Modeling intercalation chemistry with multiple redox reactions by sparse lattice model*

Disordered rocksalt materials are the most promising earth-abundant cathode materials for Li-ion batteries, and as such can enable scaling of Li-ion energy storage to many TWh/year production. Such modern battery materials can contain a large number of elements with substantial site disorder, and their state of short-range ordering has been shown to be critical for their performance.  Ab-initio modeling of the configurational degrees of freedom increases exponentially with the number of species included. The problems to apply cluster expansion techniques include: (1) how to generate lattice models without over-fitting; (2) how to properly sample the configurational space in ionic systems with charge-neutrality.

 

To address these, we will demonstrate two novel methods to approach the multi-component space of DRX: (1) applying L0L2-norm regularized regression with structural hierarchy to construct a robust cluster expansion Hamiltonian. (2) implementing grand-canonical Monte Carlo to sample charge-balanced ionic configurations. We apply these approaches to compute the voltage profile of Li_1.3-xMn_0.4Nb_0.3O_1.6F_0.4, and demonstrate how Mn and oxygen contributes to the redox potential as Li is intercalated.