Wet-Chemical Synthesis of 3D Stacked Thin Film Metal-Oxides for All-Solid-State Li-Ion Batteries.

Evert Van Den Ham,Sven Gielis,Peter Notten,An Hardy,Christophe Detavernier,Gilles Bonneux,Ken Elen,Felix Mattelaer,Giulia Maino,Marlies Van Bael,Wouter Marchal

doi:10.3390/ma10091072

Abstract

By ultrasonic spray deposition of precursors, conformal deposition on 3D surfaces of tungsten oxide (WO3) negative electrode and amorphous lithium lanthanum titanium oxide (LLT) solid-electrolyte has been achieved as well as an all-solid-state half-cell. Electrochemical activity was achieved of the WO3 layers, annealed at temperatures of 500 °C. Galvanostatic measurements show a volumetric capacity (415 mAh·cm−3) of the deposited electrode material. In addition, electrochemical activity was shown for half-cells, created by coating WO3 with LLT as the solid-state electrolyte. The electron blocking properties of the LLT solid-electrolyte was shown by ferrocene reduction. 3D depositions were done on various micro-sized Si template structures, showing fully covering coatings of both WO3 and LLT. Finally, the thermal budget required for WO3 layer deposition was minimized, which enabled attaining active WO3 on 3D TiN/Si micro-cylinders. A 2.6-fold capacity increase for the 3D-structured WO3 was shown, with the same current density per coated area.

Highlights

Finding smart solutions for sustainable energy harvesting and storage is often opted as the main challenge of the near future
Based on previous results using this approach [21], this study aims to investigate the stacking of tungsten oxide (WO3 ) as a negative electrode in combination with amorphous lithium lanthanum titanium oxide (Li3x La(2/3)−x TiO3, referred to as LLT) solid-electrolyte to compile a 3D all-solid-state half-cell
After evaporation of residual water from the precursor gel due to incomplete drying, a first weight loss is observed at 140 and 180 ◦ C with endothermal features. This is followed by two minor exothermal decomposition steps at 365 and 485 ◦ C

Summary

Introduction

Finding smart solutions for sustainable energy harvesting and storage is often opted as the main challenge of the near future. Contemporary Li-ion batteries suffer from a number of intrinsic issues, mostly related to the use of liquid electrolyte: (i) safety risks; (ii) limited lifetime; and (iii) operating temperature limitations. Efforts are made to tackle these issues by stabilizing polymer and gel-based electrolytes, in combination with contemporary battery design, increasing the thermal stability and lifetime of the battery [1,2]. These issues can be dealt with to a greater extent by adopting a solid-electrolyte, yielding an all-solid-state battery [3,4]. All-solid-state batteries suffer from intrinsic issues as well, due to the lower conductivity of the solid-electrolyte.

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Conclusion