Towards a solution deposited 3D thin-film Li-ion battery

Abstract

Lithium ion batteries (LIB) have important applications for mobile electronics, electric vehicles or storage of renewable energy. Conventional LIB are using powder based electrodes and a liquid electrolyte, and provide high capacity. Alternatively, thin film LIB provide higher power and employs solid electrolytes, which guarantees safety. To combine the advantages of both, 3D thin film batteries have been proposed, and devices up to half cells have been deposited using vacuum based methods because conformality is of the utmost importance. Here, we demonstrate a solution based deposition process for 3D thin film battery components, including anode, cathode and solid electrolytes as well as half cells. The methodology is based on an optimized ultrasonic spraydeposition process and a water based precursor solution containing citrate complexes, with finetuned surface tension and gelation upon contact with the substrate. In this way complete coating of the structures was achieved with a high degree of conformality. We present results on WO3, Li4Ti5O12, LiMn2O4, Li3xLa(2/3)-x(1/3)-2xTiO3 which are relevant components for a 3D thin film battery. The morphology, crystal structure, chemical purity and electrochemical properties are characterized. Furthermore, half cell stacks are deposited as well. In conclusion, 3D structures were coated by ultrasonically spray depositing an aqueous solution-gel precursor, yielding electrochemically active electrodes, as well as half cell stacks. The method is promising to other application areas such as photocatalysis or capacitors as well.

We acknowledge the IWT project SBOSOSLION and UHasselt (BOF-IOF) for financial support.