Accelerating the Discovery of Multivalent Cathode Materials Via High-Throughput First-Principles Calculations

Batteries that shuttle multi-valent ions such as Mg²⁺ and Ca²⁺ ions are promising candidates for achieving higher energy density than available with current Li-ion technology. Finding electrode materials that reversibly store and release these multi-valent cations is considered a major challenge for enabling such multi-valent battery technology. In this work, we employ the recent advances in high-throughput first-principles calculations¹ to design and evaluate multivalent intercalation cathode materials so that we are able to quickly seek and assess the feasibility of multi-valent insertion cathodes from an in silico big data approach prior to experimental synthesis and characterization. It is our hope that our research provides general guidelines for multi-valent cathode material engineering and moreover, can greatly expedite the material discovery process.

We use density functional theory calculations (VASP code) combined with the robust high-throughput infrastructure¹ (pymatgen, pymatpro and FireWorks codes) to automatically calculate and analyze the properties and viabilities of possible multivalent cathode compounds. Based on the calculated results, we estimate the insertion voltage, capacity, thermodynamic stability and thermal stability of charged and discharged states. Therefore, the compounds with both good energy storage capability and superior structural stability can be identified as promising candidate materials for future experimental investigation and validation. To date, we have calculated and evaluated over 1800+ newly designed structures with five possible working ions (Mg, Ca, Zn, Y, Al). In general, we find that multivalent cathodes exhibit lower voltages compared to Li cathodes; the voltages of Ca coumpounds are ~0.2-0.5V higher than those of Mg compounds; Zn compounds usually have much lower voltage (Fig. 1).

 As a showcase, we systemically evaluate the theoretical performance of the spinel structure host with the general formula AB₂O₄ across a matrix of chemical compositions spanning A={Al, Y, Mg, Ca, Zn} and B={Ti, V, Cr, Mn, Fe, Co, Ni} for multivalent cathode applications.² As shown in Fig 2, considering all computed properties, Mn₂O₄ spinels are particularly interesting due to their stability. Among the divalent cations, both Mg²⁺ and Ca²⁺ may potentially be mobile in the spinel structure^2,3, warranting further experimental and computational investigation (particularly at small particle sizes). Mixed spinel structures provide a promising avenue, as the Ni^4+/3+ and Co^4+/3+ show higher voltage than the Mn^4+/3+ redox couple.

Acknowledgement: This work was supported by Joint Center for Energy Storage Research (JCESR) and the infrastructure and algorithmic was supported by the Materials Project (BES DOE Grant No. EDCBEE). We also thank NERSC for providing computation resources.

References

[1] A. Jain, S.P. Ong, G. Hautier, W. Chen, W.D. Richards, S. Dacek, S. Cholia, D. Gunter, D. Skinner, G. Ceder, and K.A. Persson, “The Materials Project: A materials genome approach to accelerating materials innovation.” APL Materials, 1, 011002 (2013)

[2] M. Liu, Z. Rong, R. Malik, P. Canepa, A. Jain, G. Ceder, and K.A. Persson, “Spinel Compounds as Multivalent Battery Cathodes: A Systematic Evaluation Based on ab initio Calculations” Submitted.

 [3] Z. Rong, R. Malik, P. Canepa, S.G. Gopalakrishnan, M. Liu, A. Jain, K.A. Persson, G. Ceder, “Materials Design Rules for Multi-Valent Ion Mobility in Intercalation Structures” In preparation.