Tuesday, March 29, 2016

Atomic/Molecular Layer Deposition of Lithium Terephthalate for Li-Ion Battery Anodes

EurekAlert.org reports: When microbatteries are manufatured, the key challenge is to make them able to store large amounts of energy in a small space. One way to improve the energy density is to manufacure the batteries based on three-dimensional microstructured architectures. This may increase the effective surface inside a battery- even dozens of times. However, the production of materials fit for these has proven to be very difficult.


Aalto University Researchers testing the material on coin cells. (Mikko Raskinen / Aalto University)

Researches at Aalto University, Helsinki Finland, has develooped a ALD/MLD deposition process for Li-terephthalate, which has been published in Nanoo Letters (below).

- ALD is a great method for making battery materials fit for 3D microstructured architectures. Our method shows it is possible to even produce organic electrode materials by using ALD, which increases the opportunities to manufacture efficient microbatteries, says doctoral candidate Mikko Nisula from Aalto University. (EurekAlert.org)

Atomic/Molecular Layer Deposition of Lithium Terephthalate Thin Films as High Rate Capability Li-Ion Battery Anodes

Nano Lett., 2016, 16 (2), pp 1276–1281




We demonstrate the fabrication of high-quality electrochemically active organic lithium electrode thin films by the currently strongly emerging combined atomic/molecular layer deposition (ALD/MLD) technique using lithium terephthalate, a recently found anode material for lithium-ion battery (LIB), as a proof-of-the-concept material. Our deposition process for Li-terephthalate is shown to well comply with the basic principles of ALD-type growth including the sequential self-saturated surface reactions, a necessity when aiming at micro-LIB devices with three-dimensional architectures. The as-deposited films are found crystalline across the deposition temperature range of 200–280 °C, which is a trait highly desired for an electrode material but rather unusual for hybrid inorganic–organic thin films. Excellent rate capability is ascertained for the Li-terephthalate films with no conductive additives required. The electrode performance can be further enhanced by depositing a thin protective LiPON solid-state electrolyte layer on top of Li-terephthalate; this yields highly stable structures with capacity retention of over 97% after 200 charge/discharge cycles at 3.2 C.