Investigation of Interfacial Behavior of Ni-Rich NCM Cathode Particles in Sulfide-Based Solid-State Electrolyte

Abstract

All-solid-state batteries (ASSBs) are currently investigated as a future battery technology with conventional layered cathode materials because they can offer benefits in the gravimetric and volumetric energy densities compared to flammable liquid electrolyte lithium-ion batteries with graphite intercalation anode. The solid electrolyte is believed to suppress dendritic growth and low Coulombic efficiency on the lithium metal anode side, which are the key issues for the use of a lithium metal electrode in conventional batteries with liquid electrolyte. Moreover, layered transition metal oxides such as LiNixCoyMnzO2 (NCM, 0 < x, y, z < 1) are one of the most promising positive electrode active material candidates being developed to increase the energy density. In particular, recent studies have shown a tendency to decrease the cobalt content and increase the nickel content to increase energy density and price competitiveness, so high-nickel NCM can be the optimal material suitable for this purpose. However, the remaining interfacial challenges of the cathode / solid electrolyte interface still need to be solved.Herein, we investigated the kinetics such as charge transfer resistance at the interface between high nickel (Ni0.94) NCM particles and argyrodite (Li6PS5Cl) solid electrolytes using the microcavity electrode with the negative and positive pulsed current measurement technique and compared with liquid electrolytes using the same manner measurement technique. The cavity-electrode system is adopted to analyze the electrochemical properties of active particles and electrolytes confined in the cavity to exclude the effects of surrounding interfaces, barriers, and side reactions caused by battery components around the electrodes and the impact of loading and current collectors of the composite electrode. Therefore, understanding the electrode-electrolyte interface between cathode active particles and solid electrolytes is crucial for theoretical studies on the interfacial phenomenon in solid electrolyte batteries.