Dynamic stable interface between CNT and nanosilicon for robust anode with large capacity and high rate performance

The huge volume change and unstable interface of the silicon anode usually result in the fracture of the active material and the disconnection with conducting agent/current collector, which would highly hinder the application of silicon in powering battery. Moreover, the un-uniform charge distribution at the surfaces of silicon would cause a degration of capacity at fast charging condition or low temperature. Thus, developing a stable interface with good mechanical stability to tolerate huge volume change of the silicon, and keep the robust adhesive property is one of the effective methods of resolving the above questions but a great challenge. Here, a molecular zipper fastened strategy is designed to provide a dynamic stable interface for fast transportation of both ions and electrons, which can also provide a destroy-rebuilt interface for silicon. Through crosslinking of the binary polymer (PEDOT:PSS-PETU) and lithiated nafion (Li-nafion), the dynamic stable interface was constructed between nano-silicon and carbon nanotubes, leading to long cycling stability at room/freezing temperature (1850 mAh g−1 after 500 cycles at 1.0 A g−1 and 25°C,1917 mAh g−1 after 300 cycles at 1.0 A g−1 and 0°C), as well as high-rate performance (1328 mAh g−1 at 8.0 A g−1 and 25°C, 750 mAh g−1 at 4.0 A g−1 and 0°C). Finite element simulation results also confirm that the uniform electric distributed interface was constructed. The line contact model could minimize the stress caused by deformation during the fast lithiation/delithiation process. This approach offers an effective strategy for the next-generation high capacity, high rate, long lifespan and wide climate range ion battery.