4.85 V high-voltage lithium ion battery enabled by an in-situ formed Lewis acid-base complex multifunctional additive and nanocomposite electrodes

Abstract

Elevating the operating voltage of Lithium-ion battery (LIB) is key to enhance its energy density but challenging. Herein, we propose and demonstrate a new concept of introducing Lewis acid-base complex as multifunctional electrolyte additive for high-voltage LIBs, which is in-situ formed through the electron accepting-donating reaction between Lewis acid (fluoroethylene carbonate, FEC) and Lewis base (tris(trimethylsilyl) phosphite, TMSP). The combined multi-functionalities enable it to stabilize and clean the electrolyte, and be preferential oxidized/reduced to form robust F/P/Si-rich inorganic-organic hybrid cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) for protecting both LiNi_0.5Mn_1.5O₄ (LNMO) cathode and graphite (Gr) anode from continuous electrolyte decomposition and the dissolution of metal ions from LNMO cathode and inactive Li plating on Gr anode. In addition, carbon nanotubes (CNTs) and graphene (GN) are used as conductive additives to construct a three-dimensional (3D) internal conductive network for boosting the rate capability and cycling stability. The synergy from the complex and nanocomposites endows our LIBs with a high voltage of 4.85 V, a high energy and power density of 284.5 Wh kg⁻¹ and 2.8 kW kg⁻¹, and a long lifespan. This feasible approach represents a simple yet effective electrolyte engineering and electrode optimization strategy for fabricating high-voltage LIBs.