Currently, the interest in flexible and thin electronic devices with a wide range of applications including mobile devices, healthcare, smart surfaces or wearables among others is growing. All of these applications require electrical power, so traditionally they have been connected to conventional batteries or grid power where appropriate. However, the characteristics of conventional batteries such as their limited mechanical flexibility (bulky, rigid and non-flexible) makes them unsuitable for powering flexible electronics.
The need for thin and flexible energy storage for electronic devices has driven industries to look for alternative solutions and sources. Energy harvesting techniques have increasingly been adopted for wireless devices to provide a self-sustaining energy supply. The environment provides infinite ambient energy, including piezoelectric, thermal, vibration, and photovoltaic energy. However, all energy harvesting systems need energy storage for times when the energy cannot be harvested. This energy storage device must have some specific characteristics such as a long-term lifetime (> 10 years), a long shelf- time (not limited) without performance changes, efficiency, and flexibility. Typically, the existing solutions based on batteries cannot offer all of these features, therefore, supercapacitors and thin film lithium-ion batteries have been developed as the best alternative for applications of energy harvesting.
Why is not thin film Li-ion battery the best solution? Despite of a lot of developments to improve thin film lithium-ion batteries and their advantages such as their high operating voltage (3.9V) and continuous current (1.25mA/cm2) moderate high discharge rate (0.3-8.2 oC), and low prices (€7-10); they still require more frequent recharge because of their minuscule size. For these reasons, the supercapacitors have surpassed thin film batteries for energy storage.
Supercapacitors are electronic devices that can store and deliver energy faster than conventional batteries. Among their special features are their ability to turn on instantaneously, charge quickly, and require less complicated charging circuits. Other important supercapacitor characteristics include high power densities andvery long lifetimes regardless of the number of charge cycles. These features make them very attractive for applications such as micro-energy harvesting applications, wireless telecommunications, etc. In comparison with electrostatic double-layer capacitors (EDLCs), thin film solid-state supercapacitors are more attractive as energy storage cells in the field of low power devices such as RFID tags, smart cards, internet of things (IoT), etc. For a wearable wireless device, the power sources life is crucial since some devices need to run on 24/7 such as medical devices (pacemaker or medical patches among others).
The final aim of Silent Energy Solutions is developing the world’s first commercial energy harvester, energy storage and power management in a single device. The ability to work and survive at high temperatures (-15 to +250 oC) gives our pseudocapacitor a unique ability to integrate it into materials such as polymers or elastomers, or deposite the device in material that suffer high temperature in the manufacturing process (vulcanization, etc.) such as rubber. This creates a market to develop ultra-low power systems for applications that were not previously possible such as tyres. We will be able to tailor and custom build the ultra-low power system to meet the client’s specific performance requirements.
