Cathode Electrolyte Interface Stabilization and Transition Metal Dissolution Mitigation Via Sodium Boron Salt Utilization

Abstract

Renewable energy storage devices have revolutionized the application of modern electronics and electrical infrastructures. The ever-increasing demand for large-scale energy storage has steered investigative interest to the rising potential of cost-efficient sodium ion batteries. However, the long-term cycling instability of cathode materials impedes wide-scale commercialization of sodium ion batteries. The interfacial reactions between the cathode and electrolyte has been shown to lead to prevalent surface reconstruction, transition metal dissolution, and the formation of intragranular nanocracks in the cathode particle, reducing overall cathode stability and cycling performance. Transitional metal dissolution can play a significant role in in performance degradation and further accelerating cathode particle instability. Investigating and improving the surface chemistry between the cathode and electrolyte is paramount to improving cathode stability and performance. We have designed a series of electrolytes that utilize select sodium boron salts that can passivate the O3-NaNi1/3Fe1/3Mn1/3O2 cathode and help form a robust cathode-electrolyte interphase (CEI). Through the utilization, and combination, of the sodium boron electrolytes, we observe improved cathode stability and long-term performance. We demonstrate enhanced cathode-electrolyte stability and cyclability at various temperatures ranging from 0°C - 45°C. Through improving the cathode surface passivation, we reduce interfacial reactions and observe a mitigation of transitional metal dissolution and migration from the cathode to separator or anode. Through this study, we demonstrate the importance of understanding the interfacial cathode-electrolyte surface chemistries and that there is further room for improving the electrolyte formulation for sodium layered oxide cathode materials. L. Mu, X. Feng, R. Kou, Y. Zhang, H. Guo, C. Tian, C.J. Sun, X.W. Du, D. Nordllund, H.L. Xin, and F. Lin Adv. Energy Mater., 8, 1801975 (2018)R. Jung, F. Linsenmann, R. Thomas, J. Wandt, S. Solchenbach, F. Maglia, C. Stinner, M. Tromp, H.A. Gasteiger, J. Electrochem. Soc., 166, A378–A389 (2019)J. Chen, Z. Huang, C. Wang, S. Porter, B. Wang, W. Lie, H.K. Liu Chem. Commun., 51, 9809–9812 (2015). The work was supported by the Virginia Tech Department of Chemistry Startup Funds, 4-VA Collaborative Research, and National Science Foundation (No. CBET-1912885). Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-76SF00515. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory, under Contract No. DE-AC02- 06CH11357.