Doped Carbon Xerogels for Lithium/Sodium-ion Battery Anodes

Silicon as an alloying-type anode material for Li/Na-ion batteries is a promising material due to the high specific capacity (~4200 mAh/g for Li+) and relative abundance in nature. However, it has been thoroughly observed that silicon during cycling due to the large volumetric difference (~400%) between its charged and discharged states. This instability causes unstable SEI formation and pulverization of the silicon, which leads to a premature failure of the anode. Therefore, a carbon xerogel (CX) support structure was synthesized via a sol-gel process, which provides a support structure and electronic/ionic conductivity for silicon nanoparticles (SiNPs) due to the unique 3D mesoporous network. Additionally, syntheses have been made using a protective ionomer, poly(sodium 4- styrenesulfonate) (PSS), as a binder. This unique polymer is able to infiltrate the CX/SiNPs composite and further protect the composite material from degradation due to its mechanical flexibility, high ionic conductivity, and good wetting properties