Effect of surface carbonates on the cyclability of LiNbO3-coated NCM622 in all-solid-state batteries with lithium thiophosphate electrolytes

A-Young Kim,Florian Strauss,Timo Bartsch,Jun Hao Teo,Jürgen Janek,Torsten Brezesinski

doi:10.1038/s41598-021-84799-1

Abstract

While still premature as an energy storage technology, bulk solid-state batteries are attracting much attention in the academic and industrial communities lately. In particular, layered lithium metal oxides and lithium thiophosphates hold promise as cathode materials and superionic solid electrolytes, respectively. However, interfacial side reactions between the individual components during battery operation usually result in accelerated performance degradation. Hence, effective surface coatings are required to mitigate or ideally prevent detrimental reactions from occurring and having an impact on the cyclability. In the present work, we examine how surface carbonates incorporated into the sol–gel-derived LiNbO3 protective coating on NCM622 [Li1+x(Ni0.6Co0.2Mn0.2)1–xO2] cathode material affect the efficiency and rate capability of pellet-stack solid-state battery cells with β-Li3PS4 or argyrodite Li6PS5Cl solid electrolyte and a Li4Ti5O12 anode. Our research data indicate that a hybrid coating may in fact be beneficial to the kinetics and the cycling performance strongly depends on the solid electrolyte used.

Highlights

While still premature as an energy storage technology, bulk solid-state batteries are attracting much attention in the academic and industrial communities lately
In this work we studied the effect that the amount of carbonate incorporated into the L iNbO3-based surface coating on NCM622 cathode material has on the cycling performance of pelletized solid-state battery (SSB) cells with an LTO anode
The uncoated and coated NCM622 cathode materials were electrochemically tested at 25 °C in cells with either β-Li3PS4 or Li6PS5Cl and Super C65 carbon black as solid electrolyte and electronically conductive additive, respectively

Summary

Introduction

While still premature as an energy storage technology, bulk solid-state batteries are attracting much attention in the academic and industrial communities lately. We examine how surface carbonates incorporated into the sol– gel-derived LiNbO3 protective coating on NCM622 [Li1+x(Ni0.6Co0.2Mn0.2)1–xO2] cathode material affect the efficiency and rate capability of pellet-stack solid-state battery cells with β-Li3PS4 or argyrodite Li6PS5Cl solid electrolyte and a Li4Ti5O12 anode. Substituting an inorganic (superionic) solid electrolyte for the liquid electrolyte in LIBs is a potentially viable strategy to increase energy density and minimize safety risks due to cell failure[4,5,6] Lithium thiophosphates, such as argyrodite Li6PS5Cl, are among the most promising solid electrolytes because of their high ionic conductivity at room temperature and favorable ductility properties[7,8,9,10,11,12,13,14,15,16,17]. The surface-treated samples were characterized using different methods and electrochemically tested in pellet-stack SSB cells with a Li4Ti5O12 (LTO) anode and either β-Li3PS4 or L i6PS5Cl as solid electrolyte

Methods

Results

Conclusion