Interlayer and Phase Engineering Modifications of K-MoS₂@C Nanoflowers for High-Performance Degradable Zn-Ion...

2D transition metal dichalcogenides (TMDs) have garnered significant interest as cathode materials for aqueous zinc-ion batteries (AZIBs) due to their open transport channels and abundant Zn²⁺ intercalation sites. However, unmodified TMDs exhibit low electrochemical activity and poor kinetics owing to the high binding energy and large hydration radius of divalent Zn²⁺. To overcome these limitations, an interlayer engineering strategy is proposed where K⁺ is preintercalated into K-MoS₂ nanosheets, which then undergo in situ growth on carbon nanospheres (denoted as K-MoS₂@C nanoflowers). This strategy stimulates in-plane redox-active sites, expands the interlayer spacing (from 6.16 to 9.42 Å), and induces the formation of abundant MoS₂ 1T-phase. The K-MoS₂@C cathode demonstrates excellent redox activity and fast kinetics, attributed to the potassium ions acting as a structural "stabilizer" and an electrostatic interaction "shield," accelerating charge transfer, promoting Zn²⁺ diffusion, and ensuring structural stability. Meanwhile, the carbon nanospheres serve as a 3D conductive network for Zn²⁺ and enhance the cathode's hydrophilicity. More significantly, the outstanding electrochemical performance of K-MoS₂@C, along with its superior biocompatibility and degradability of its related components, can enable an implantable energy supply, providing novel opportunities for the application of transient electronics.