A battery is an electrochemical device that is used to power electrical devices, from simple household appliances to mobile phones, cars and aircraft.
Airbus/Rolls-Royce/Siemens E-Fan X demonstrator (cancelled) is an example of a programme looking to develop hybrid-electric aircraft powered by battery technology. On the other hand, VoloCity by Volocopter, EHang 216 and Lilium Jet are examples of electric vertical take-off and landing vehicles (eVTOLs) developed for Urban Air Mobility (UAM) where the propulsive power is delivered via batteries.
Batteries can be categorized in two ways - primary and secondary.
Primary batteries are designed to be exhaustive in their use, i.e. to be thrown away once the energy has been completely depleted. The chemical reactions within this battery are non-reversible hence they cannot be recharged.
Recharge allows for the reversal of chemical reactions via an electric current. Primary batteries lack this feature, so their applications are limited to disposable one-time use. Examples of such are the AA and AAA batteries used in household appliances and portable devices.
Secondary batteries on the other hand are rechargeable. The chemical reactions within this battery category are reversible with the application of an electric current.
This kind of battery can be used several times, recharged and discharged for thousands of cycles. Secondary batteries are used in rechargeable devices such as laptops, cars etc.
The oldest form of battery in existence is Lead-Acid, which is widely used in the automotive industry and on boats. eVTOLs are being designed to leverage the battery technology and are currently seen powered by Lithium-ion batteries.
Development in battery technology
Lithium-ion technology in the coming years is said to reach an energy limit. Although, discoveries of other disruptive active materials suggest that this energy limit can be overcome.
The next generation of Li-ion battery technology will allow for high levels of energy density that possess the ability to fine-tune performance features such as fast charge, temperature operating window (-50 degrees Celsius to 100 degrees Celsius). This fine-tuning can be achieved through the design choices of the cell and the chemistries involved within.
The Li-on batteries have other advantages such as very low discharge (a longer time taken for battery energy to be depleted), long life-time and thousands of discharging/charging cycles. Hence, they can be reused for a long period of time before needing to be completely replaced.
The applications of such batteries are intended for energy storage systems within the transportation sector (automotive, rail and aviation). This is where high energy density, power and safety within batteries is necessary.
Solid State Lithium batteries
Traditionally solid state batteries are known to offer stability (i.e. its composition is safe and no risk associated with its use). Where the battery can operate at super capacitor levels, it can achieve a complete charge or discharge in 7 minutes (this application is very useful for cars).
In comparison to current batteries, solid states are said to be far safer and provide increased stability. With continuous developments and research, the application of solid states can soon be seen in cars and future electric and hybrid-electric aerial vehicles. Hybrid configuration is currently suggested for usage within airliners for regional and long-distance travel.
Battery technology is used to power automotive vehicles such as those made by Tesla. On a single charge the Tesla Model 3 vehicle can travel a distance of 360 miles and with its supercharging capabilities can recharge 172 miles within 15 minutes.
Battery technology onboard eVTOLs enables a sustainable future of aerial transportation as part of the Advanced Aerial Mobility (AAM), including UAM to be delivered. While currently only short-distance travel is possible, in the future this could extend as far as regional missions and beyond, flown by various electrically-powered aircraft.
Sources and suggested reading :
Battery Technology - MIT Technology Review
5 New Battery Technologies That Will Change the Future - Gray
How Batteries Store and Release Energy: Explaining Basic Electrochemistry - Klaus Schmidt-Rohr