Highly Stable Supercapacitors Enabled by a New Conducting Polymer Complex PEDOT:CF3SO2(x)PSS(1‐x)

Stable in air: A novel conducting polymer complex PEDOT:CF₃SO_2(x)PSS_(1-x) has been prepared with the highest capacitance value of 194 F cm⁻³. Supercapacitors based on this complex demonstrate a record capacitance of 70.9 F cm⁻³, a maximum energy density of 6.02 mWh cm⁻³, as well as excellent electrochemical stability and air stability.

Abstract

Herein, a novel conducting polymer complex PEDOT:CF₃SO_2(x)PSS_(1-x) [denoted as S-PEDOT:CF₃SO_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 CF₃SO₂ ⁻ group is expected to bring better stability of PEDOT:CF₃SO₂ 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:CF₃SO_2(x)PSS_(1-x), the highest value reported so far. An all-solid-state supercapacitor assembly with a structure of S-PEDOT:CF₃SO_2(x)PSS_(1-x)/H₂SO₄:polyvinyl alcohol (PVA)/S-PEDOT:CF₃SO_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:CF₃SO_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.

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