Highly Stable Supercapacitors Enabled by a New Conducting Polymer Complex PEDOT:CF3 SO2(x) PSS(1-x)

Abstract

Herein, a novel conducting polymer complex PEDOT:CF₃ SO_2(x) PSS_(1-x) [denoted as S-PEDOT:CF₃ SO_2(x) PSS_(1-x) , where PEDOT is poly(3,4-ethylenedioxythiophene) and PSS is poly(styrene sulfonate)], is fabricated with the assistance of zinc di[bis(trifluoromenthylsulfonyl) imide][Zn(TFSI)₂ ] (CFE). The introduction of CF₃ SO₂ ^- group is expected to bring better stability of PEDOT:CF₃ SO₂ than PEDOT:PSS due to its strong Coulomb force. Electrochemical measurement shows that a high specific capacitance of 194 F cm^-3 was achieved from the novel complex S-PEDOT:CF₃ SO_2(x) PSS_(1-x) , the highest value reported so far. An all-solid-state supercapacitor assembly with a structure of S-PEDOT:CF₃ SO_2(x) PSS_(1-x) /H₂ SO₄ :polyvinyl alcohol (PVA)/S-PEDOT:CF₃ SO_2(x) PSS_(1-x) shows a record specific capacitance of 70.9 F cm^-3 and a maximum energy density of 6.02 mWh cm^-3 at a power density of 397 mW cm^-3 . This supercapacitor device demonstrates excellent electrochemical stability with a capacitance retention rate of 98 % after 10 000 cycles and extreme air stability of 96 % capacitance retention rate after 10 000 cycles, even if the device is exposed to air over 2880 h, much better than that of PEDOT:PSS based supercapacitors. Excellent capacitance can be achieved from PEDOT:CF₃ SO_2(x) PSS_(1-x) electrode under electrolyte-free conditions. This work provides a novel method for high performance stable supercapacitors and may pave the way for the commercialization of PEDOT based supercapacitors.

Keywords: conducting polymers; electrolyte-free; ionic liquids; stability; supercapacitors.