Root-Growth-Inspired Self-Morphology-Evolution of Microsized Bismuth Surrounded by Microsized Hard Carbon for Stabilized Sodium-Ion Storage.

Alloy-type materials are desirable for high-energy sodium-ion batteries. Different from nanoengineering with pre-reserving void space and confined carbon coatings, microsized particles promise high specific/volumetric capacities, easy manufacturing, and low cost but are prone to rapid capacity loss. Herein, inspired by the process of "root growth in soil", microsized Bi particles (µm-Bi, as "seeds") surrounded by microsized hard carbon particles (µm-HC, as "soil") are ingeniously dispersed through a simple mixing approach.

Interlayer Confined Water Enabled Pseudocapacitive Sodium-Ion Storage in Nonaqueous Electrolyte.

Electrochemical capacitors have faced the limitations of low energy density for decades, owing to the low capacity of electric double-layer capacitance (EDLC)-type positive electrodes. In this work, we reveal the functions of interlayer confined water in iron vanadate (FeVO·HO) for sodium-ion storage in nonaqueous electrolyte. Using an electrochemical quartz crystal microbalance, Raman, and X-ray diffraction and X-ray photoelectron spectroscopy, we demonstrate that both nonfaradaic (surficial EDLC) and faradaic (pseudocapacitance-dominated Na intercalation) processes are involved in the charge storages.