Overpotential-Dependent Phase Transformation Pathways in Lithium Iron Phosphate Battery Electrodes

2010 ◽  
Vol 22 (21) ◽  
pp. 5845-5855 ◽  
Author(s):  
Yu-Hua Kao ◽  
Ming Tang ◽  
Nonglak Meethong ◽  
Jianming Bai ◽  
W. Craig Carter ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Lithium Iron Phosphate ◽  
Iron Phosphate ◽  
Transformation Pathways

scholarly journals A mechanism of defect-enhanced phase transformation kinetics in lithium iron phosphate olivine

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Liang Hong ◽  
Kaiqi Yang ◽  
Ming Tang
Keyword(s):  
Phase Transformation ◽  
Surface Reaction ◽  
Lithium Iron Phosphate ◽  
Active Surface ◽  
Iron Phosphate ◽  
Active Surface Area ◽  
General Strategy ◽  
Transformation Rate ◽  
Kinetic Regime ◽  
Antisite Defects

AbstractAntisite defects are a type of point defect ubiquitously present in intercalation compounds for energy storage applications. While they are often considered a deleterious feature, here we elucidate a mechanism of antisite defects enhancing lithium intercalation kinetics in LiFePO4 by accelerating the FePO4 → LiFePO4 phase transformation. Although FeLi antisites block Li movement along the [010] migration channels in LiFePO4, phase-field modeling reveals that their ability to enhance Li diffusion in other directions significantly increases the active surface area for Li intercalation in the surface-reaction-limited kinetic regime, which results in order-of-magnitude improvement in the phase transformation rate compared to defect-free particles. Antisite defects also promote a more uniform reaction flux on (010) surface and prevent the formation of current hotspots under galvanostatic (dis)charging conditions. We analyze the scaling relation between the phase boundary speed, Li diffusivity and particle dimensions and derive the criteria for the co-optimization of defect content and particle geometry. A surprising prediction is that (100)-oriented LiFePO4 plates could potentially deliver better performance than (010)-oriented plates when the Li intercalation process is surface-reaction-limited. Our work suggests tailoring antisite defects as a general strategy to improve the rate performance of phase-changing battery compounds with strong diffusion anisotropy.

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