Time and time again researchers and the media report on “game changing” technologies that appear to defy the laws of physics, and the so called “massless battery” is one of them. What challenges do battery technologies present, what are massless batteries, and why are they anything but?

What challenges do battery technologies face?

The importance of battery technologies cannot be understated; they are responsible for powering the vast majority of portable devices including smart watches, smart phones, IoT sensors, and handheld tools. They are also critical in numerous transportation technologies including cars, trains, planes, and boats whether it is to provide current for a starter motor or as the sole source of energy.

Considering that batteries are used to provide an energy source, it is blindingly obvious that the most important feature of all batteries is that they have sufficient storage capacity. This is why researchers tirelessly look for new compounds and structures that can increase the energy density of modern batteries. 

Increasing the energy density of a battery also allows for the size of the battery to be reduced while still maintaining the same energy capacity. As such, higher energy densities also lead to smaller and lighter batteries, and this weight reduction not only has a significant impact on handheld devices, but also helps to increase the range of EVs.

However, increasing the energy density is easier said than done, and researchers have to be extremely careful when doing so. If a battery has its energy density increased while retaining its size and mass, the amount of stored energy will undoubtedly increase. Therefore, any failure in the device (such as a short circuit) will see more energy dissipated. In the case of lithium-ion batteries, this failure can be catastrophic with fires that are virtually impossible to put out.

In order to make such batteries safer, manufacturers will use thicker battery cases to prevent punctures and bends. However, the use of such cases will increase the mass of the battery, and may even nullify the gains made in the increase in energy density. 

Thus, researchers are constantly trying to find methods for balancing energy density with structural integrity and cost. 

What are “massless batteries”

Recently, there has been media attention surrounding the development of “massless batteries” with numerous reports suggesting that they will revolutionise the battery industry. Simply put, massless batteries are those that do not use a separate battery enclosure to house the active components (i.e. electrolyte and electrodes), and instead take advantage of the enclosure of the device using the battery. For example, a massless battery used in a smartphone would not have a separate battery inserted into the device, but instead integrate the battery directly into the shell of the case. By using the phone case as the battery shell the weight of the battery is significantly reduced.

This technology has been demonstrated by the Chalmers University of Technology on a small scale with a stamp-sized battery providing power to an LED. The video demonstration then shows mechanical stress being applied to the battery with the LED remaining on. Currently, the battery demonstrated by the researchers has an energy density of 24Wh which is 20% of current lithium-ion batteries, and the batty has a mechanical stiffness of 25GPa which the researchers said was on par with numerous construction materials.

Why are massless batteries anything but?

While it may seem like a revolutionary technology, there are numerous issues behind the concept of massless batteries. At the same time, numerous media sites have failed to do any due diligence in their reporting and worse, the initial report on the research from the university itself has referred to their technology as “massless”.

To start, the fact that the energy density of the new technology is lower than lithium-ion automatically indicates that such a battery would be heavier. If the energy density of lithium-ion doesn't take into account for the battery casing, the same applies to the so called massless battery. Even if there is a mass reduction from integrating the battery into the structure of a product, the weight saving would be marginal for portable devices.

It is possible that integrating the new battery into the structural components of an EV could yield a lower weight and thus increase the range, but this introduces its own serious of issues. As EVs require enormous amounts of energy to operate, the capacity of a so called “massless battery” would still need to be large. 

Therefore, any damage to structural parts will generate a short circuit, and this could see catastrophic failure of the battery (causing fires). Considering that vehicles often experience dents and bumps, this introduces the risk of a failure should someone knock the side of the car with a shopping trolley.

Current lithium-ion technologies already have the capability of being integrated into the enclosure of a device, but there are good reasons why this is not done. Calling this new technology “massless” is dangerous as it spreads misinformation on current battery technologies and is also a lie as the battery still has mass. 

Overall, the only thing this battery demonstrates is how desperate researchers can be when announcing new technologies, and how the media rarely checks what they print. Maybe the media should stick to what they are good at which at this rates seems to be celebrity gossip and misleading adverts.