KRICT transfer-prints a 15 µm LLZTO solid electrolyte layer over 120 cm² for solid-state cells

A team at the Korea Research Institute of Chemical Technology (KRICT) has developed a transfer printing process for a solid electrolyte based on the garnet-type oxide LLZTO, according to a release published by EurekAlert on 4 November 2026. The electrolyte layer is first made on a separate substrate and then transferred onto an electrode. The group, led by Yongku Kang and Myung-Soo Park, produced a layer with an average thickness of 15 µm and a deviation of about 1 µm over 6 × 20 cm, or 120 cm² eurekalert.orgEurekAlerteurekalert.orgOpen source ↗.

Why thin electrolyte layers are hard to make

Solid-state batteries use a solid electrolyte instead of a liquid one, which may lower fire risk and raise energy density. For high energy density the layer must be thinner than 20 µm and uniform over a large area. Freestanding films need 70–120 µm to avoid tearing. Coating a slurry directly onto an electrode is also problematic: the liquid can soak into the porous electrode, deforming it and making the thickness uneven eurekalert.orgEurekAlerteurekalert.orgOpen source ↗.

In the new process, the slurry is coated and dried on a PET-PDMS substrate. The finished thin layer is then pressed with a roller and transferred onto the electrode, like a sticker. The authors used Hansen solubility parameters to quantify affinity between materials. High affinity was chosen for the coating step so the slurry spreads evenly, and low adhesion for the transfer step so the dried layer detaches cleanly eurekalert.orgEurekAlerteurekalert.orgOpen source ↗.

Conductivity, cycling and heat tests

Direct coating onto an electrode gave film thicknesses of 10 to 25 µm even over a smaller area of 6 × 11 cm. At 25°C the hybrid electrolyte reached an ionic conductivity of 2.83 × 10⁻⁴ S/cm, about 50% above the 1.69 × 10⁻⁴ S/cm of a control with the same polymer electrolyte in a polyethylene (PE) separator. The Li⁺ transference number was 0.69 against 0.36 for the control, which the authors attribute to the LLZTO-rich layer acting as a continuous path for Li⁺ eurekalert.orgEurekAlerteurekalert.orgOpen source ↗.

After 100 charge-discharge cycles, the transfer-printed cell retained 83.6% of its capacity, versus 36.1% for the directly coated cell. In a pouch-cell test at 150°C for 2 hours 30 minutes, the transfer-printed cell kept a stable voltage. The PE separator cell developed an internal short circuit from separator shrinkage, and its voltage dropped sharply after about 10 minutes eurekalert.orgEurekAlerteurekalert.orgOpen source ↗.

The study appeared in Advanced Functional Materials in September 2026. Seul Gi Chu is the first author; Kang and Park are corresponding authors eurekalert.orgEurekAlerteurekalert.orgOpen source ↗.