Microenvironment Reconstitution‐Induced Collaborative Oxyanions‐Vacancies Engineering for Enhanced High‐Mass‐Loading Energy Storage

Abstract Performance breakthrough of energy‐storage electrodes under commercial‐level mass loading (≥10 mg cm −2 ) are highly pursued but restricted by sluggish mass/charge transfer rates and kinetically unfavorable reaction sites. In response, through electrochemical microenvironment reconstitution, these limitations are broken by engineering synergy between vacancies and oxyanions in the active matrix (Rec‐NiCo Exch ), which showcases a record‐level areal capacitance of 10.9 C cm −2 with a high mass loading of 20 mg cm −2 and a retention of 72% at 100‐fold current density. Such a design further endows the hybrid supercapacitor with an areal capacity of 20.9 C cm −2 and an energy density of 4.6 mWh cm −2 , outperforming most of the benchmark results. Theoretical calculation reveals that in situ evolved oxyanions not only act as the effective adsorption sites but also secure the oxygen vacancies, enabling the potential synergy toward improved electronic conductivity and enhanced reactivity of Ni sites. As a proof‐of‐concept, the as‐assembled quasi‐solid‐state micro‐supercapacitor deliveries an ultrahigh energy density of 111.5 µWh cm −2 and presents great potential in intermittent energy storage by the solar panel‐supercapacitor‐LED system. This work offers insights for constructing commercial‐level energy‐storage electrodes by mastering surface/interface engineering for practical applications.