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

Abstract Herein, a novel conducting polymer complex PEDOT:CF3SO2(x)PSS(1‐x) [denoted as S‐PEDOT:CF3SO2(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:CF3SO2(x)PSS(1‐x), the highest value reported so far. An all‐solid‐state supercapacitor assembly with a structure of S‐PEDOT:CF3SO2(x)PSS(1‐x)/H2SO4:polyvinyl alcohol (PVA)/S‐PEDOT:CF3SO2(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:CF3SO2(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.