Simultaneous Catalytic Acceleration of White Phosphorus Polymerization and Red Phosphorus Potassiation for High-Performance Potassium-Ion Batteries.

Abstract

Red phosphorus (P) as an anode material of potassium-ion batteries possesses ultra-high theoretical specific capacity (1154 mAh g^-1 ). However, owing to residual white P during the preparation and sluggish kinetics of K-P alloying limit its practical application. Seeking an efficient catalyst to address the above problems is crucial for the secure preparation of red P anode with high performance. Herein, through the analysis of the activation energies in white P polymerization, it is revealed that the highest occupied molecular orbital energy of I₂ (-7.40 eV) is in proximity to P₄ (-7.25 eV), and the lowest unoccupied molecular orbital energy of I₂ molecule (-4.20 eV) is lower than that of other common non-metallic molecules (N₂ , S₈ , Se₈ , F₂ , Cl₂ , Br₂ ). The introduction of I₂ can thus promote the breaking of the P─P bond and accelerate the polymerization of white P molecules. Besides, the ab initio molecular dynamics simulations show that I₂ can enhance the kinetics of P-K alloying. The as-obtained red P/C composites with I₂ deliver excellent cycling stability (358 mAh g^-1 after 1200 cycles at 1 A g^-1 ). This study establishes catalysis as a promising pathway to tackle the challenges of P anode for alkali metal ion batteries.