Use of Hydrothermal Carbonization to Improve the Performance of Biowaste-Derived Hard Carbons in Sodium Ion-Batteries.

Over the last years, hard carbon (HC) has been the most promising anode material for sodium-ion batteries due to its low voltage plateau, low cost and sustainability. In this study, biomass waste (spent coffee grounds, sunflower seed shells and rose stems) was investigated as potential material for hard carbon preparation combining a two-step method consisting of on hydrothermal carbonization (HTC), to remove the inorganic impurities and increase the carbon content, and a subsequent pyrolysis process. The use of HTC as pretreatment prior to pyrolysis improves the specific capacity in all the materials compared to the ones directly pyrolyzed by more than 100 % at high C-rates.

Mechanistic implications of Li-S cell function through modification of organo-sulfur cathode architectures.

Copolymeric organo-sulfur based electrodes provide a unique framework to explore and subsequently improve lithium-sulfur (Li-S) cells. There is a general difference in the way copolymers trap lithium during cell function compared to inorganic carbon-sulfur composites. Using a chain-like polyterpene copolymeric architecture involving the copolymerization of squalene monomer with sulfur (poly(S-r-squalene)), the first evidence for distinguishable differences in the entrapment of lithiated species, when using different copolymeric architectures, is provided.

Elucidation of structures and lithium environments for an organo-sulfur cathode.

Composite organo-sulfur cathodes provide a unique platform for the realization of lithium-sulfur (Li-S) cells. However, difficulties arise in the interpretation of the function of these electrodes in Li-S cells and the role they play in suppressing the so-called 'shuttle effect'. This work focuses on monitoring in detail the structural evolution and lithium environments during charge-discharge cycles in a lithium half-cell of an organo-sulfur cathode, which was synthesised by inverse vulcanisation with 1,3-diisopropenylbenzene.