All-Solid-State Stretchable Pseudocapacitors Enabled by Carbon Nanotube Film-Capped Sandwich-like Electrodes

Stretchable pseudocapacitors have demonstrated perspective potential as the power sources for stretchable/flexible electronics. However, one of the main limitations is to increase the mass loading of pseudocapacitive materials while maintaining high electrochemical performance. Therefore, the architectural design of stable and stretchable electrodes with a high mass loading of pseudocapacitive materials becomes critical and desirable. Here we report an all-solid-state sandwich-like stretchable pseudocapacitor, which overcomes the limitation of maximum loading of active pseudocapacitive materials and exhibits excellent structural and electrochemical stabilities, giving rise to outstanding cycling stability and rate capability. The enhanced pseudocapacitive performances result from the synergistic effect in the all-solid-state and binder-free structure: (1) faster ion diffusion rates and charge transport at electrode/electrolyte interfaces and (2) improved mechanical property to mitigate the electrode degradation caused by ion insertion/extraction during charge-discharge and mechanically stretching-releasing cycles. This novel component-level design offers an effective way to improve the electrochemical performance of stretchable pseudocapacitors, and more importantly, this concept can be extended for improving the performance of other electrochemical systems such as stretchable supercapacitors, lithium-ion batteries, lithium-sulfur batteries, and solar cells, and accelerate its applications for wearable and implantable electronics.