Phosphor-Doped Carbon Network Electrocatalyst Enables Accelerated Redox Kinetics of Polysulfides for Sodium-Sulfur Batteries.

Lithium-ion batteries, which have dominated large-scale energy storage for the past three decades, face limitations in energy density and cost. Sulfur, with its impressive capacity of 1675 mAh g-1 and high theoretical energy density of 1274 Wh kg-1, stands out as a promising cathode material, leading to a growing focus on sodium-sulfur (Na-S) batteries as an alternative to address lithium resource scarcity. Nevertheless, the development is restrained by poor conductivity, volume expansion of the sulfur cathode, and the shuttle effect of sodium polysulfides (Na2Sn) in the electrolytes. In this study, a facile method is designed to fabricate phosphor-doped carbon (phos-C), which is then used as a sulfur matrix. This micromesoporous phos-C network enhances sulfur utilization, increases overall cathode conductivity, and effectively mitigates the shuttling of Na2Sn. During the discharge process, phos-C can absorb soluble Na2Sn and increase the conductivity of sulfur, while serving as a reservoir for electrolyte and Na2Sn, thereby preventing their infiltration into the anode and reducing the loss of sodium. As a result, the well-designed sulfur-loaded phos-C (S/phos-C) cathode, employed in the Na-S battery, demonstrates a capacity of 1034 mAh g-1 at 0.1 C (1 C = 1675 mA g-1) and an excellent rate capability of 339 mAh g-1 at 10 C, coupled with a prolonged cycling life up to 2000 cycles at 1 C, exhibiting an ultralow capacity decay rate of 0.013% per cycle. Overall, this study introduces an efficient method for creating long-lasting Na-S batteries.

Quasi-waffle solar distiller for durable desalination of seawater.

Water purification via interfacial solar steam generation exhibits promising potential. However, salt crystallization on evaporators reduces solar absorption and obstructs water supply. To address it, a waffle-shaped solar evaporator (WSE) has been designed. WSE is fabricated via a zinc-assisted pyrolysis route, combining low-cost biomass carbon sources, recyclable zinc, and die-stamping process. This route enables cost-effective production without the need of sophisticated processing. As compared to conventional plane-shaped evaporators, WSE is featured by extra sidewalls for triggering the convection with the synergistic solute and thermal Marangoni effects. Consequently, WSE achieves spontaneous salt rejection and durable evaporation stability. It has demonstrated continuous operation for more than 60 days in brine without fouling.