Spatially resolved modelling and characterization of (de-)intercalation in Li-Ion battery materials: DFT calculations (SP1)
Lithium ion battery materials undergo significant volume change during charging and discharging, which, dependent on the material, is connected to a change of the crystallographic structure. This causes mechanical fatigue which deteriorates the performance of the batteries. This project is part of a joint effort within the DFG priority program SPP1473 WeNDeLIB (http://www.spp1473.kit.edu/). It aims on investigating, spatially and temporally resolved, the evolution of the lithium distribution and phase transitions during (dis)charging. The project is embedded in a close coupling between theory and experiment with focus on Li-Fe-P-O as a promising class for future low-cost electrode materials.The theoretical part uses ab initio calculations of structural stability and diffusion coefficients in Li-Fe-P-O systems that will be combined with phase field simulation of charge transfer at the anode-electrolyte interface, volume expansion during interdiffusion, phase transformation and mechanical stress. The possible device improvement gained by shrinking microstructural elements to the nanometer regime will be covered by including surface- and interface-related materials characteristics. The joint project is expected to give a complete and, for the first time, spatially resolved picture of the complex mechanisms of lithium transport and phase transitions in nanograined battery materials. From the combinatorial investigations by experiment and theory, a route to improved materials will be pinpointed.