Chemical induced delithiation on LixMnPO4: an investigation about the phase structure

TL;DR

This study investigates the phase structure changes in LixMnPO4 during chemical delithiation, comparing bare and carbon-coated samples, and analyzing their atomic and electronic structures to improve understanding of their electrochemical behavior.

Contribution

It provides a detailed comparison of phase structures and local atomic/electronic structures of chemically delithiated LixMnPO4, including effects of carbon coating and deviations in delithiation levels.

Findings

Deviations in delithiation degrees revealed by cerimetric analysis.

Structural characterization confirms phase changes consistent with literature.

Carbon coating influences delithiation behavior and phase stability.

Abstract

Understanding the LiMnPO4/MnPO4 phase transition is of great interest in order to further improve the electrochemical performance of this cathode material. Since most of the previously published literature deals with characterization of chemically delithiated Lix MnPO4, the aim of this study is to compare and study the composition and structure of the different phases that are generated upon chemical delithiation of LixMnPO4. Bare and carboncoated lithium manganese phos-phates are prepared via a combined coprecipitation-calcination method. Partial delithiation to two different degrees of delithiation Lix MnPO4 (x = 0.24/0.23 and 0.45) for carbon-coated and/or bare materials is achieved using an excess of nitro-nium tetrafluoroborate in acetonitrile. The effect of carboncoating has been also considered. Standard materials characterization with XRD (X-Ray Diffraction) and ICPOES (Inductive Coupled Plasma spectrometry and Optical Emission Spectroscopy) analysis are in accordance with literature data, but further cerimetric analysis revealed serious deviations, showing differences in the degree of delithiation to the average degree of oxidation. A structural characterization of the atomic and electronic local structure of the materials is also ob-tained using XAS (X-ray Absorption Spectroscopy) technique.