Rational design of porous carbon matrices to enable efficient lithiated silicon sulfur full cell

Abstract

Lithium sulfur technology is a promising near-future battery owing to its high theoretical capacity and low cost materials; nonetheless, its commercial viability is hindered owing to the use of lithium anode. Reactive Li is prone to dendritic growth, causing short-circuits and aggravating electrolyte depletion. Here, lithiated silicon sulfur (SLS) full cells are realized by opting all-designs integrated strategy to rationally architecture the carbon matrices for both electrodes. For cathode, N/S- doped high surface area hierarchical porous carbons are designed to host sulfur and its redox species. Anodes are constructed by electrospinning using nano-silicon@void@carbon nanofibers (SVCNF) cross-linked with alginate-citric acid binder network. As-prepared anodes are reversibly alloyed and dealloyed with high reversible capacity of 2132 mAh gSi−1 (427 mAh gSi/CNF−1) after 150 cycles at 716 mA gSi−1 in ether-based electrolyte. At cathode, polypyrrole activated hierarchical carbon sulfur (PPyr_C/S) exhibits very stable performance with capacity retention around 767 mAh gS−1 after 250 at C/5. After balancing with low Li excess, lithiated SVCNF anodes are coupled with PPyr_C/S cathodes, with initial capacity of 972 mAh gS−1 and 50% capacity retention after 100 cycles at 225 mA gS−1. Full SLS cells have been appreciated by opting rational architecture of carbon matrices in individual electrodes even at low lithium excess.