Co(OH)2/MXene composites for tunable pseudo-capacitance energy storage

In our study, Co(OH)2/Ti3C2Tx MXene materials with layered 2D/2D heterojunction structures were synthesized as model systems, and their performance for pseudocapacitive energy storage was inverstigate. The results demonstrated that the coupling of Co(OH)2 and Ti3C2Tx can increase both the redox and intercalation pseudocapacitance of the as-prepared composite materials. Consquently, a total pseudo-capacitance of 153.0 F g−1 can be achieved for the Co(OH)2/Ti3C2Tx sample with a Ti3C2Tx loading of 25 wt%, which is twice of that of the bare Co(OH)2, and an excellent stablility with only 1% decrease in capacitance after 1000 cycles has also been accomplished. Moreover, the quantitative kinetic analysis demonstrated that the dominant pseudocapacitive contribution for the as-prepared Co(OH)2/Ti3C2Tx materials can be tuned from surface capacitance into intercalation pseudocapacitance by adjusting the Ti3C2Tx loading. This work may provide a new approach for designing MXene based pseudo-capacitive electrode materials with better rate capability and stability.