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Abstract In recent years, rechargeable aqueous zinc‐ion batteries (ZIBs) have received much attention. However, the disproportionation effect of Mn 2+ seriously affects the capacity retention of ZIBs during cycling. Here, the capacity retention of the Mn 3 O 4 cathode is improved by effective valence engineering. The valence engineering of Mn 3 O 4 is caused by bulk oxygen defects, which are in situ derived from the Mn‐metal organic framework during carbonization. Bulk oxygen defects can change the (MnO 6 ) octahedral structure, which improves structural stability and inhibits the dissolution of Mn 2+ . The ZIB assembled from bulk oxygen defects Mn 3 O 4 @C nanorod arrays (O d ‐Mn 3 O 4 @C NA/CC) exhibits an ultra‐long cycle life, reaching 84.1 mAh g −1 after 12 000 cycles at 5 A g −1 (up to 95.7% of the initial capacity). Furthermore, the battery has a high specific capacity of 396.2 mAh g −1 at 0.2 A g −1 . Ex situ characterization results show that initial Mn 3 O 4 is converted to ramsdellite MnO 2 for insertion and extraction of H + and Zn 2+ . First‐principles calculations show that the charge density of Mn 3+ increases greatly, which improves the conductivity. In addition, the flexible quasi‐solid‐state ZIB is successfully assembled using O d ‐Mn 3 O 4 @ C NA/CC. Valence engineering induced by bulk oxygen defects can help develop advanced cathodes for aqueous ZIB.
Tan et al. (Thu,) studied this question.