A Chemical Map of Nasicon Electrode Materials for Sodium-Ion Batteries

Abstract

Sodium (Na)-ion batteries are among the most promising devices to supersede the present Li-ion batteries in heavy-duty and smart grid applications. This is mostly encouraged by the lower cost of N-metal and its worldwide availability[1], as well as the possibility of replacing expensive copper current collectors by aluminium ones. In the recent years, many electrode materials have been discovered and designed to enhance the energy density of Na-ion batteries. Among those electrode materials, the Natrium Superionic CONductor (NaSICON)[2] prototype structure are known for their wide range of electrochemical potentials, high ionic conductivities, and most importantly their structural and thermal stabilities [3–5].In this talk we will explored the chemical space of NaSICON structured materials, NaxMM’(PO4)3 where M, M’(Ti, V, Cr, Mn, Fe, Co & Ni), using ab initio density functional theory (DFT) and thermodynamic approaches [6]. We have analysed the thermodynamic stabilities, Na+ intercalation voltages and corresponding redox pairs for 28 combinations of M & M’ and the full Na concentration range (i.e., 1 ≤ x ≤ 4). This study enabled us to pinpoint anomalies in exiting experimental reports as well as to identify new NaSICON compositions that can enable the extractions of three Na ions (e.g., NaxMn2(PO4)3 and NaxVCo(PO4)3, etc). Furthermore, the calculated quaternary phase diagrams Na-Mn-P-O could show the stability of NaxMn2(PO4)3, while analogues phase diagrams, i.e., Na-Ni-P-O and Na-Co-P-O explained the origin of the suspected instability of Ni and Co-based NaSICONs. We realized that the presence of Jahn-Teller active transition metals ions enhances the voltages but limits the practicality of entire chemical space for cathodic applications.[1] D. Larcher and J. M. Tarascon, Nat. Chem., 2015, 7, 19.[2] J. B. Goodenough , H. Y. P. Hong and J. A. Kafalas, Mater. Res. Bull., 1976, 11 , 203[3] W. Zhou , L. Xue , X. Lü , H. Gao , Y. Li , S. Xin , G. Fu , Z. Cui , Y. Zhu and J. B. Goodenough , Nano Lett., 2016, 16 , 7836[4] J. Wang , Y. Wang , D. Seo , T. Shi , S. Chen , Y. Tian , H. Kim and G. Ceder , Adv. Energy Mater., 2020, 10 , 1903968[5] Z. Deng , G. Sai Gautam , S. K. Kolli , J.-N. Chotard , A. K. Cheetham , C. Masquelier and P. Canepa , Chem. Mater., 2020, 32 , 7908[6] Baltej Singh, Z. Wang, S. Park, G. S. Gautam, J. N. Chotard, L. Croguennec, D. Carlier, A. K. Cheetham, C. Masquelier and P. Canepa. J. Mater. Chem. A, 9, 281-292 (2021)