBs)and supercapacitors.Nevertheless,the problems that anode materials of LICs possess the slow kinetics behaviors on the electrochemical process cause the appearances of the incompatibility among the positive and negative electrodes of the LICs,which significantly restricts the cycling and rate performances of LICs.Therefore,developments of anode materials having excellent kinetics behaviors on the electrochemistry process are becoming the hot research topics more than ever before.The activated CB-KOH is prepared with carbon black(CB),a cheap industrial product as the raw material,and KOH as the activate agent.It is observed that the activated CB-KOH materials possess the porous structures and improved rate and cycling performances,which achieves a reversible capacity of 274.5 mAh/g at 2.0 A/g and 194.9 mAh/g at 5.0 A/g,as well as good cycling stability of 96.4%with only 0.0036%degradation per cycle within 1000 cycles at 2.0 A/g.Ex-situ XRD measurements show that CB-KOH owns the smaller volume expansion rate than CB in the charge-discharge process,indicating that CB-KOH materials exhibit the more excellent structural stability than CB,which is beneficial to improve cycling performances of CB-KOH materials.Finally,the biomass activated carbon as positive electrode and CB-KOH as negative electrode were used to assemble LICs which are originally named as CB-KOH//AC.It is surprisingly observed that the energy densities are achievable to 75.4 Wh/kg and 70.7 Wh/kg,when the power densities are adjusted at 2579.3 W/kg and 5340.6 W/kg,respectively.Based on the fact that CB is the extremely popular commodities,it is considered that this study can provide a reference for developing anode materials of LICs.