Cycle Life Strain Reduction and Defect Elimination

1 Cycle Life Strain Reduction and Defect Elimination 

There are a number of reasons for the enhanced cycle life in nanoscale materials. First, the relatively open structure of nanoscale materials seems capable of accommodating a large volume expansion during lithiation. Secondly, the conventional mechanisms for microstructural damage are often absent in nanoscale materials. Dislocations are usually unstable in crystals with nanoscale dimensions ( 20 nm) due to image forces, which attract the dislocation to the surface. For brittle materials such as silicon and 

The fracture toughness, Ki., and yield strength, a, in polycrystalline silicon are approximately 0.751 MPa m / and 1.1 GPa, respectively These values yield a critical size of 300 nm for silicon and a roughly similar value for germanium, which has comparable material properties. The size dependence of fracture, was recently verified by the direct observation of lithiation of single particles. 

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