The work started from the premise that intelligent connected microsensors require miniature embedded energy sources with great energy density. For ultra thin or planar microbatteries, increased energy density means using thicker layers of materials. However, a second approach machines a silicon wafer to produce a 3D structure made of simple or double microtubes. According to the team, the 3D batteries retain a footprint of 1mm2, but have a specific area of 50mm2. These microtubes are said to be large enough to be coated with multiple layers of functional materials.
The main challenge was to deposit thin and regular layers on the complex 3D structures. Using Atomic Layer Deposition (ALD), the researchers created an insulating thin film, a current collector, a negative electrode, and a solid lithium phosphate electrolyte.
The next step will be to use ALD to develop thin films of positive electrode materials in order to create the first functional 3D prototypes.
The team comprised researchers from CNRS, Université de Lille, Université de Nantes and Argonne National Laboratory.
