Conductive Polymer Binder-Enabled Cycling of Pure Tin Nanoparticle Composite Anode Electrodes for a Lithium-Ion Battery

Pure tin (Sn) nanoparticles can be cycled in stable and high gravimetric capacity (>500 mAh/g) with a polyfluorene-type conductive polymer binder in composite electrodes. Crystalline Sn nanoparticles (<150 nanometers, nm) were used as anode materials in this study. The average diameter of Sn secondary particles is 270 nm, calculated based on BET surface area. The composite electrodes contain a conductive polymer binder that constitutes 2% to 10% of the material, without any conductive additives (e.g., acetylene black). The electrode containing the 5% conductive binder showed the best cycling performance, with a reversible capacity of 510 mAh/g. Crystallinity of Sn particles gradually degrades during cycling, and pulverization of particles was observed after long-term cycling, leading to the capacity fade. The conductive polymer binder shows advantages over other conventional binders, such as Poly(vinylidene difluoride) (PVDF) and carboxymethylcellulose (CMC) binders, because it can provide electrical conductivity and strong adhesion during Sn volume change.