Lawrence Berkeley National Laboratory

Pure Sn nanoparticles electrode with Poly(9,9-dioctylfluorene-co- fluorenone-co-methylbenzoic ester) (PFM) conductive binder was prepared and tested in sodium ion battery. It showed higher specific capacity and higher cycling stability without any carbon black compared with Sn/CMC (carboxy methylated cellulose) and Sn/PVDF (polyvinylidene fluoride) electrode. The Sn in Sn/PFM electrodes delivered 806 mAh g-1 at C/50 and 610 mAh g-1 at C/10. After 10 cycles at C/10, the capacity of Sn had no decay. SEM and TEM images showed that the Sn particles in Sn/PFM electrode were still in good conductive network despite big volume change, but parts of Sn particles in Sn/CMC or Sn/PVDF electrode are electrically isolated.