Elucidating the Dissolution of Lithium Phosphide Intermediates for Phosphorus Anodes in Ester‐Based Electrolyte

Phosphorus‐based anodes are gaining attention for high energy/power density lithium‐ion batteries (LIBs) due to their high theoretical capacity and moderate operating potential. Recent studies indicated the possible dissolution of lithium phosphide intermediates (LiPIs) in organic solvents, raising concerns about whether phosphorus anodes in LIB systems might face similar dissolution issues as sulfur cathodes in lithium‐sulfur batteries. We investigated the dissolution property of LiPIs in ester electrolytes with different lithium salts, using semi‐quantitative liquid nuclear magnetic resonance for analysis. Our results indicate that no polyphosphide anions such as P 5 − , P 7 3− , P 16 2− , and P 21 3− were detected in the cycled ethylene carbonate (EC)‐based electrolyte, only F 2 PO 2 Li and OPF 2 (OC 2 H 5 ) were present. Further X‐ray photoelectron spectroscopy shows no phosphorus element detected on the counter electrode when using EC‐based electrolyte. These suggest that the LiPIs have very low solubility in EC‐based electrolytes, below 0.1 mM, thus preventing shuttle effects similar to those in lithium‐sulfur batteries. Our study addresses concerns from academia and industry about LiPIs dissolution, confirming the stability and safety of phosphorus‐based anodes for high‐performance LIBs.