A charge-density-based general cation insertion algorithm for generating new Li-ion cathode materials

Jimmy-Xuan Shen,Kristin A Persson,Matthew Horton

doi:10.1038/s41524-020-00422-3

Jimmy-Xuan Shen, Kristin A Persson + Show 1 more

Open Access

https://doi.org/10.1038/s41524-020-00422-3

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Abstract

Future lithium (Li) energy storage technologies, in particular solid-state configurations with a Li metal anode, opens up the possibility of using cathode materials that do not necessarily contain Li in its as-made state. To accelerate the discovery and design of such materials, we develop a general, chemically, and structurally agnostic methodology for identifying the optimal Li sites in any crystalline material. For a given crystal structure, we attempt multiple Li insertions at symmetrically in-equivalent positions by analyzing the electronic charge density obtained from first-principles density functional theory. In this report, we demonstrate the effectiveness of this procedure in successfully identifying the positions of the Li ion in well-known cathode materials using only the empty host (charged) material as guidance. Furthermore, applying the algorithm to over 2000 candidate cathode empty host materials we obtain statistics of Li site preferences to guide future developments of novel Li-ion cathode materials, particularly for solid-state applications.

Highlights

The need for rechargeable energy storage with higher energy density and longer operating life-time is a technical challenge for a future, carbon-neutral society
The solid-state electrolyte enables the use of a metal anode, which eliminates the need for a cathode as the source of the working ion and opens up the playing field to a broader chemical and structural space, considering different application specifics, beyond those traditionally tailored for portable electronics
To demonstrate the insertion algorithm, we apply it to two well-known cathode materials: lithium manganese oxide (LMO) (LixMnO2) in the λ phase and lithium iron phosphate (LixFePO4, or LFP) in the olivine phase, which provides two very different testing materials

Summary

INTRODUCTION

The need for rechargeable energy storage with higher energy density and longer operating life-time is a technical challenge for a future, carbon-neutral society. As of Feburary 2020, the Materials Project includes 125,134 material entries, 21,584 of which contain at least one transitionmetal redox element in addition to either oxygen or sulfur but none of the following possible working ions—Li+, Ca2+, Mg2+, and Na+ These candidate intercalation host materials cover 6862 distinct combinations of atomic species, which we call chemical systems. We present an algorithmic framework that suggests possible insertion sites in any crystal structure using the charge density of the host material. We attempt Li insertions into 2271 candidate cathode materials available within the Materials Project, which allows us to systematically investigate the effect of inserting Li into different chemical systems as well as the local coordination preference of Li, across a large diverse set of chemistries and structures. Statistics of Li insertion site preferences and chemical environments are presented

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