Multi‐Component Phase Engineering Strategy Modulates Potassiation Reaction Energy Barrier of Alloying Anode for Stable Potassium Storage

Abstract Red phosphorus (RP) has received much attention in potassium storage because of its inexpensive cost and high theoretical capacity, but faces the issues of volume expansion and poor conductivity. Fortunately, phosphorus–selenium hybridization solves these issues by forming an alloy anode that combines RP's high capacity with Se's high conductivity. But the weak chemical affinity between RP and Se makes it often difficult to form stable and homogeneous mixtures during preparation. To address this, this study introduces hexagonal boron nitride (h‐BN) as a bridging source to facilitate the close coupling of the RP and Se composite phases. The optimized multi‐component anode exhibits high initial coulombic efficiency (ICE reaching 73.0%), good cycling stability (3000 cycles at 1 A g ⁻¹ ), and outstanding rate performance (a discharge specific capacity of 157.3 mAh g⁻¹ even at 2 A g⁻¹). Further investigation reveals that the introduction of h‐BN reduces activation energy for interfacial charge transfer and K ⁺ to cross the solid electrolyte interphase (SEI). It also decreases the Gibbs free energy change (ΔG) of the potassiation reaction's decisive step. Therefore, the introduction of a third phase enhances the coupling effect of alloy‐based composites, providing a method for designing secondary battery electrodes with high capacity.