A Voltage-Stabilizing MXene Additive Electrolyte Mitigates Interference From External Force on the Charge-Discharge Process for Multifunctional Hybrid Structural Supercapacitors.

Abstract

In structural energy storage devices (SESDs) that simultaneously store electrochemical energy and bear mechanical loading, the external force will normally affect the electrochemical performance of SESDs. One example is that, under cyclic bending stress, voltage ripples emerge in charge-discharge curves, which cause voltage instability. In this study, we demonstrate that these voltage ripples originate from spatially heterogeneous electric field distribution within the mechanically deformed region. By using polarized electric fields formed through hydrogen bonding networks in MXene additive electrolyte, we can effectively homogenize the distribution of the electric field, thereby attenuating voltage ripples and smoothing the voltage curves. Moreover, the uniform electric field distribution promotes uniform Zn deposition and extends the device lifespan. As a result, the fabricated Zn-ion-based structural hybrid supercapacitor (CSHS) with MXene additive electrolyte exhibits a capacity retention of 93.6% after 10 000 three-point bending cycles at a strain of 0.5%, much higher than that of CSHS without the addition of MXene (80.4%). The investigation into the suppression of voltage ripples of SESDs paves a viable way to design high-performance structural power sources capable of exhibiting stable voltage under mechanical loading.