STRAIN INDUCED ENHANCED MIGRATION OF POLARON AND LITHIUM ION IN λ-MnO2
The dynamic properties of λ- MnO2 under strain can be different to normal conditions as lithium storage material. Results from first-principles calculations show that compressive strain will enhance the electrical conductivity and lithium ion diffusion coefficient simultaneously. We show that 7% compressive strain applied along the (011) direction leads to about two orders of magnitude increase in both the electrical conductivity and Li diffusion coefficient under room temperature. 7% compressive strain applied along the (111) direction will increase the Li diffusion coefficient by five orders of magnitude. These results are important to experimental and industrial preparation and design of λ- MnO2 materials when interfaces are involved. The physical mechanism behind the strain induced improvement of the dynamic performance is discussed.