In situ synthetic C encapsulated δ-MnO 2 with O vacancies: A versatile programming in bio-engineering.

In this study, we successfully synthesized a δ-MnO ₂ cathode with O vacancies, encapsulated by C derived from pyromellitic acid, using a facile hydrothermal method followed by annealing in an Ar atmosphere. The cathode's structural stability and charge transfer kinetics are enhanced by inhibiting the formation of the by-product Zn ₄ SO ₄ (OH) ₆ ·4H ₂ O, regulating the Mn valence state, and suppressing the Jahn-Teller effect through the synergy of C encapsulation and O vacancies. This results in remarkable electrochemical performance, including a large capacity of 421.2 mAh g ^-1 at 0.1 A g ^-1 , a high specific energy density of 595.53 Wh kg ^-1 , and exceptional long-cycle life stability with 90.88% over 4000 cycles at 10 A g ^-1 , together with superior coulombic efficiency (∼100%) in pure ZnSO ₄ electrolyte. Moreover, the cathode materials demonstrate specific antitumor efficacy. In brief, this work introduces an in situ synthetic C encapsulated δ-MnO ₂ with O vacancies expected to be applied in both large-scale energy storage and biomedicine.
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