Covalent Bonding Homo-All-in-One Configuration Enables a Flexible Supercapacitor with Superior Mechanical Durability Exceeding 50 000 Cyclic Deformations

Abstract

All-in-one configured supercapacitor holds great promise in addressing cyclic deformation-induced relative displacement and delamination among electrode/electrolyte/electrode faced by the conventional laminated supercapacitor, but its interfacial interactions among heterogeneous electrode/electrolyte/electrode only depend on weak secondary or physical bonds, leading to insufficient mechanical durability. Herein, a concept of covalent bonding homo-all-in-one configuration is proposed to construct strong covalent bonding interfaces among electrode/electrolyte/electrode comprising homomatrix polymer PVA through simultaneous chemical cross-linking of the homomatrixes and interfaces, thereby achieving mechanically durable homo-all-in-one supercapacitors (cPMP/cPVA/cPMP HSCs). Based on the adjustment in cross-linking time, seamlessly integrated interfaces form in the cPMP/cPVA/cPMP HSCs, which achieve high mechanical properties, remarkable interfacial bonding strength, and low interfacial charge transfer resistance. In sharp contrast to conventional laminated supercapacitors, the cPMP/cPVA/cPMP HSCs deliver superior areal capacitance of 268.8 mF cm–2 at 5 mV s–1 and unexpected cyclic stability with capacitance retention of 104% after 20 000 charge–discharge cycles. It is highlighted that the cPMP/cPVA/cPMP HSCs reach an unprecedented level of mechanical durability with capacitance retention of 103% and 101% exceeding 50 000 bending and twisting cycles, respectively. Furthermore, the cPMP/cPVA/cPMP HSCs are demonstrated to light up a red LED bulb under flat, bending, twisting, and even folding conditions. Those findings are intended to lead to an advanced design trend for the development of covalent bonding homo-all-in-one configured supercapacitors toward flexible and wearable electronic applications.