VN/S Nanoclusters Encapsulated with Graphene via Zeta Potential Control: A Pomegranate‐Like Cathode for Lithium‐Sulfur Batteries with Enhanced Rate Performance

Graphdiyne-like Porous Organic Framework as a Solid-Phase Sulfur Conversion Cathodic Host for Stable Li-S Batteries

As a unique branch of Li-S batteries, solid-phase sulfur conversion polymer cathodes have shown superior stability with fast ion-transfer kinetics and high discharge capacities owing to the mere existence of short-chain sulfur species during charging/discharging. However, representative compounds such as sulfurized polyacrylonitrile (SPAN) and polyaniline (SPANI) suffer from low sulfur contents and poor cycling performances under large current densities due to the sulfurization occurring only on polymers' surface. Here, a graphdiyne-like porous organic framework, denoted as GPOF, is synthesized and used as a host for enabling solid-phase sulfur conversion. Plenty of unsaturated bonds in GPOF provide sufficient reaction sites to bind sulfur chains, resulting in a high active sulfur content in the cathode. Moreover, the microporous GPOF possesses suitable cavities to accommodate the volume expansion, leading to favorable long-term cycling stability. As a result, the sulfurized GPOF cathode (SGPOF-320) displays outstanding electrochemical stability with negligible capacity decline after 250 cycles at 0.2 C with an average discharge capacity of 925 mA h g^-1. Our work applies a facile procedure to produce sulfur conversion porous polymer cathodes, which could provide a proper way for exploring more suitable cathode materials for high-performance Li-S batteries.

Progress and innovation of nanostructured sulfur cathodes and metal-free anodes for room-temperature Na-S batteries

Rechargeable batteries are a major element in the transition to renewable energie systems, but the current lithium-ion battery technology may face limitations in the future concerning the availability of raw materials and socio-economic insecurities. Sodium-sulfur (Na-S) batteries are a promising alternative energy storage device for small- to large-scale applications driven by more favorable environmental and economic perspectives. However, scientific and technological problems are still hindering a commercial breakthrough of these batteries. This review discusses strategies to remedy some of the current drawbacks such as the polysulfide shuttle effect, catastrophic volume expansion, Na dendrite growth, and slow reaction kinetics by nanostructuring both the sulfur cathode and the Na anode. Moreover, a survey of recent patents on room temperature (RT) Na-S batteries revealed that nanostructured sulfur and sodium electrodes are still in the minority, which suggests that much investigation and innovation is needed until RT Na-S batteries can be commercialized.