Strain tuned Li diffusion in LiCoO2 material for Li ion batteries: A first principles study

To improve the rate performance of the LiCoO2 cathode, it is essential to enhance its Li ion diffusion coefficient. From density functional theory calculations, we show that the Li ion migration energy barrier in LiCoO2 is sensitive to the strain applied to the lattice. The Li ion migration energy barrier decreases/increases substantially upon tensile/compressive stress applied along the c-axis direction, leading to the changes of the Li diffusion coefficient in several orders of magnitude at 300 K. Furthermore, strain applied in the ab-plane can also affect the Li diffusion in LiCoO2 as well, but the effect is not as obvious as strain applied along the c-axis direction. These results prompt a new way to tune the rate performance of LiCoO2.