The processing of garnet-type solid-state electrolytes
remains
challenging as densification conventionally requires high sintering
temperatures and long processing times, which can result in severe
Li loss, the formation of secondary phases, and thus high porosity
and low ionic conductivity. Here, we report an ultrafast sintering
method based on CO2 laser scanning with the assistance
of a heating stage. We demonstrate the rapid densification of low-packing-density
Li6.4La3Zr1.4Ta0.6O12 (LLZTO) films, which are difficult to densify by conventional
furnace sintering methods. This unique approach has three fingerprint
characteristics: (1) mitigation of Li loss through ultrafast sintering
(dwelling time ≪1 s); (2) a unique anisotropic shrinkage behavior
that greatly reduces film thickness; (3) wave-like surface topology
from point scanning strategy that enables 3D interfacial contacts
with electrode materials. Herein, highly dense (95.68%) and highly
conductive (0.26 mS·cm–1 at 25 °C) LLZTO
films are obtained through CO2 laser sintering. This work
provides a unique, scalable, and widely applicable ultrarapid laser
sintering technique to overcome the difficulties associated with classic
methods for the integration of SSEs for practical all-solid-state
Li-metal battery applications.