Polar Molecule Intercalation to Weaken P2─S Bonding in MnPS3 Toward Ultrahigh‐Capacity Sodium Storage

Abstract

Layered transition metal trithiophosphates (TMPS3, TM = Mn, Fe, Co, etc.) with high theoretical capacity (>1 300 mAh g−1) are potential anode materials for sodium‐ion batteries (SIBs). However, the strong bonding between P2 dimers and S atoms in TMPS3 hinders the efficient alloying reaction between P2 dimers and Na+, resulting in practical capacities much lower than theoretical values. Herein, a polar molecule diisopropylamine (DIPA) is intercalated into MnPS3 for the first time to improve the sodium storage performance effectively. Theoretical calculations show that the electron transfer between DIPA and MnPS3 induces more delocalized S p states and weaker P─S bonds, significantly enhancing the electrochemical activity and sodiation/desodiation reaction kinetics. Moreover, the expanded interlayer spacing from 6.48 to 10.75 Å enables faster Na+ diffusion and more active sites for Na+ adsorption. As expected, the DIPA‐MnPS3 exhibits an ultrahigh capacity of 1,023 mAh g−1 at 0.2 A g−1 and excellent cycling performance (≈100% capacity retention after 4 200 cycles at 10 A g−1), far outperforming those metal thiophosphates anodes reported for SIBs. Interestingly, in situ and ex situ characterizations reveal a quasi‐topological intercalation mechanism of DIPA‐MnPS3. This work provides a novel strategy for the design of high‐performance anode materials for SIBs.