Although Mn²⁺ additives alleviate the dissolution issue of Mn-based cathodes in aqueous zinc–ion batteries (ZIBs), problems including complex side reactions and abnormal capacity fluctuation pose new challenges for their large-scale applications. In virtue of manganese oxide based on preeminent cation-pillar engineering, we elaborate the origin of capacity fluctuation, which is found to be correlated with the unique Mn²⁺ behavior. For the first time, we figure out new metrics such as effective cycling percentage (η) and maximum Mn²⁺ contribution ratio (ε) to reappraise the electrochemical performance of the current Mn-based ZIBs via a new capacity evaluation protocol, i.e., Mn-based competitive capacity evolution (Mn-CCE). The universality of the protocol and its metrics were further verified via quantitative analyses of the reported Mn-based ZIBs. More significantly, the failure of Mn-based electrodes is demonstrated to be rescuable via facile acid treatment, which is expected to quintuple the lifespan of batteries. The findings can provide new insights to understand the electrochemical behaviors, serve as the assessment criteria, and further guide the development of Zn/Mn-related devices for practical applications.

Although sulfate- and sulfonate-based electrolytes have been widely used in the study of aqueous zinc-ion batteries (AZIBs), discrepancies in the faradaic reaction kinetics of cation interfacial chemistry including in Mn²⁺ redox reactions and Zn deposition are observed in these two systems, the mechanism of which is still unclear. Herein, through focusing on the electrolyte solvation structure, we constructed a specific adsorption model involving the coexistence of anions, cations, and water molecules at the electrode/electrolyte interface. Distinguished from the traditional investigation of isolated adsorbed particles, we demonstrate that the specific adsorption model enables a rational explanation of the reaction difference of cations with different solvation structures at the electrode/electrolyte interfaces (EEIs). Specifically, owing to the more intense adsorption of active solvated Mn²⁺ near the inner Helmholtz plane, the deposition reaction of Mn species is enhanced in a sulfate-based electrolyte, resulting in a stronger capacity increase and fluctuation in comparison with sulfonate electrolytes. Similarly, the more rapid Zn²⁺ deposition kinetics in the sulfate-based electrolyte can be attributed to its strong adsorption behavior at the EEI. Furthermore, as validation of the as-proposed model, a sulfate/sulfonate hybrid electrolyte system is proposed, in which the optimized adsorption behavior at the EEI gives it synergistic improvement both in terms of capacity and cycling stability for aqueous Zn–Mn cells. This work provides rationale for understanding the interfacial electrochemistry in various aqueous electrolyte systems from the view of the adsorption behavior of the solvation structure.

Core–shell structured NiMoO₄@NiS₂/MoS₂ nanowires are fabricated via a novel facile in situ sulfurization method and applied in a high performance asymmetric supercapacitor.

The bifunctional NiFe LDH@Ni₃N/NF electrode exhibits superior electrocatalytic stability for overall water splitting at extremely high current densities.

An effective strategy of coating transition-metal nitrides with carbon to fabricate a Ni_xFe_yN@C/NF electrode for alkaline seawater electrolysis at extremely high current densities.