All-solid state electric double layer capacitor using polymer electrolyte and isotropic high density graphite electrodes

Isotropic high density graphite (HDG) was used as the polarizable electrode of electric double layer capacitors (EDLC) with a solid electrolyte consisting of PEO/LiClO₄([EO]/[Li⁺] = 8:1) at 80 °C or with a gel electrolyte consisting of PEO/ PC/LiClO₄ ([EO]/[PC]/|Li⁺] = 8:8:1) at room temperature. The all-solid state capacitor with HDG electrodes works satisfactorily as a EDLC with a relatively high capacitance, as well as the EDLC with gel electrolyte PEO/PC/LiClO₄. These EDLCs with solid polymer electrolyte PEO/LiClO₄ and gel electrolyte PEO/PC/LiClO₄ show good charge/discharge behavior when charged to 1.5 V at 80 °C and 20 °C, respectively.