Robust artificial HfO2/PEDOT:PSS polarity layer for increasing stability of Li metal anodes

Abstract

Li-metal shows great potential for use in rechargeable high-energy-density batteries. However, the formation of Li dendrites and the unstable solid-electrolyte interface on Li-metal remain obstacles to their commercialization. In this study, a HfO2 and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS, labeled as Hf-P) protective layer is formed on Li-metal to inhibit electrolyte degradation, suppress Li dendrite formation, and ensure high mechanical strength during cycling. Dendrite-free Li-metal anode can be achieved by forming a Hf-P protective layer, which allows the side reactions that occurs between the organic electrolyte and the Li-metal electrode to be controlled, resulting in uniform Li deposition. Furthermore, the Hf-P protective layer enhances the dielectric characteristics of the electrode and improves its mechanical strength and Li-ion conductivity. Consequently, Li|Li symmetric cell based on the protected anode exhibits superior electrochemical properties and effectively inhibits Li dendrite formation, resulting in a small overvoltage of 14 mV and stable cycling for 2000 h at 1 mA cm−2. Additionally, the LiNi0.5Mn0.3Co0.2O2 cathode-equipped Li-ion full cell displays constant capacity retention for up to 300 cycles. In order to stabilize Li-metal batteries, this study presents a novel method that uses protective layer consisting of HfO2 and PEDOT:PSS to efficiently inhibit Li dendrite growth.