Better batteries build more sustainable electronics

By Marc Eichhorn   |   December 6, 2021

In One Digital Day, a book that Intel published in 1998 to celebrate its 30^th anniversary, a team of photographers was asked to capture the impact that the microprocessor was having on day-to-day life. In one of the resultant images, an American family has emptied their home of all its microprocessor-powered devices and arranged them on the front lawn. The effect is striking. The lawn is covered in large pieces of equipment: TVs, VCRs and desktop PCs; washing machines, food mixers, and dishwashers; games consoles, stereos, and more. They are mostly mains powered.

If you repeated this exercise today, the photographer would need to put a large punchbowl front and centre, to hold all the small, microprocessor-driven devices that have become part of our daily lives since then: think key fobs and garage-door openers, smart watches, smartphones and tablets, hearing aids and fitness bands, remote controls and Bluetooth earbuds, pet trackers, webcams and security sensors, stylii for tablets, and endless Internet of Things (IoT) devices.

Figure 1: iFixit’s teardown of the first Apple Pencil
revealed its rechargeable battery (Source: iFixit)

It’s a vivid demonstration of the way that electronic devices have become ever more prolific in our lives. Some things have remained the same, though: even though the devices may be smaller, they still need power to work. If one of the top parenting skills of the 1990s was being able to find D-cell batteries to power Tonka toys and play ovens on demand, in the 2020s it must be the ability to find CR2032 coin cells – or the right charging cable.

Legislators are working hard to manage the environmental impact of the resultant increase in the use of primary and rechargeable batteries, to ensure that they have a positive role in addressing climate change. It’s no use electrifying our transport system to reduce its carbon footprint if doing so causes a waste material problem that takes a lot of energy to solve, or worse, creates an infrastructure that is reliant on increasingly scarce specialist materials. And it’s no use us all getting fitness bands and improving our health if, at the same time, we are poisoning the planet with badly managed e-waste.

The European Commission wants to update EU legislation on batteries and battery waste materials, the Batteries Directive of 2006, to reflect changing socioeconomic conditions, technologies, markets and uses. Its proposals, published in December 2020, cover issues such as enabling competitive sustainability, boosting the circular economy, increasing recycling, and minimising the environmental impact of batteries.

Of course, one of the best ways of minimising the impact of battery use is to put the well-worn ‘reduce, reuse, repurpose and recycle’ strategy to work in our electronic products. In the 20-plus years since One Digital Day, the carbon footprint of many pieces of domestic and industrial equipment has already been reduced by using less material and energy to achieve the same, or better, functionality. The EU proposal also includes recommendations about repurposing, for example, saying that electric vehicle batteries should have a second life in grid storage farms. And it suggests new targets for the recycling of battery materials and complete batteries.

These macro-scale initiatives can only really be driven by governments and industries, but individual designers can contribute by shifting from using primary cells to using rechargeables – even in the smallest devices. The use of rechargeables should cut the total cost of ownership of a device by replacing the chore of changing primary cells for that of plugging in a charger. It should also make it possible to make the device more reliable by allowing it to be sealed apart from the charging port, or completely sealed if charged by induction.

While it is easy to source a rechargeable AA or AAA cell with good discharge characteristics and a high cycle count, it can be less obvious where to find small cells with similar characteristics that are the right size for integrating into earbuds, IoT devices and other small devices.

Nichicon has introduced the SLB series of small lithium-ion (Li-Ion) rechargeable batteries to serve this need. The parts offer a balance of high energy density and fast charge and discharge characteristics that is difficult to find in competing technologies, such as standard Li-Ion rechargeables or super-capacitors.

The SLB batteries have up to 50 times the energy density, suffer less leakage current, and can be discharged over longer periods of time, than super-capacitors. When compared with standard Li-Ion rechargeable batteries, the SLB cells can be charged and discharged more quickly and are safer. This combination of characteristics gives designers an attractive alternative to existing battery technologies or super-capacitors, which each can only offer one of these characteristics.

The SLB batteries are designed to support up to 20,000 charge/discharge cycles at 10°C and will continue to work down to –30℃. All this is achieved with high reliability and good safety characteristics. Nichicon says it has tested the SLB batteries by crushing them, piercing them, short-circuiting them, over-charging and rapidly discharging them, all without adverse effect.

The SLB batteries have also passed tests set by the United Nations to check that they are safe for exporting overseas.

Nichicon SLB series

These rechargeable cells can be substituted for wired power or primary cells in many current applications. However, their small size, high capacity, useful charge/discharge characteristics and good energy retention also create opportunities for designers to create new types of products.

For example, IoT ecosystems rely on distributing many Things into a wide variety of arbitrary environments. Many companies now produce small boards that carry multiple environmental sensors, capable of measuring characteristics such as temperature, humidity, air pressure, ambient light levels, and even air quality, in one unit. The boards are equipped with Bluetooth Low Energy (LE) connectivity so that they can become part of  a mesh network, over which they can report their environmental data.

This all adds up to an easy new way to track environmental data – until it's time to send someone out to find all the Things and change their batteries. Some manufacturers are addressing this issue by designing their boards for ultra-low power operation, so that they can be powered by a photovoltaic panel that charges a small secondary battery – such as the Nichicon SLB.

Other techniques for creating so-called ‘forever batteries’, which scavenge energy from the environment and store it in rechargeable batteries, are also becoming practical. There are systems that can scavenge energy from vibration, which are being used to power monitoring systems on rotating machinery such as large motors and generators.

There are also schemes for scavenging energy from radio signals. A company called Atmosic Technologies reckons that the combination of its very low power Bluetooth LE radio implementation and onboard energy-scavenging circuits, which accumulate energy from Bluetooth signals in rechargeable batteries, are enough to enable infrequent communications without the need for external power.

Intel’s 60^th anniversary is just seven years away now. If it re-ran its One Digital Day project in 2028 to mark the occasion, you can bet that once again there would be plenty of familiar objects – TVs, washing machines, games consoles – on that suburban front lawn. You could also make a safe bet that the number and diversity of small devices that had been gathered up for display would have increased dramatically. There would be many more personal health monitors, environmental sensors, portable screens, home security systems, wearables, and IoT nodes – all of them needing some source of power to serve their function.

Find out more about how Nichicon’s SLB range of high-performance Li-Ion small rechargeable cells can provide that power, or if you want to discuss your requirements with one of our FAEs, get in touch in your local language.

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About Author

Marc Eichhorn

Product Marketing Manager Batteries, Avnet Abacus...

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