Towards Practical Application of Li-S Battery with High Sulfur Loading and Lean Electrolyte: Will Carbon-Based Hosts Win This Race?

Relay-Type Catalysis by a Dual-Metal Single-Atom System in a Waste Biomass Derivative Host for High-Rate and Durable Li-S Batteries

An environmental-friendly and sustainable carbon-based host is one of the most competitive strategies for achieving high loading and practicality of Li-S batteries. However, the polysulfide conversion reaction kinetics is still limited by the nonuniform or monofunctional catalyst configuration in the carbon host. In this work, we propose a catalysis mode based on "relay-type" co-operation by adjacent dual-metal single atoms for high-rate and durable Li-S batteries. A discarded sericin fabric-derived porous N-doped carbon with a stacked schistose structure is prepared as the high-loading sulfur (84 wt %) host by a facile ionothermal method, which further enables the uniform anchoring of Fe/Co dual-metal single atoms. This multifunctional host enables superior lithiophilic-sulfiphilic and electrocatalytic capabilities contributed by the "relay-type" single-atom modulation effects on different conversion stages of liquid polysulfides and solid Li2S2/Li2S, leading to the suppression of the "shuttle effect", alleviation of nucleation and decomposition barriers of Li2Sx, and acceleration of polysulfide conversion kinetics. The corresponding Li-S batteries exhibit a high specific capacity of 1399.0 mA h g-1, high-rate performance up to 10 C, and excellent cycling stability over 1000 cycles. They can also endure the high sulfur loading of 8.5 mg cm-2 and the lean electrolyte condition and yield an areal capacity as high as 8.6 mA h cm-2. This work evidentially demonstrates the potential of waste biomass reutilization coupled with the design of a single-atom system for practical Li-S batteries with high energy density.

Effective Bidirectional Mott-Schottky Catalysts Derived from Spent LiFePO4 Cathodes for Robust Lithium-Sulfur Batteries

It is deemed as a tough yet profound project to comprehensively cope with a range of detrimental problems of lithium-sulfur batteries (LSBs), mainly pertaining to the shuttle effect of lithium polysulfides (LiPSs) and sluggish sulfur conversion. Herein, a Co2 P-Fe2 P@N-doped carbon (Co2 P-Fe2 P@NC) Mott-Schottky catalyst is introduced to enable bidirectionally stimulated sulfur conversion. This catalyst is prepared by simple carbothermal reduction of spent LiFePO4 cathode and LiCoO2 . The experimental and theoretical calculation results indicate that thanks to unique surface/interface properties derived from the Mott-Schottky effect, full anchoring of LiPSs, mediated Li2 S nucleation/dissolution, and bidirectionally expedited "solid⇌liquid⇌solid" kinetics can be harvested. Consequently, the S/Co2 P-Fe2 P@NC manifests high reversible capacity (1569.9 mAh g-1 ), superb rate response (808.9 mAh g-1 at 3C), and stable cycling (a low decay rate of 0.06% within 600 cycles at 3C). Moreover, desirable capacity (5.35 mAh cm-2 ) and cycle stability are still available under high sulfur loadings (4-5 mg cm-2 ) and lean electrolyte (8 µL mg-1 ) conditions. Furthermore, the as-proposed universal synthetic route can be extended to the preparation of other catalysts such as Mn2 P-Fe2 P@NC from spent LiFePO4 and MnO2 . This work unlocks the potential of carbothermal reduction phosphating to synthesize bidirectional catalysts for robust LSBs.

A Review on Engineering Design for Enhancing Interfacial Contact in Solid-State Lithium-Sulfur Batteries

The utilization of solid-state electrolytes (SSEs) presents a promising solution to the issues of safety concern and shuttle effect in Li-S batteries, which has garnered significant interest recently. However, the high interfacial impedances existing between the SSEs and the electrodes (both lithium anodes and sulfur cathodes) hinder the charge transfer and intensify the uneven deposition of lithium, which ultimately result in insufficient capacity utilization and poor cycling stability. Hence, the reduction of interfacial resistance between SSEs and electrodes is of paramount importance in the pursuit of efficacious solid-state batteries. In this review, we focus on the experimental strategies employed to enhance the interfacial contact between SSEs and electrodes, and summarize recent progresses of their applications in solid-state Li-S batteries. Moreover, the challenges and perspectives of rational interfacial design in practical solid-state Li-S batteries are outlined as well. We expect that this review will provide new insights into the further technique development and practical applications of solid-state lithium batteries.