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

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 PP 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. The introduction of I2 can simultaneously catalyze the acceleration of white phosphorus polymerization and enhance red phosphorus potassiation for high-performance potassium-ion batteries. The P/C composites with an I2 catalyst deliver excellent cycling stability (358 mAh g-1 after 1200 cycles at 1 A g-1) and excellent rate performance (200 mAh g-1 at 10 A g-1).image

Automated summary

By using I2 as a catalyst, the polymerization process of white phosphorus can be accelerated and the alloying reaction of red phosphorus can be enhanced, leading to improved cycling stability and rate performance of potassium-ion batteries.