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

Abstract

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