Porous Silicon@Polythiophene Core–Shell Nanospheres for Lithium‐Ion Batteries

Abstract

Polythiophene‐coated porous silicon core–shell nanospheres (Si@PTh) composite are synthesized by a simple chemical oxidative polymerization approach. The polythiophene acts as a flexible layer to hold silicon grains when they are repeatedly alloying/dealloying with lithium during the discharge/charge process. The long lifespan and high‐current‐density rate ­capability (at a current of 8 A g −1 ) of the Si@PTh composite are vastly improved compared with as‐prepared Si spheres. Typically, these Si@PTh composite electrodes achieve a reversible capacity of 1130.5 mA h g −1 at 1 A g −1 current density after 500 cycles, and can even possess a discharge capacity up to 451.8 mA h g −1 at 8 A g −1 . The improved electrochemical performance can be ascribed to the synergy effects of the flexible PTh coating and the distinctive core–shell nanospheres with porous structure, which can largely alleviate the volume expansion of the Si during alloying with lithium.