Issue 7, 2024

Ammonia-free synthesis of lithium manganese iron phosphate cathodes via a co-precipitation reaction

Abstract

LiMnxFe1−xPO4 (LMFP) has emerged as a promising cathode material for Li-ion batteries due to its lower cost, better sustainability, and improved thermal and cycling stabilities compared to layered oxide cathodes. The incorporation of Mn in LMFP increases the operating voltage, and therefore the theoretical energy density, compared to LiFePO4. However, with high Mn content, it is difficult to fully utilize the Mn2+/3+ redox due to sluggish kinetics, resulting in a lower practical capacity. Atomic-scale mixing of Mn and Fe is crucial for the optimal electrochemical performance of LMFP, yet the practical scalability and the ease of synthesizing precursor compositions with different Mn contents through co-precipitation reaction remains underexplored. We present here for LMFP manufacturing a novel, scalable precursor (Mn, Fe)5(PO4)2(HPO4)2·4H2O, which is air-stable and is synthesized without the use of ammonia, for the first time. The role of the reactants, pH, and temperature in controlling the phase purity and morphology of the precursor are explored. Particularly, it is found that phase purity is highly sensitive to the Mn : Fe ratio and temperature during co-precipitation. The LMFP cathodes synthesized with the precursor exhibit excellent cycling stability, retaining over 95% capacity after 150 cycles at a C/3 rate. However, while higher Mn content (>60%) increases the average voltage, the specific capacity decreases due to sluggish kinetics, limiting the benefit to energy density. This work presents an industrially scalable method to synthesize mixed precursors for LMFP cathodes with a wide range of Mn contents providing a pathway to fine-tune the Mn content and particle morphology for optimal electrochemical performance.

Graphical abstract: Ammonia-free synthesis of lithium manganese iron phosphate cathodes via a co-precipitation reaction

Supplementary files

Article information

Article type
Paper
Submitted
14 3 2024
Accepted
08 6 2024
First published
13 6 2024
This article is Open Access
Creative Commons BY-NC license

RSC Sustain., 2024,2, 1969-1978

Ammonia-free synthesis of lithium manganese iron phosphate cathodes via a co-precipitation reaction

P. Vanaphuti, K. Scanlan and A. Manthiram, RSC Sustain., 2024, 2, 1969 DOI: 10.1039/D4SU00125G

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements