Unlocking the dissolution mechanism of phosphorus anode for lithium-ion batteries

Phosphorus is a promising anode material for fast-charging in lithium-ion batteries because of the combined advantages of high theoretical mass and volume specific capacity as well as a relatively low, yet safe lithiation potential to avoid Li metal dendrite formation. Previous studies have shown that the properties of phosphorus are similar to silicon. Both of their electrochemical performance are limited by the huge volumetric expansion during lithiation process and low electronic conductivity, however, there is still unknown exact mechanism of phosphorus. Here, we report that its lithium storage behavior is similar to that of sulfur because they are both molecular crystals, in which the fracture of P–P bonds generates the small molecules of polyphosphides, which can combine with the solvent via strong interaction, leading to the dissolution and shuttle effect, leading to a series of critical problems like active phosphorus loss and counter electrode corrosion. It is one of the main reasons for capacity decay. To address this issue, we introduced LiF as an additive, which provides the chemical adsorption of polyphosphides to suppress the shuttle effect, enabling an excellent long-term cycling stability with the capacity retention of 91.1% after 500 cycle.