Large Capacitance Enhancement Achieved via Tuning Electrode/Electrolyte Thickness of Graphene Oxide‐Based All‐Solid‐State Supercapacitors

Graphene oxide-based all-solid-state supercapacitors (GO ASSCs) provide a to-the-point opportunity of integrating miniaturized energy storage devices on a single chip with operation-ability and safety superiority over liquid electrolyte-based SCs, yet their capacitance needs to be improved. Based on the lamellar MXene-GO ASSC structure energy density of the GO ASSCs can be brought up to the level comparable to their counterparts using liquid electrolytes via simple tuning the MXene/GO thickness. During analyzing how the GO and MXene thickness affects the electrochemical performance, a major paradox is noticed between the high capacitance of up to two hundreds of farads per gram achievable with specific MXene/GO thickness combination, and its seemly slow diffusion kinetics. In situ pressure test is designed, and a quick capacitance saturation validated enhanced "charge storage efficiency" of the specific MXene/GO thickness combination, further revealing a possible delicate balance acquired between the solid electrolyte and the electrodes to break the restriction on ion diffusion. The findings should provide a straightforward solution in achieving high capacitance performance for the ASSCs using GO solid electrolyte and MXene or other pseudocapacitive electrode materials.