Simultaneous modulation of cathode/anode and electrolyte interfaces via a nitrile additive for high-energy-density lithium-metal batteries.

Abstract

Nickel-rich layered oxides have great potential for commercial development applications, so it is critical to address their stability over long cycles. Ensuring long-term cycle stability relies heavily on the stability of the interface between the electrode and electrolyte in Li|LiNi0.8Co0.1Mn0.1O2 (NCM811) batteries. In this work, a denser, more stable and thinner nickel-rich cathode/electrolyte interface was constructed by electrolyte engineering with succinonitrile (SN) as an additive. The increase of organic compound content in the formed Ni-rich cathode/electrolyte interface can fully release the stress and strain generated during repetitive charge-discharge processes, and significantly reduce the irreversible phase transition during the nickel-rich cathode charge-discharge processes. Additionally, this interface impedes the breakdown of electrolytes and the dissolution of transition metals. Furthermore, the addition of SN additives also forms a more stable lithium metal anode/electrolyte interface. Notably, batteries containing SN additives (0.5, 1.0 and 1.5 wt%) show excellent electrochemical performance compared to base electrolytes. Particularly, the improvement is most significant with an SN addition of 1.0 wt%. After 250 cycles at 1C rate, the capacity retention rate of the battery improved by 32.8%. Thus, this work provides a new perspective for simultaneously constructing a stable interface of nickel-rich cathode and lithium metal anode with a high energy density in lithium metal batteries.