Electrolytes for high-voltage Li batteries

LIBs have flourished for 30 years with the energy density tripled since the 1990s thanks to the coupling of layered cathodes, graphite, and carbonate electrolytes. To further promote the energy density of LIBs, the most promising strategies are to enhance the cut-off voltage of the prevailing cathodes or explore novel high-capacity and high-voltage cathode materials, and also replace graphite anode with Si/Si-C or Li metal for anodes. However, the commercial ethylene carbonate (EC)-based electrolytes with relatively low anodic stability of ~ 4.3 V vs. Li+/Li cannot sustain high-voltage cathodes. Bottleneck restricting the electrochemical performance in Li batteries has been veered to the new electrolyte compositions catered for aggressive next-generation cathodes and Si/Si-C or Li metal anodes, since the oxidation-resistance of the electrolytes and the in situ formed cathode electrolyte interphase (CEI) layers at the high-voltage cathodes and solid electrolyte interphase (SEI) layers on anodes critically control the electrochemical performance of these high-voltage Li batteries. In this seminar, I will present a comprehensive and in-depth overview of the recent advances, fundamental mechanisms, scientific challenges, and design strategies for the novel high-voltage electrolyte systems, especially focused on stability issues of the electrolytes, the compatibility and interactions between the electrolytes and the electrodes, and reaction mechanisms.