Atomic layer deposition of inorganic electrolytes for lithium-ion batteries

The first generation of Li-ion batteries was mainly based on LiCoO2 and graphite. To achieve better
performing batteries, promising high-voltage (e.g. LMNO) and high-capacity (e.g. Si) electrode
materials have been developed in the past decade. Key issues for implementing these novel
materials in batteries are related to the interface between the solid electrode surface and the
liquid electrolyte that is present in the battery. Solvent oxidation, reduction and metal dissolution
and redeposition are caused by the direct electronic contact between the electrode surface and
the liquid electrolyte.
In this project we aim to resolve these issues by overcoating the electrode surface with a thin
protective coating of a solid electrolyte, i.e. a nanocoating that is blocking the transport of
electrons but that is conducting Li ions. The coating will be deposited using Atomic Layer
Deposition (ALD), which is ideally (and arguably uniquely) suited for the conformal deposition of
nanocoatings onto the complex porous 3D surface of a battery electrode.
We aim at developing novel ALD processes for the deposition of amorphous oxides and oxynitrides
with an ionic conductivity better than 10e-7 S/cm and an electronic conductivity below 10e-12
S/cm. The performance of the developed solid electrolyte coatings will be validated in three types
of demonstrator cells, where we aim to improve the cyclability and the rate capability
(charge/discharge kinetics) of next generation electrode materials.