A Hauser-base modulated boron-based electrolyte empowering superior interfacial chemistry in rechargeable magnesium batteries

Abstract

Electrolytes with superior Mg plating/stripping performance and cathode compatibility through a simple synthetic pathway and affordable raw materials have become a long-term pursuit of rechargeable magnesium batteries (RMBs). Herein, an efficient Hauser-base modulated boron-based electrolyte TMPLB is proposed via a facile in-situ one-pot method that involves mixing intrinsic LiCl-containing Hauser-base TMPL (2,2,6,6-tetramethylpiperidinylmagnesium chloride lithium chloride complex) and Lewis acid B(Otfe)3 (tris(2,2,2-trifluoroethyl)borate) in tetrahydrofuran (THF). Nuclear magnetic resonance (NMR) results reveal that the TMPLB electrolyte is mainly composed of active cation [Mg2(μ-Cl)3·6THF]+ and anion [(TMP)B(Otfe)3]−. In addition to a conducive solid electrolyte interphase (SEI) formed on Mg, the in-situ generated robust cathode electrolyte interphase (CEI) on cycled Mo6S8 jointly endows excellent Mg2+ transfer kinetics and cycling stability. Specifically, Mo6S8||Mg full cells can be cycled for over 3000 cycles with a superior capacity retention of 88.2 mAh g−1 under 5 C. The TMPLB electrolyte paves an avenue for the building of stable electrode/electrolyte interfaces in future practical long-life RMBs.