TEM Study of Fracturing in Spherical and Plate-like LiFePO[sub 4] Particles

An investigation of fracturing in particles as a function of the particle morphology and history is presented. Two types of samples, one subjected to electrochemical cycling and another to chemical delithiation, are compared. We observe the formation of microfractures parallel to low indexed lattice planes in both samples. The fracture surfaces are predominantly parallel to (100) planes in the chemically delithiated powder and (100) and (010) planes in the electrochemically cycled powder. A consideration of the dislocations' stress fields shows that particle geometry plays an important role in the observed behavior.