A Universal Converse Voltage Process for Triggering Transition Metal Hybrids In Situ Phase Restruction toward Ultrahigh-Rate Supercapacitors.

Abstract

Defect engineering holds great promise for precise configuration of electrode materials for dramatically enhanced performance in the field of energy storage, but the high energy/large time cost and lack of control involved in this process represent a serious limit to its use. In response, a low-energy-cost and ultrafast universal converse voltage process is developed to effectively activate the capacitive performance of transition metal compounds integrated on carbon fiber paper, including Co-, Ni-, Mn-, Fe-, and Cr-based hybrids. As a representative example, this process triggers a phase conversion from cobalt hydroxide to electric-field-activated CoOOH (EA-CoOOH), leading to the formation of molecular structure with abundant defects, lattice disorders, and connecting holes, responsible for an enhanced performance within 10 min at room temperature. Moreover, the retained Co²⁺ in EA-CoOOH results in increased activity, confirmed by density functional theory calculations. Consequently, these EA-CoOOH hybrids deliver a capacitance value of 832 F g^-1 at a current density of 1 A g^-1 and exhibit a retention rate up to 78% (649 F g^-1 ) at a super-large current density of 200 A g^-1 . This technology paves a way for ultrafast configuration/modulation of defects on advanced materials toward application in the fields of energy and catalysis.