Microporous bamboo biochar for lithium-sulfur batteries

Abstract

Being simple, inexpensive, scalable and environmentally friendly, microporous biomass biochars have been attracting enthusiastic attention for application in lithium-sulfur (Li-S) batteries. Herein, porous bamboo biochar is activated via a KOH/annealing process that creates a microporous structure, boosts surface area and enhances electronic conductivity. The treated sample is used to encapsulate sulfur to prepare a microporous bamboo carbon-sulfur (BC-S) nanocomposite for use as the cathode for Li-S batteries for the first time. The BC-S nanocomposite with 50 wt.% sulfur content delivers a high initial capacity of 1,295 mA·h/g at a low discharge rate of 160 mA/g and high capacity retention of 550 mA·h/g after 150 cycles at a high discharge rate of 800 mA/g with excellent coulombic efficiency (≥95%). This suggests that the BC-S nanocomposite could be a promising cathode material for Li-S batteries.

Biomass-derived renewable carbon materials for electrochemical energy storage

“…For lithium-sulfur battery applications, these C/S composites are able to manipulate 'shuttle effects' for better stability, while larger pores to facilitate ion transportation for improving rate performance. To date, all kinds of biomass precursors, such as pig bone [142], fish scales [66], shrimp shell [143], litchi shells [144], olive stones [145], cotton [146], silk cocoon [147], bamboo [148], wheat straw [149], mango stone [150], pomelo peels [151], banana peels [152], gelatin [153], cassava [154], bark of plane trees [155], starch [156], have been widely explored to prepare hierarchical porous carbons by well-deigned carbonization processes. All of these biomass-derived hierarchical carbons can be used as conductive host of sulfur for lithium-sulfur battery with improved electrochemical performances.…”

Recent development of metal compound applications in lithium–sulphur batteries

“…8 121 incorporated a fine amount of ZrO 2 to the holey CNT-sulphur composites. The holey CNT contributed to the good conductivity of the h-CNT/S/ZrO 2 cathode, while appropriate ZrO 2 loading preserved the permselective channels for Li 1 intercalation/deintercalation and trapped the soluble polysulphides.…”

“…First of all, the low electric and Li 1 -ionic conductivity of elemental sulfur and discharged end-product (Li 2 S and Li 2 S 2 ), which will result in low utilization of active materials and poor coulombic efficiency. 7,8 Secondly and most importantly, the discharged intermediatespolysulphides easily dissolve in the organic electrolyte. 8 These polysulfide anions (S x 2À ) can diffuse to the anode, causing tremendous loss of active materials, extremely low coulombic efficiency, and rapid capacity fading.…”

“…7,8 Secondly and most importantly, the discharged intermediatespolysulphides easily dissolve in the organic electrolyte. 8 These polysulfide anions (S x 2À ) can diffuse to the anode, causing tremendous loss of active materials, extremely low coulombic efficiency, and rapid capacity fading.…”

“…Important progress was made by Nazar and coworkers, 15 who showed that by fabricating cathodes where sulfur had been encapsulated into nanostructured mesoporous carbon, high reversible capacities and good rates can be obtained due to the enhanced conductivity and physical confinement of the polysulphides via the mesopores. Since then, various nanostructured conductive carbon, such as carbon fibers, 16 graphene, 17 carbon nanotubes (CNT), 13 carbon spheres, 18 porous carbon, 8 etc., have been used to improve the sulfur utilization and extend the sulfur cathode cycling performances. However, the conjugate nonpolar carbon planes have limited sites to strongly anchor polar molecules (e.g., lithium polysulphides and (di)sulphides).…”