Advanced Electrolyte Stabilizing Ultrahigh-Nickel Layered Oxide Cathode in High-Voltage Lithium Metal Batteries

Abstract

To achieve batteries with high specific energy, long cycle life and low cost, the promising approach is to use lithium (Li) metal as anode and nickel (Ni)-rich/cobalt (Co)-less layered oxides as cathode. When the Ni content in the cathode is increased to an ultrahigh level (Ni ≥ 0.9), more specific energy can be obtained from the capacity contribution and high redox potential of Ni3+/Ni4+. Therefore, high-voltage Li metal batteries with ultrahigh-Ni layered oxide cathodes will offer a great opportunity in boosting the energy density of battery systems for applications in electrical vehicles. However, increasing Ni content intrinsically faces a dilemma between specific capacity and electrochemical cyclability for the cathode materials because of the aggressive side reactions of electrolyte on the highly reactive Ni surface. Here, we report an advanced electrolyte to enable high stability with both the reactive Li metal anode and an ultrahigh-Ni cathode LiNi0.94Co0.06O2 (NC), via the in-situ formation of a robust and conductive Li/electrolyte interphase and a protective and stable cathode/electrolyte interphase. Thus, the Li||NC cells with the advanced electrolyte can deliver a high discharge capacity of about 210 mAh g−1 and an excellent capacity retention of 81.4 % after 500 cycles at 25 °C in the voltage range of 2.8 - 4.4 V at 1C cycling rate (1.5 mA cm-2), which significantly outperform the cells using the conventional LiPF6-based electrolyte. This work provides a viable path to the successful application of ultrahigh-Ni cathode in high energy-density Li metal batteries. More detailed information will be given at the presentation.