電気二重層キャパシタ性能に対する電極カーボン材のミクロ孔およびメソ孔の寄与

抄録

Performance of electric double layer capacitors (EDLCs) was studied by using different microporous and mesoporous carbons in positive and negative electrodes (symmetric and asymmetric EDLCs) in non-aqueous and aqueous electrolytes (1M TEMABF₄/PC and 1M H₂SO₄, respectively). Microporous carbons were selected from commercially available activated carbons and mesoporous carbons from laboratory-made ones. Asymmetric EDLCs consisting of microporous carbon AC-5 and different mesoporous carbons XX in either the positive or negative electrode (AC-5/XX and XX/AC-5) showed a predominant contribution of the negative electrode, where cations of electrolyte are adsorbed, to capacitance and rate performance. Contributions of the surface due to micropores and that due to other large pores to the EDLC capacitance were separately evaluated as a function of current density for the charge/discharge cycle in two electrolytes. The contribution of microporous surface, C_micro., is smaller than that of the surface of other large pores, C_ext., depending more markedly on current density during the charge/discharge cycle. The values of C_ext./C_micro. are in the range 2.4~2.8 in H₂SO₄, but 4.3~7.2 in TEMABF₄/PC. C_micro. in TEMABF₄/PC is smaller than that in H₂SO₄, suggesting a smaller contribution of micropores to capacitance in TEMABF₄/PC.