Wednesday, October 12, 2016

ALD used in new 3D design for mobile microbatteries

Nanowerk News reports: In the race towards miniaturization, a French-US team-mostly involving researchers from the CNRS, Université de Lille, Université de Nantes and Argonne National Laboratory (US) as part of the Research Network on Electrochemical Energy Storage (RS2E)1-has succeeded in improving the energy density of a rechargeable battery without increasing its size (limited to a few square millimeters in mobile sensors).

Atomic Layer Deposition of Functional Layers for on Chip 3D Li-Ion All Solid State Microbattery

Manon Létiche, Etienne Eustache, Jeremy Freixas, Arnaud Demortière, Vincent De Andrade, Laurence Morgenroth, Pascal Tilmant, François Vaurette, David Troadec, Pascal Roussel, Thierry Brousse and Christophe Lethien
Advanced Energy Materials, Version of Record online: 11 OCT 2016

Supporting Information : LINK
 (Graphical abstract Advanced Energy Materials)
Nowadays, millimeter scale power sources are key devices for providing autonomy to smart, connected, and miniaturized sensors. However, until now, planar solid state microbatteries do not yet exhibit a sufficient surface energy density. In that context, architectured 3D microbatteries appear therefore to be a good solution to improve the material mass loading while keeping small the footprint area. Beside the design itself of the 3D microbaterry, one important technological barrier to address is the conformal deposition of thin films (lithiated or not) on 3D structures. For that purpose, atomic layer deposition (ALD) technology is a powerful technique that enables conformal coatings of thin film on complex substrate. An original, robust, and highly efficient 3D scaffold is proposed to significantly improve the geometrical surface of miniaturized 3D microbattery. Four functional layers composing the 3D lithium ion microbattery stacking has been successfully deposited on simple and double microtubes 3D templates. In depth synchrotron X-ray nanotomography and high angle annular dark field transmission electron microscope analyses are used to study the interface between each layer. For the first time, using ALD, anatase TiO2 negative electrode is coated on 3D tubes with Li3PO4 lithium phosphate as electrolyte, opening the way to all solid-state 3D microbatteries. The surface capacity is significantly increased by the proposed topology (high area enlargement factor – “thick” 3D layer), from 3.5 μA h cm−2 for a planar layer up to 0.37 mA h cm−2 for a 3D thin film (105 times higher).