High-performance flexible supercapacitor based on PEDOT:PSS wrapped delaminated Ti3C2Tx composite: experimental and DFT validation

Abstract

Exploring new electrode materials with cyclic stability and energy storage capacity is crucial for high-performance energy storage in portable electronics. Herein, we present PEDOT:PSS (PP)/delaminated MXene (d-Ti₃C₂T_x) binary nanocomposites for electrode material for flexible supercapacitor (FSC). PP/d-Ti₃C₂T_x (1:2 weight ratio, P1M2) on activated carbon cloth results in an excellent specific capacitance of 718.67 F g^-1 at a current density of 3.5 A g^-1 in 1 M H₂SO₄. PEDOT chains wrap the d-Ti₃C₂T_x nanosheets by an opposite electrostatic interaction, while PSS chains act as web-like carrier pathways between two adjacent nanosheets. First principle DFT simulations demonstrate that charge storage in PEDOT:PSS@Ti₃C₂T_x is enhanced compared to PEDOT@Ti₃C₂T_x, which describes the effect of PSS chains in the composite. Computationally obtained absorption spectra align well with experimental results, validating the proposed morphology. To employ the P1M2 electrode for FSC, P1M2-P1M2 symmetric solid-state supercapacitor (SSC) and P1M2-rGO asymmetric solid-state supercapacitor (ASC) have been fabricated using 1 M PVA-H₂SO₄ gel electrolyte. P1M2-P1M2 SSC and P1M2-rGO ASC exhibit a high specific capacitance of 260.23 F g^-1 (0.5 A g^-1) and 176.46 F g^-1 (0.1 A g^-1) receptively. Larger potential window, excellent specific capacitance retention of ∼89% for 5000 GCD cycles, and great performance retention over the bending and twisting conditions make the ASC device a marvelous candidate for the portable energy storage device. The ASC device shows change in specific energy (specific power) from 35.29 W h kg^-1 (240 W kg^-1) to 26.22 W h kg^-1 (1200 W kg^-1). An assembly of three such ASC devices glows a red LED for ∼2 min.