In aqueous rechargeable zinc–manganese dioxide batteries (ZMBs), some irreversible side reactions, such as Mn2+ dissolution, often lead to capacity fading over cycling. These side reactions play a crucial role in the capacity and cycle performance of the battery. The implementation of a bionic electrode microskin (EMS) composed of collagen hydrolysate to convert the irreversible side reactions into reversible reactions is reported. The proposed EMS effectively adsorbs and confines the Mn2+ ions around the cathode through van der Waals forces, hydrogen bonds, and/or ionic interactions, which makes the MnO2/Mn2+ reactions reversible during the charge/discharge process. Such Mn2+ dissolution reactions, with an ultrahigh theoretical capacity (617 mAh g‐1), contribute a large amount of capacity, ≈44% of the total specific capacity at a low scan rate. Based on these fundamental findings, the assembled ZMBs with an EMS display an unprecedented discharge capacity of 415 mAh g‐1 at 20 mA g‐1, which overcomes the theoretical capacity (308 mAh g‐1) limitation of the Zn2+ intercalation mechanism. More significantly, the EMS on all α‐, β‐, and γ‐MnO2 cathodes exhibits similar high capacity beyond the theoretical capacity of Zn intercalation and capacity retention enhancement after 3000 cycles.