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 Li xFePO4 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.
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