以硝基甲烷和水的混合溶剂制备聚丙烯腈(PAN)静电纺丝前驱液.通过非良溶剂在静电纺丝过程中的致孔作用,得到大孔结构PAN静电纺丝纤维.通过控制混合溶剂中水含量,可以得到不同孔隙结构的PAN静电纺丝纤维.然后通过碳化、活化过程得到柔性自支撑大孔结构PAN基超细碳纤维.表观形貌、孔隙及比表面积分析和电化学性能测试等结果显示:当混合溶液中硝基甲烷和水的体积比为95:5时,水具有良好的助溶剂和致孔剂作用,此条件下制备的PAN基超细碳纤维具有较好的孔隙结构、BET比表面积和良好的综合电化学性能(内阻0.43 Ω,能量密度7.7 Wh·kg-1,功率密度11.1×103W·kg-1).

以嵌锂过渡金属氧化物（锂盐）和双电层储能材料活性炭（AC）为电极活性物质,制备LiMn 2 O 4 -AC||AC、LiFePO 4 -AC||AC、LiMn 2 O 4 -AC|Li 4 Ti 5 O 12 -AC、LiFePO 4 -AC||Li 4 Ti 5 O 12 -AC电池-电容器。通过恒电流充放电、循环伏安以及交流阻抗等对其电化学性能进行研究。结果显示:电池-电容器在低工作电压段,电荷主要以双电层储能形式存储于活性炭电极;在高工作电压段电荷主要以锂离子插嵌-脱嵌形式存储于嵌锂过渡金属氧化物。锂盐和AC结合可以有效提高电池-电容器的工作电压、能量密度,同时又具有较好的功率特性。其中LiFePO 4 -AC|Li 4 Ti 5 O 12 -AC具有较好的综合电化学性能,当电压为3.2 V时,能量密度为124.6 Wh·kg –1 ,功率密度为461.7 W·kg –1 ,内阻为2.2?,充放电效率为93.1%。

This paper investigates the relationship between structure and electrochemical performance of reduced graphene oxide (RGO) prepared via heat treatment and chemical reduction method. Structure and morphology of RGO was characterized by means of Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and Brunauer-Emmett-Teller. Electrochemical performance of RGO electrode supercapacitor was investigated in the organic electrolyte by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance. The results show heat treatment RGO has high graphitization degree, less surface oxygen-containing groups, good charge-discharge efficiency and stable life cycle. The chemical reduced RGO has single-graphene structure, high specific surface area, high specific capacitance and low internal resistance. The ascorbic acid reduction RGO exhibits good comprehensive electrochemical performance: Its specific capacitance was 220.7 F g(-1), internal resistance was 3.0 Omega and charge-discharge efficiency was 97.0% after 2000 cycles of charging/discharging tests. Copyright (C) 2016 John Wiley & Sons, Ltd.

Thermally reduced graphene oxide (RGO) electrochemically activated by a quaternary alkyl ammonium-based organic electrolytes/activated carbon (AC) electrode asymmetric capacitor is proposed. The electrochemical activation process includes adsorption of anions into the pores of AC in the positive electrode and the interlayer intercalation of cations into RGO in the negative electrode under high potential (4.0 V). The EA process of RGO by quaternary alkyl ammonium was investigated by X-ray diffraction and electrochemical measurements, and the effects of cation size and structure were extensively evaluated. Intercalation by quaternary alkyl ammonium demonstrates a small degree of expansion of the whole crystal lattice (d002) and a large degree of expansion of the partial crystal lattice (d002) of RGO. RGO electrochemically activated by bis-spiro quaternary alkyl ammonium in propylene carbonate/AC asymmetric capacitor exhibits good activated efficiency, high specific capacity, and stable cyclability.

Imbalanced supercapacitor was constructed by using various ratio of activated carbon (AC) of positive to negative electrode. The electrochemical behavior of imbalanced supercapacitor was investigated using 1.0 M spiro-(1,1′)-bipyrrolidinium tetrafluoroborate electrolyte in propylene carbonate. The results showed that there are some factors that influenced the imbalanced supercapacitor with different AC ratio of positive to negative electrode, the utilization of AC, electrode potential distribution, and life cycle. The imbalanced supercapacitor with an AC weight ratio of 80 : 120 of positive to negative electrode has an average potential distribution in each electrode, and it revealed the best electrochemical performance: specific capacitor was 39.6 F·g−1, while the charge-discharge efficiency was 97.2% after 2000 life cycle tests.