Stabilizing LiCoO2/Graphite at High Voltages with an Electrolyte Additive

The energy density of commercial Li-ion batteries (LIBs) using LiCoO2 has been subject to the limited access to the Li stored in CoO2 lattice, which is imposed partially by the instability of carbonate-based electrolyte at potential higher than 4.5 V. In this work, we report a novel approach to fully utilizing these extra Li via simultaneously stabilizing anode and cathode interfaces with a designed additive 4-propyl-[1,3,2]dioxathiolane-2,2-dioxide (PDTD), which strongly coordinate with Co ions dissolved in electrolytes while decomposing to form protective interphases on both cathode and anode surfaces. The Co ions present in the electrolyte deposit on anode in the form of the coordinate with PDTD, avoiding the formation of Co metal that will catalyze the reduction decomposition of the additive-free electrolyte. The presence of PDTD in electrolyte enables a higher charging potential of 4.45 V for LiCoO2/graphite cell, which significantly improved energy density and cycling stability of this cathode chemi...