Toward the Development of Sustainable Sodium Ion Battery

Recently, there has been a pressing demand for massive energy storage so as to enable the development of electric vehicles and facilitate the use of renewable energies. Li-ion batteries, which have already conquered the portable electronic market, are penetrating the EV’s market and stand as a serious contender for grid-related applications. Therefore, their performances must be improved cost-wise while preserving their energy density and safety attributes. This calls either to design new and high energy density materials based on abundant elements which can be synthesized via eco-compatible processes or the exploration of alternative technologies. Numerous alternative technologies such as Li-air, Li/S or Na-ion are presently considered. The last technology, will be the focus of the present report. There are several reasons for that: i) sodium resources are in principle unlimited, evenly distributed worldwide and their cost is extremely low; ii) Na does not alloy with Al enabling the use of cheap Al current collectors; last but not least iii) Na has similar intercalation chemistry to that of Li. Moreover, sodium has already been successfully implemented in today’s commercialized high temperature Na/S 1 cells for MW size electrochemical energy storage systems and for Na/NiCl 2 ZEBRA-type systems 2 for electric vehicles. Based on both our present understanding of this technology and recent research advances, done worldwide and in our group, at the electrode/electrolyte level we have reached confidence, from safety data regulation sheets, that making Na-ion batteries could present 20-30% cost reduction per kWh as compared to Li-ion technology. To secure such an optimism we launched a French project, involving several partners, aiming to benchmark the Na-ion secondary batteries in terms of sustainability, cost, safety and performances building 18650 and pouch cells. We initially focused on the Sb//1M NaPF 6 //Na 3 V 2 (PO 4 ) 2 F 3 Na-ion technology based on the expertise being developed in the groups forming the consortium on Na 3 V 2 (PO 4 ) 2 F 3 , 3 Electrolyte 4 and Sb alloys 5 . Fundamental studies on the materials processing and electrodes optimization will be first presented. Then, their stability with respect to various electrolytes formulations based on various carbonates solvents and additives (FEC and/or VC) will be discussed in terms of SEI layer formation in both half and complete cells. At last, the performances of a prototype battery (18650 type cell, and pouch cell) together with a preliminary cost estimate will be discussed. Other electrochemical results such as power rate performances and battery hazard analyses will be presented as well. References: [1] J Broadhead - US Patent 4,054,728, 1977. [2] B.L. Ellis, L.F. Nazar, Current Opinion in Solid State and Materials Science, 16 (2012) 168- 177. [3] A. Ponrouch, R. Dedryvère, D. Monti, A.E. Demet, J.M. Ateba Mba, L. Croguennec, C. Masquelier, P. Johansson and M.R. Palacin, Energy & Environmental Science 2013, 6(8), 2361−2369. [4] A. Ponrouch, E. Marchante, M. Courty, J.-M. Tarascon, M.R. Palacin, Energy & Environmental Science, 5 (2012) 8572-8583. [5] A. Darwiche, C. Marino, M.T. Sougrati, B. Fraisse, L. Stievano, L. Monconduit, Journal of the American Chemical Society, 134 (2012) 20805-20811.