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Porous germanium-based anode-on-chip architecture for high-performance energy storage microdevices



With an ever-increasing number of electrically powered products, the growing demand for performance and battery life is forcing manufacturers to increase the lifespan and storage capacity of their batteries. If the cathode (the one that supplies the energy) limits the capacity, the anode (the one that stores the energy) limits the performance and the life of the battery. Current power supply systems are far from optimal. With the development of the cathode with higher capacities, the anode, which is generally based on graphite, became obsolete (specific capacity of 372 mAh/g).

The most prominent candidates to replace graphite are the group IV semiconductors, namely silicon (Si) and germanium (Ge). Si has a very large theoretical capacity (4200 mAh/g) but also a large volume expansion during lithiation (400%). Ge, although having a lower specific capacity (1600 mAh/g), has a lower volume expansion (150%) and other properties: a better diffusion coefficient of lithium-ion, a higher lithiation potential low and higher electron mobility - properties for applying different storage regimes (from battery to supercapacitor). Thus, Ge is a very promising candidate to allow future batteries to reach unparalleled levels of performance.


The development team behind this invention is a world leader in the electrochemical etching of germanium. The invention describes an anode-on-chip architecture for energy storage, a unique approach that differs from slurry-based electrode fabrication processes. It consists of a single electrode made of a nano-structured Ge (with or without carbon-based functionalization) and its substrate, corresponding, respectively, to the active material (which stores the energy) and to its current collector which allows the transport of electrons to the active material.

The nano-structuring of an electrode makes it possible to minimize the mechanical stresses during the volume expansion generated by the lithiation process, and to increase its lifetime. There are currently different methods to achieve this, but the simplest and most transferable to industry, electrochemical etching, was developed at the University of Sherbrooke. The porous electrode-on-chip based on Ge is a technology with great potential, both for lithium batteries, but also for sodium, lithium-sulphur, potassium or hydrogen batteries. Besides the advantage of the material, the on-chip architecture makes it possible to maintain perfect electrical contact between the active material and the current collector, ie the porous layer and the substrate. This contact makes it possible to apply different discharge currents, thus making it possible to reach regimes with high energy density, but also with high power density. This duality of performance, between materials and architecture, allows a versatile application in energy storage. The one-step method eliminates the manufacturing steps usually used for powder electrodes. Moreover, this anode architecture is without binder or solvent, and thanks to the perfect electrical contact between the active material and the current collector, no conductive additive is necessary. Thus, its integration into production lines is facilitated, making this architecture an ideal candidate for solid-state batteries and micro-batteries, and more generally for all systems developed within the framework of the Internet of Things (IoT).



  • On-chip anode method:

  • Ability to embed the porous Ge directly onto the cell substrate, greatly reducing the number of steps required.

  • Unique architecture using the substrate as a current collector, which limits the number of manufacturing steps and allows easy integration on a wafer, thus providing perfect electrical contact with the active material.

  • Electrode with higher power and energy density than conventional storage systems.

  • Can be used with liquid, viscous and solid electrolyte.

  • Easy to implement in lithium batteries - life of these anodes could be extended for high flow and high energy applications.

  • Architecture without binder and without solvent; no conductive additives are needed.


  • One-step anode manufacturing process.

  • Easy to mass produce.

  • Low-cost nano-structuring methods already standard in the industry:

  • Electrochemical and chemical etching - easily integrated into production lines.

  • Chemical Vapor Deposition (CVD)

  • Ge provides a surface for the growth of carbon and graphene by CVD. As with nano-patterning, the use of CVD to functionalize the surface with carbon, and thus limit the SEI, has mainly been demonstrated and is beginning to be used in industry.


  • Lithium ion batteries

    • Market - US$94.4 billion by 2025.

  • Micro-batteries - developed to allow miniature systems to be electrically powered.

    • Market - $842 million by 2026 - powering Internet of Things (IoT) devices.

    • IoT Market to Hit $1.85 Trillion in 2028 - Smart Mobile Phones, Connected Cars, Smart Bikes, Medical Sensors, Fitness Trackers, and More

    • Applications of micro-batteries:

    • Wearable - cell phone earbuds, fitness equipment, medical - hearing aids, insulin pumps, etc.

    • IoT - connected sensors, automotive - "smart keys", automated toll systems.

    • Robotics, cordless tools, alarm systems, etc.

  • Solid state batteries

    • Market - $314M by 2028.

  • Supercapacitors, pseudo-capacitors.



TRL 6 - for the anode

  • - Ready for transfer to industry.

  • o Demonstration of a lithium-ion micro-battery using a metallic lithium cathode, a liquid electrolyte and a CR2032 button cell. Best battery performance obtained with a columnar morphology. Once the germanium has been porosified and cleaved, the sample is directly placed in the button cell and used as a negative electrode.


  • Patent pending in the United States.


Development partners. Investments. Licenses. Commercial Partners

Project Director: François Nadeau

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