<p>Despite the development of various pseudocapacitive materials, full-cell pseudocapacitors have yet to surpass the power density of conventional electric double layer capacitors, primarily due to the lack of high-rate positive pseudocapacitive materials. This work reports a solid-state conjugated polyelectrolyte that achieves high-rate charge storage as a positive electrode, facilitated by a co-ion desorption mechanism. The conjugated polyelectrolyte retains 70% of its capacitance at 100 A g<sup>−1</sup> with a mass loading of 2.8 mg cm<sup>−2</sup> and exhibits a long cycling life of 100,000 cycles in a Swagelok cell configuration. Increasing the electrode thickness fourfold has minimal impact on ion diffusivity and accessibility, yielding a high areal capacitance of 915 mF cm<sup>−2</sup>. When paired with a high-rate negative pseudocapacitive electrode Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>, the device leverages the redox-active potentials of both materials, achieving a device voltage of 1.5 V and supports operation rates up to 10 V s<sup>−1</sup> or 50 A g<sup>−1</sup>. This configuration enables the pseudocapacitor to deliver an areal power of 160 mW cm<sup>−2</sup>, while significantly increasing the areal energy (up to 71 μWh cm<sup>−2</sup>). The high areal performance, combined with the additive-free and water-based fabrication process, makes pseudocapacitors promising for on-chip and wearable energy storage applications.</p>

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Aqueous asymmetric pseudocapacitor featuring high areal energy and power using conjugated polyelectrolytes and Ti3C2Tx MXene

  • Benjamin Rui Peng Yip,
  • Chaofan Chen,
  • Yan Jiang,
  • David Ohayon,
  • Guillermo C. Bazan,
  • Xuehang Wang

摘要

Despite the development of various pseudocapacitive materials, full-cell pseudocapacitors have yet to surpass the power density of conventional electric double layer capacitors, primarily due to the lack of high-rate positive pseudocapacitive materials. This work reports a solid-state conjugated polyelectrolyte that achieves high-rate charge storage as a positive electrode, facilitated by a co-ion desorption mechanism. The conjugated polyelectrolyte retains 70% of its capacitance at 100 A g−1 with a mass loading of 2.8 mg cm−2 and exhibits a long cycling life of 100,000 cycles in a Swagelok cell configuration. Increasing the electrode thickness fourfold has minimal impact on ion diffusivity and accessibility, yielding a high areal capacitance of 915 mF cm−2. When paired with a high-rate negative pseudocapacitive electrode Ti3C2Tx, the device leverages the redox-active potentials of both materials, achieving a device voltage of 1.5 V and supports operation rates up to 10 V s−1 or 50 A g−1. This configuration enables the pseudocapacitor to deliver an areal power of 160 mW cm−2, while significantly increasing the areal energy (up to 71 μWh cm−2). The high areal performance, combined with the additive-free and water-based fabrication process, makes pseudocapacitors promising for on-chip and wearable energy storage applications.