The world’s smallest battery can power a computer the size of a speck of dust

The world's smallest battery can power a computer the size of a speck of dust

The world’s smallest battery is smaller than a grain of salt and can be produced in large quantities on a wafer surface. Credit: TU Chemnitz/Leibniz IFW Dresden

Computers are getting smaller and smaller, just as today’s mobile phones offer computing power similar to that of a laptop. And the trend towards miniaturization continues. Smart dust applications (small microelectronic devices), such as biocompatible sensor systems in the body, require computers and batteries smaller than a speck of dust. So far, this development has been hampered by two main factors: the lack of on-chip power sources for anytime, anywhere operation and the difficulties of producing embeddable microbatteries.

In the current issue of Advanced Energy Materials, Teacher. Dr. Oliver G. Schmidt, Director of the Chair for Material Systems of Nanoelectronics and Scientific Director of the Center for Materials, Architectures and Integration of Nanomembranes (MAIN) at the Chemnitz University of Technology, Dr. Minshen Zhu, who has been working in Professor Schmidt’s group at the MAIN research center since February 2022, and researchers from the Leibniz Institute for Solid State and Materials Research (IFW) Dresden and the Institute of Changchun Applied Chemistry presents a solution to these challenges. They discuss how battery-powered smart dust applications can be realized at the sub-millimeter scale and showcase the world’s smallest battery by far as an application-oriented prototype.

“Our results show encouraging energy storage performance at the sub-millimeter scale,” says Dr Minshen Zhu, and Professor Oliver Schmidt adds, “There is still enormous potential for optimization for this technology, and we can expect much more powerful microbatteries. in the future.”

Beyond the limits of miniaturization

The power needed to run tiny sub-millimetre scale computers can be provided by developing appropriate batteries or “harvesting” methods to generate electricity.

In the field of “harvesting”, micro-thermoelectric generators, for example, convert heat into electricity, but their power output is too low to drive chips the size of dust. Mechanical vibrations are another energy source for powering small-scale devices. Small photovoltaic cells that convert light into electrical energy on small chips also show promise.

However, light and vibration are not available at all times and places, making on-demand operation impossible in many environments. This is also the case, for example, in the human body, where tiny sensors and actuators require a continuous power supply. Powerful small batteries would solve this problem.

However, the production of tiny batteries is very different from their everyday counterparts. For example, compact high energy density batteries, eg button cells, are manufactured using wet chemistry. Electrode materials and additives (carbon materials and binders) are made into a slurry and coated on a metal foil. On-chip microbatteries produced using these standard technologies can provide good energy and power density, but have a footprint well in excess of one square millimeter.

Tesla technology rollback: Swiss-roll process enables on-chip batteries for dust-sized computers

Stacked thin films, electrode pillars or interdigital microelectrodes are used for on-chip battery fabrication. However, these designs often suffer from inferior energy storage, and the footprint of these batteries cannot be reduced significantly below one square millimeter. The goal of Prof. Schmidt, Dr. Zhu and members of their team was therefore to design a battery significantly smaller than one square millimeter in diameter and integrable on a chip, which still has a minimum energy density of 100 microwatt hours per centimeter. square.

To achieve this, the team wound current collectors and electrode strips on a microscopic scale, a similar process also used by Tesla on a large scale to make the batteries for its electric cars.

The researchers use the so-called “Swiss-roll” or “micro origami” process. A layered system with inherent tension is created by consecutively coating thin layers of polymeric, metallic, and dielectric materials onto a wafer surface. The mechanical tension is released by peeling off the thin layers which close automatically to roll up in a Swiss-Roll architecture. Thus, no external force is required to create such a self-coiled cylindrical micro-battery. The process is compatible with established chip fabrication technologies and capable of producing high throughput micro-batteries on a wafer surface.

Using this method, the research team has produced rechargeable microbatteries capable of powering the smallest computer chips in the world for about ten hours, for example to continuously measure the local ambient temperature. A small battery with great potential for future micro and nanoelectronic sensor and actuator technologies in areas such as the Internet of Things, miniaturized medical implants, microrobotic systems and ultra-flexible electronics.

Putting batteries on a chip could enable wearable sensors

More information:
Yang Li et al, On-chip batteries for dust-sized computers, Advanced Energy Materials (2022). DOI: 10.1002/aenm.202103641

Provided by Chemnitz University of Technology

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