Sacrificial Catalyst of Carbothermal-Shock-Synthesized 1T-MoS2 Layers for Ultralong-Lifespan Seawater Battery

A Pt-nanoparticle-decorated 1T-MoS2 layer is designed as a sacrificial electrocatalyst by carbothermal shock (CTS) treatment to improve the energy efficiency and lifespan of seawater batteries. The phase transition of MoS2 crystals from 2H to metallic 1T???induced by the simple but potent CTS treatment???improves the oxygen-reduction-reaction (ORR) activity in seawater catholyte. In particular, the MoS2-based sacrificial catalyst effectively decreases the overpotential during charging via edge oxidation of MoS2, enhancing the cycling stability of the seawater battery. Furthermore, Pt nanoparticles are deposited onto CTS-MoS2 via an additional CTS treatment. The resulting specimen exhibits a significantly low charge/discharge potential gap of ??0.39 V, high power density of 6.56 mW cm???2, and remarkable cycling stability up to ???200 cycles (???800 h). Thus, the novel strategy reported herein for the preparation of Pt-decorated 1T-MoS2 by CTS treatment could facilitate the development of efficient bifunctional electrocatalysts for fabricating seawater batteries with long service life

Unveiling the electrochemical characteristics of acetonitrile-catholyte-based Na-CO2 battery

The development of metal-CO2 batteries has attracted intense attention because of their unique electrochemical reaction for utilization of CO2 gas. However, unlike the alkali metal-based O2 batteries, a limited number of combinations of aprotic electrolytes have been employed for Li(Na)???CO2 batteries due to the sluggish reaction for the formation of the Li(Na)2CO3 discharge product. Here, we demonstrate an acetonitrile (MeCN)-based catholyte for use in a hybrid cell type Na-CO2 battery. The presence of a solid ceramic separator in our hybrid cell allows the stable operation of the MeCN catholyte-based Na-CO2 battery, resulting in improved electrochemical characteristics such as low overpotential, high energy density, and long cycle stability compared to the conventional TEGDME-based electrolyte. In particular, results of molecular dynamics simulations suggest that the improved performance is mainly due to the enhanced Na+ diffusion in the electrolyte. The calculated barrier for Na+ diffusion in MeCN is approximately four times lower than that in TEGDME. Thus, this work provides a promising electrolyte combination and reveals the mechanism for the improved performance of the MeCN-based electrolyte used in the hybrid cell structure, promoting the development of Na-CO2 batteries as practical secondary energy storage devic