Rationally Designed Solution-Processible Conductive Carbon Additive Coating for Sulfide-based All-Solid-State Batteries.

Sulfide-based all-solid-state batteries (ASSBs) have emerged as promising candidates for next-generation energy storage systems owing to their superior safety and energy density. A conductive agent is necessarily added in the cathode composite of ASSBs to facilitate electron transport therein, but it causes the decomposition of the solid electrolyte and ultimately the shortening of lifetime. To resolve this dilemmatic situation, herein, we report a rationally designed solution-processible coating of zinc oxide (ZnO) onto vapor-grown carbon fiber as a conductive agent to reduce the contact between the carbon additive and the solid electrolyte and still maintain electron pathways to the active material. ASSBs with the carbon additive with an optimal coating of ZnO have markedly improved cycling performance and rate capability compared to those with the bare conductive agent, which can be attributed to hindering the decomposition of the solid electrolytes. The results highlight the usefulness of controlling the interparticle contacts in the composite cathodes in addressing the challenging interfacial degradation of sulfide-based ASSBs and improving their key electrochemical properties.

Improved Redox Reaction of Lithium Polysulfides on the Interfacial Boundary of Polar CoC2 O4 as a Polysulfide Catenator for a High-Capacity Lithium-Sulfur Battery.

Invited for this month's cover is the group of Jaeyoung Lee at the Gwangju Institute of Science and Technology. The cover shows how the cobalt oxalates faced on the conductive carbon can act as an electrocatalyst to facilitate the redox reaction of lithium polysulfide at the cathode interface in lithium-sulfur batteries. The facilitated electrochemical redox reaction of lithium polysulfides was proved by a series of catenation reactions formed on the interfacial boundary area. The electrochemical performance was enhanced in terms of the specific capacity and long-term cycle performance from the facilitated electrochemical activity. The Full Paper itself is available at 10.1002/cssc.202002140.

Improved Redox Reaction of Lithium Polysulfides on the Interfacial Boundary of Polar CoC2 O4 as a Polysulfide Catenator for a High-Capacity Lithium-Sulfur Battery.

The performance of cobalt oxalate as an electrocatalyst in a lithium-sulfur battery (LSB) is improved owing to the suitable adsorbent properties of sulfur. The adsorption mechanism is elucidated by UV/Vis spectroscopy and surface analysis through X-ray photoelectron spectroscopy. Li2 S6 is converted into thiosulfate and polythionate by a catenation reaction on the interfacial boundary of CoC2 O4 contacted with carbon. Following this, the active polythionate and short-chained liquid lithium polysulfides (LiPS) bound to the cobalt surface are further reduced as CoC2 O4 reduces the overpotential to facilitate the LiPS redox reaction, leading to high specific capacity, lower self-discharge rate, and stable long-term cycling performance.