Norbornenic anhydride as versatile additive optimizing interphases to enable high-performance LiNi0.8Co0.1Mn0.1O2/Li batteries

Abstract

Optimizing the electrode/electrolyte interface structure is the key to realizing high-energy-density Li-metal batteries (LMBs) with nickel-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode. Herein, a versatile additive, norbornene dicarboxylic anhydride (NA), is dedicated to constructing robust interphase layers in NCM811ǁLi batteries. Theoretical calculations and experimental results show that NA induces the formation of thin and stable cathode-electrolyte interface (CEI) / solid-electrolyte interface (SEI) films at the electrodes’ surfaces. The NA-induced CEI film on the cathode effectively protects NCM811 and improves its structural stability during long-term cycling, thus avoiding the material rupture and the dissolution of transition metals. On the other hand, the SEI film on the anode also enhances the performances of interface between electrolyte and Li-metal anode. A LiǁLi symmetric cell with NA exhibits excellent cycling stability at a current density of 1.0 mA cm−2 for cycling 400 h. Furthermore, the molecular dynamics simulations verify that NA additive influences the desolvation behavior of Li+ and increases transport kinetics of Li+ on the electrode/electrolyte interfaces. Therefore, the NCM 811ǁLi battery containing NA additive obtains a high capacity retention of 78.77 % after 200 cycles with a coulombic efficiency of 99.5 %.

Keywords

• Lithium metal batteries
• Norbornene dianhydride
• Electrolyte additive
• Interphases
• Nickel-rich cathode