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ion Synthesis of Solid Electrolyte (LixAlySizO) via ALD

Jane P. Chang, University of California-Los Angeles, DMR 0932761• Outcome: Researchers at UCLA have synthesized an ultra-thin ionic conductive film

via Atomic Layer Deposition (ALD) as an electrolyte in Li-ion microbatteries

• Impact: An ultra-thin film electrolyte (LixAlySizO) will provide unique opportunities in the development of a fully functional all-solid-state 3D Li-ion microbattery

• Explanation: Despite significant developments in electrode materials for potential 3D Li-ion microbattery, very little efforts have been devoted in developing a suitable solid electrolyte to enable a functional 3D Li-ion microbattery.

Prof. Chang’s group has successfully synthesized an ultra-thin electrolyte (LixAlySizO) that is conformal

over complex, high-aspect ratio structures with an excellent thickness control. This technology will enable an innovative miniaturizationsof the Li-ion batteries.

Current

Load

Li+

Li+

Li+

Li+

LixAlySizO

Anode

Cathode

1-2 mm

Proposed design of a 3D Li-ion micro-battery

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4k

3k

2k

1k

0

Intensity (A.U)

Ene

rgy

(eV

) Al K

O K

Si K

• A viable solid electrolyte material for 3D Li-ion microbattery applications needs to be conformal over complex 3D structures.

The conformality of LixAlySizO thin film deposited via Atomic Layer Deposition (ALD) over a high-aspect ratio (AR) Si trench (W: 0.6 μm, L: 6 μm, AR: 10) was studied by HRTEM. A conformal coating of LixAlySizO film was observed by EDX with Al Kα and O Kα emissions, confirming a successful ALD deposition.

(a) SEM and (TEM) of a high AR Si trench of a high AR Si trench showing a conformal coating of LixAlySizO along the sidewall of the trench (c) EDX spectra across LixAlySizO confirming the presence of the deposited film

Si Trench ALDFilm

0.6 μm

6 μ

m

Conformal Coating of Solid Electrolyte over Si TrenchesJane P. Chang, University of California- Los Angeles, DMR 0932761

EDX Line Scan

(a) (b)

(c)

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• An ultra thin film of LixAlySizO has been deposited via ALD over

a potential 3D anode material(a porous SiNW) to study the film conformality. HRTEM study of LixAlySizO coated porous SiNW (vs. bare porous SiNW) shows a conformal deposition over the entire nanowire while maintaining the porous morphology of the NW.

This HRTEM study demonstrated ALD’s superior thickness and composition control, which will likely play a key role in fabricating a well-tailored nanostructured electrode-electrolyte nanocomposite for 3D Li-ion microbatteries.

Conformal Coating of Solid Electrolyte over Porous SiNWJane P. Chang, University of California-Los Angeles, DMR 0932761

(a) (b)

HRTEM of (a) uncoated porous SiNW and (b) LixAlySizO coated porous SiNW. A conformal coating of LixAlySizO with a thickness of ~11nm has been observed over the entire wire, while maintaining the porous morphology of SiNW