By Josh Perry, Editor
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A team of researchers from the Toyohashi University of Technology (Japan) have successfully fabricated a lithium trivanadate (LVO) cathode thick film on a garnet-type oxide solid electrolyte through aerosol disposition, which demonstrated a large, reversible charge and discharge capacity.

SEM image of a fractured cross-sectional surface of the LVO electrode fabricated on LLZTO garnet by AD. Corresponding elementary mapping for V, La, and Zr is also shown.
(Toyohashi University of Technology)

According to a report published by Phys.org, the cathode capacity was as high as 300 mAh/g and it showed good cycling stability at 100°C, which indicates the potential for chemically-stable, oxide-based, solid-state lithium batteries.

Solid electrolytes are currently being studied for their potential application in electric vehicle batteries and other possible uses and oxide-based solid electrolytes have the benefit of being easy to handle and chemically-stable.

“The garnet-type fast Li+ conducting oxide, Li7-xLa₃Zr_2-xTaxO₁₂ (x = 0.4-0.5, LLZTO), is considered as a good candidate for SE because of its good ionic conducting property and high electrochemical stability,” the article explained. The drawback is that high-temperature sintering is needed for densification and that limits the oxide to only a few electrode materials.

Aerosol disposition, which was used in this study, can be performed at room temperature.

“By controlling the particle size and morphology, dense ceramic thick films can be fabricated on various substrates without thermal treatment,” the article continued. “This feature is attractive in the fabrication of oxide-based solid-state batteries because various electrode active materials can be selected and formed on SE with no thermal treatment.”

The article added, “To fabricate a dense LVO film on an LLZTO pellet, the size of the LVO particles was controlled by ball-milling. As a result, an LVO thick film with a thickness of 5-6 μm was successfully fabricated on LLZTO at room temperature. The relative density of the LVO thick film was approximately 85 percent. For the electrochemical characterization of the LVO thick film as a cathode, Li metal foil was attached on the opposite end face of the LLZTO pellet as an anode to form an LVO/LLZTO/Li structured solid-state cell. The galvanostatic charge (Li+ extraction from LVO) and discharge (Li+ insertion into LVO) properties in an LVO/LLZTO/Li all-solid-state cell were measured at 50 and 100°C.”

The results of the study indicate that LVO can be used as a high-capacity cathode in oxide-based solid-state batteries.

The research was recently published in Materials. The abstract read:

“We fabricated lithium trivanadate LiV₃O₈ (LVO) film electrodes for the first time on a garnet-type Ta-doped Li₇La₃Zr₂O₁₂ (LLZT) solid electrolyte using the aerosol deposition (AD) method. Ball-milled LVO powder with sizes in the range of 0.5–2 µm was used as a raw material for LVO film fabrication via impact consolidation at room temperature.

“LVO film (thickness = 5 µm) formed by AD has a dense structure composed of deformed and fractured LVO particles and pores were not observed at the LVO/LLZT interface. For electrochemical characterization of LVO film electrodes, lithium (Li) metal foil was attached on the other end face of a LLZT pellet to comprise an LVO/LLZT/Li all-solid-state cell. From impedance measurements, the charge transfer resistance at the LVO/LLZT interface is estimated to be around 10³ Ω cm² at room temperature, which is much higher than at the Li/LLZT interface.

“Reversible charge and discharge reactions in the LVO/LLZT/Li cell were demonstrated and the specific capacities were 100 and 290 mAh g⁻¹ at 50 and 100 °C. Good cycling stability of electrode reaction indicates strong adhesion between the LVO film electrode formed via impact consolidation and LLZT.”