Nanofluidic voidless electrode for electrochemical capacitance enhancement in gel electrolyte

Porous electrodes with extraordinary capacitances in liquid electrolytes are oftentimes incompetent when gel electrolyte is applied because of the escalating ion diffusion limitations brought by the difficulties of infilling the pores of electrode with gels. As a result, porous electrodes usually exhibit lower capacitance in gel electrolytes than that in liquid electrolytes. Benefiting from the swift ion transport in intrinsic hydrated nanochannels, the electrochemical capacitance of the nanofluidic voidless electrode (5.56% porosity) is nearly equal in gel and liquid electrolytes with a difference of ~1.8%. In gel electrolyte, the areal capacitance reaches 8.94 F cm⁻² with a gravimetric capacitance of 178.8 F g⁻¹ and a volumetric capacitance of 321.8 F cm⁻³. The findings are valuable to solid-state electrochemical energy storage technologies that require high-efficiency charge transport.