In Situ Construction of Crumpled Ti3C2Tx Nanosheets Confined S-Doping Red Phosphorus by Ti-O-P Bonds for LIBs Anode with Enhanced Electrochemical Performance.

Abstract

Red phosphorus (RP) with a high theoretical specific capacity (2596 mA h g^-1) and a moderate lithiation potential (∼0.7 V vs Li⁺/Li) holds promise as an anode material for lithium-ion batteries (LIBs), which still confronts discernible challenges, including low electrical conductivity, substantial volumetric expansion of 300%, and the shuttle effect induced by soluble lithium polyphosphide (Li_xPP_s). Here, S-NRP@Ti₃C₂T_x composites were in situ prepared through a phosphorus-amine-based method, wherein S-doped red phosphorus nanoparticles (S-NRP) grew and anchored on the crumpled Ti₃C₂T_x nanosheets via Ti-O-P bonds, constructing a three-dimensional porous structure which provides fast channels for ion and electron transport and effectively buffers the volume expansion of RP. Interestingly, based on the results of adsorption experiments of polyphosphate and DFT calculation, Ti₃C₂T_x with abundant oxygen functional groups delivers a strong chemical adsorption effect on Li_xPP_s, thus suppressing the shuttle effect and reducing irreversible capacity loss. Furthermore, S-doping improved the conductivity of red phosphorus nanoparticles, facilitating Li-P redox kinetics. Hence, the S-NRP@Ti₃C₂T_x anode demonstrates outstanding rate performance (1824 and 1090 mA h g^-1 at 0.2 and 4.0 A g^-1, respectively) and superior cycling performance (1401 mAh g^-1 after 500 cycles at 2.0 A g^-1).