Particle-Size Effects on the Entropy Behavior of a LixFePO4 Electrode

The particle‐size effects on the thermodynamic properties and kinetic behavior of a LixFePO4 electrode have a direct influence on the electrode properties. Thus, the development of high‐performance Li‐ion batteries containing a LixFePO4 cathode requires a complete understanding of the reaction mechanism at the atomic/nano/meso scale. In this work, we report electrochemical calorimetric and potentiometric studies on LixFePO4 electrodes with different particle sizes and clarify the particle‐size effect on the reaction mechanism based on the entropy change of (de)lithiation. Electrochemical calorimetry results show that a reduction in particle size shrinks the miscibility gap of LixFePO4 while potentiometric measurements demonstrate that the LixFePO4 particles equilibrate into either a kinetically metastable state or a thermodynamically stable state depending on the particle size. Size matters! Particle‐size effects on the entropy behavior of a LixFePO4 electrode are studied by electrochemical calorimetry and potentiometric measurements. Under open‐circuit conditions, the LixFePO4 particles equilibrate into either a kinetically metastable state or a thermodynamically stable state depending on the particle size.