Additive Effects of LiBH₄ and ZrCoH₃ on the Hydrogen Sorption of the Li-Mg-N‑H Hydrogen Storage System

LiBH₄ is an effective catalyst for the hydrogen sorption of the Li-Mg-N-H storage system. A combination of LiBH₄ with ZrCoH₃ was reported to be catalytically more effective. In this work, materials doped with LiBH₄ or ZrCoH₃ or a combination of ZrCoH₃ and LiBH₄ were characterized both in the as-prepared and in the cycled states. A comparison of the metathesis conversion, thermal behavior, kinetics, and phase evolution induced by H₂ cycling suggests that the two components function additively. While LiBH₄ facilitates the metathesis conversion in the first cycle and enhances kinetics during H₂ cycling by forming a quaternary complex hydride, ZrCoH₃ has at least a pulverizing effect in the material. The chemical environment and near order of the individual atoms of Zr and Co as well as the structural parameters of ZrCoH₃ were investigated by X-ray absorption and found to be unchanged during H₂ cycling

Mechanical Milling Assisted Synthesis and Electrochemical Performance of High Capacity LiFeBO₃ for Lithium Batteries

Borate chemistry offers attractive features for iron based polyanionic compounds. For battery applications, lithium iron borate has been proposed as cathode material because it has the lightest polyanionic framework that offers a high theoretical capacity. Moreover, it shows promising characteristics with an element combination that is favorable in terms of sustainability, toxicity, and costs. However, the system is also associated with a challenging chemistry, which is the major reason for the slow progress in its further development as a battery material. The two major challenges in the synthesis of LiFeBO₃ are in obtaining phase purity and high electrochemical activity. Herein, we report a facile and scalable synthesis strategy for highly pure and electrochemically active LiFeBO₃ by circumventing stability issues related to Fe²⁺ oxidation state by the right choice of the precursor and experimental conditions. Additionally, we carried out a Mössbauer spectroscopic study of electrochemical charged and charged–discharged LiFeBO₃ and reported a lithium diffusion coefficient of 5.56 × 10^–14 cm² s^–1 for the first time