Aging and Charge Compensation Effects of the Rechargeable Aqueous Zinc/Copper Hexacyanoferrate Battery Elucidated Using In Situ X-ray Techniques.

The zinc/copper hexacyanoferrate (Zn/CuHCF) cell has gained attention as an aqueous rechargeable zinc-ion battery (ZIB) owing to its open framework, excellent rate capability, and high safety. However, both the Zn anode and the CuHCF cathode show unavoidable signs of aging during cycling, though the underlying mechanisms have remained somewhat ambiguous. Here, we present an in-depth study of the CuHCF cathode by employing various X-ray spectroscopic techniques.

Nanostructured diatom earth SiO negative electrodes with superior electrochemical performance for lithium ion batteries.

Diatomaceous earth (DE) is a naturally occurring silica source constituted by fossilized remains of diatoms, a type of hard-shelled algae, which exhibits a complex hierarchically nanostructured porous silica network. In this work, we analyze the positive effects of reducing DE SiO particles to the sub-micrometer level and implementing an optimized carbon coating treatment to obtain DE SiO anodes with superior electrochemical performance for Li-ion batteries. Pristine DE with an average particle size of 17 μm is able to deliver a specific capacity of 575 mA h g after 100 cycles at a constant current of 100 mA g, and reducing the particle size to 470 nm enhanced the reversible specific capacity to 740 mA h g.

Structure Characterization and Properties of K-Containing Copper Hexacyanoferrate.

Copper hexacyanoferrate, Cu(II)[Fe(III)(CN)6]2/3·nH2O, was synthesized, and varied amounts of K(+) ions were inserted via reduction by K2S2O3 (aq). Ideally, the reaction can be written as Cu(II)[Fe(III)(CN)6]2/3·nH2O + 2x/3K(+) + 2x/3e(-) ↔ K2x/3Cu(II)[Fe(II)xFe(III)1-x(CN)6]2/3·nH2O. Infrared, Raman, and Mössbauer spectroscopy studies show that Fe(III) is continuously reduced to Fe(II) with increasing x, accompanied by a decrease of the a-axis of the cubic Fm3̅m unit cell.