Computational Investigation of Copper Phosphides as Conversion Anodes for Lithium-Ion Batteries
Angela F Harper1, Matthew L Evans1, Andrew J Morris2
1Theory of Condensed Matter, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, U.K.
Chemistry of Materials : a Publication of the American Chemical Society
|September 9, 2020
Summary
This study discovers a new copper phosphide (Cu-P) phase, Fm3m-Cu2P, and evaluates its potential as a high-capacity anode for lithium-ion batteries. The novel Cu2P phase shows promising stability and electrochemical performance for future battery applications.
Area of Science:
- Materials Science
- Computational Chemistry
- Electrochemistry
Background:
- Copper phosphides (Cu-P) are being explored as advanced anode materials for lithium-ion batteries.
- Understanding the structural stability and electrochemical properties of Cu-P phases is crucial for their practical application.
- Existing graphite anodes have limitations in terms of energy density and capacity.
Purpose of the Study:
- To identify novel copper phosphide structures using first-principles calculations.
- To determine the thermodynamic stability of these phases at finite temperatures.
- To assess the potential of predicted Cu-P phases as high-capacity anodes for lithium-ion batteries.
Main Methods:
- First-principles structure searching combined with density-functional theory (DFT) calculations.
- Calculation of Gibbs free energy, including vibrational effects from phonon modes, to construct a finite-temperature convex hull.
- Evaluation of theoretical gravimetric capacities and electrochemical properties for potential battery applications.
Main Results:
- Identification of a novel Fm3m phase of Cu2P and two metastable phases (I4̅3d-Cu3P and Cm-Cu3P11).
- Fm3m-Cu2P is found to be dynamically stable, and Cmc21-Cu8P3 remains metastable up to 600 K.
- Cu2P exhibits a high theoretical gravimetric capacity (508 mAh/g), exceeding that of Cu3P and graphite, and is predicted to be nonmagnetic and metallic.
Conclusions:
- The novel Fm3m-Cu2P phase is a promising candidate for a future conversion anode in lithium-ion batteries due to its high capacity and metallic properties.
- Cu2P anodes demonstrate potentially improved durability with a lower volume expansion (99%) compared to other Cu-P conversion anodes.
- The study provides a comprehensive analysis of Cu-P phase stability and electrochemical performance, facilitating further experimental investigation.
