Driven by the urgent requirements for sustainable lithium-ion batteries, the re-utilization of spent graphite featuring accumulated defects and interfacial degradation is shifting from simple compositional recovery toward functional reconfiguration. Herein, an effective interfacial strategy is proposed to upcycle spent graphite into recycled graphite encapsulated by amorphous Al₂O₃ nanonetworks (denoted as ARG) via a facile low-temperature heat treatment. According to experimental and theoretical calculation results, the amorphous Al₂O₃ coating containing Lewis-acidic Al³⁺ sites can strongly interact with electrolytic solvent molecules to reduce the Li⁺ desolvation energy barrier, catalyzing the formation of a LiF-rich SEI layer with improved electronic conductivity and reduced interfacial charge transfer resistance. Moreover, thin Al₂O₃ interphase, featuring negative Li⁺ adsorption energy, couples effectively with inherent bulk defects, thereby enabling substantially enhanced Li⁺ trapping and storage via multidimensional ion diffusion pathways. Contributing to the interfacial “catalytic-percolative” regulation, ARG anode exhibits an ultra-high capacity (394 mAh g^–1), superior rate performance and excellent cycling stability even at 4 C, providing novel insights into constructing fast-charging and durable upcycled graphite with significant economic and ecological value.

Layered Mn-based oxides are one of the promising cathode materials for potassium-ion batteries (KIBs) owing to their high theoretical capacities, abundant material supply, and simple synthesis method. However, the structural deterioration resulting from the Jahn-Teller effect of Mn ions hinders their further development in KIBs. Herein, a novel Mn-based layered oxide, K_0.54Mn_0.78Mg_0.22O₂, is successfully designed and fabricated as KIBs cathode for the first time. It delivers smooth charging/discharging curves with high specific capacity of 132.4 mAh·g^‒1 at 20 mA·g^‒1 and good high-rate cycling stability with a capacity retention of 84% over 100 cycles at 200 mA·g^‒1. Combining in-situ X-ray diffraction (XRD) and ex-situ X-ray photoelectron spectroscopy (XPS) analysis, the storage of K-ions by K_0.54Mn_0.78Mg_0.22O₂ is revealed to be a solid-solution processes with reversible slip of the crystal lattice. The studies suggest that the rational doping of inactive Mg²⁺ can effectively suppress the Jahn-Teller effect and provide outstanding structure stability. This work deepens the understanding of the structural evolution of Mn-based layered materials doped with inactive materials during de/potassiation processes.