Potassium‐ion batteries (PIBs) have emerged as a compelling complement to existing lithium‐ion batteries for large‐scale energy storage applications, due to the resource‐abundance of potassium, the low standard redox potential and high conductivity of K+‐based electrolytes. Rapid progress has been made in identifying suitable carbon anode materials to address the sluggish kinetics and huge volume variation problems caused by large‐size K+. However, most research into carbon materials has focused on structural design and performance optimization of one or several parameters, rather than considering the holistic performance especially for realistic applications. This perspective examines recent efforts to enhance the carbon anode performance in terms of initial Coulombic efficiency, capacity, rate capability, and cycle life. The balancing of the intercalation and surface‐driven capacitive mechanisms while designing carbon structures is emphasized, after which the compatibility with electrolyte and the cell assembly technologies should be considered under practical conditions. It is anticipated that this work will engender further intensive research that can be better aligned toward practical implementation of carbon materials for K+ storage.
Constructing robust nucleation sites with an ultrafine size in a confined environment is essential toward simultaneously achieving superior utilization, high capacity, and long-term durability in Na metal-based energy storage, yet remains largely unexplored. Here, we report a previously unexplored design of spatially confined atomic Sn in hollow carbon spheres for homogeneous nucleation and dendrite-free growth. The designed architecture maximizes Sn utilization, prevents agglomeration, mitigates volume variation, and allows complete alloying-dealloying with high-affinity Sn as persistent nucleation sites, contrary to conventional spatially exposed large-size ones without dealloying. Thus, conformal deposition is achieved, rendering an exceptional capacity of 16 mAh cm
−2
in half-cells and long cycling over 7000 hours in symmetric cells. Moreover, the well-known paradox is surmounted, delivering record-high Na utilization (e.g., 85%) and large capacity (e.g., 8 mAh cm
−2
) while maintaining extraordinary durability over 5000 hours, representing an important breakthrough for stabilizing Na anode.
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