Technology is increasingly mobile and that mobility is dependent upon our devices having power; power that comes from batteries.
By Graham Chastney, Principal Solution Architect
I just did a quick audit of the batteries in my life:
- Wireless keyboard
- Wireless mouse
- Weighing scales
- Car key-fob
- Bluetooth headset
- Emergency lighting
- House alarm backup
- Wall clock
- TV remote
- All of the other remote-controls
I’ve got a Logitech presenter remote for my laptop that has had the same battery in it for what must be 4 or 5 years now. The battery in my smartphone needs connecting to a source of power every few hours, one of those sources of power is a power-blocks that I carry in my work bag for fear of being left without power. I don’t have to think about the power in the presenter remote the same cannot be said of the battery in my smartphone.
Many of the batteries used are the ubiquitous AA and AAA formats that have been around since the early 1900’s. There’s also an AAAA and a ½AA standard, who knew?
Increasingly devices have embedded batteries, sometimes using standards sizes, sometimes utilizing specialist formats made specifically for the device.
As consumers we have three basic requirements for batteries:
- Long time between recharges, which generally means high-capacity
- Small and thin
But they aren’t the only requirements, we also want the battery to last for at least the lifetime of the device it’s embedded in and we don’t want the battery capacity to degrade over that lifetime.
Batteries work by chemical reaction between two compounds. We want the compounds in our batteries to be safe to use in day-to-day life without overheating and without adverse impacts to us or the environment.
We then want all of those requirements in a package that is cheap.
These requirements drive us to combinations of compounds that are a compromise. The current standard for rechargeable and embedded workloads are Lithium-ion (Li-ion) batteries but even they aren’t perfect and have some serious safety issues including thermal runaway. Thermal runaway is what happens when the integrity of the materials inside a battery are compromised causing an internal short-circuit and the associated heat build-up, just ask Boeing about their experience with the 787 Dreamliner.
My son had an iPhone that experienced a thermal runaway event while it was in his pocket, on a London Tube, this eventually left the interior of the phone as a melted charred mess.
Whilst Lithium-ion batteries are great workhorses the current generation of batteries are also frustratingly short on capacity, or perhaps more correctly, frustrating short on size. Each of the device vendors is making a compromise decision between the overall size of the device and the internal capacity left for a battery. One of the benchmarks, as an example, for each new generation of iPhone is its thickness. The thickness of the iPhone is a design parameter for Apple and they like to declare that each iPhone is thinner than the last. That thinness comes at the cost of batteries that really don’t last a full day and a massive market in power-packs and cases that include the extra power that we need. Samsung made battery capacity part of its advertising campaign for the Samsung Galaxy S5 making a point of highlighting that the battery in the S5 was interchangeable, only to make the battery in the S6 embedded.
In the technology world we are used to raw performance doubling every 12 to 18 months under Moore’s law, that’s our expectation, but it’s not been true for battery technology. The Lithium-ion battery has been a work-horse for nearly 25 years now, in that time there have been a number of incremental improvements in capacity, but nothing approaching Moore’s law. In many ways Moore’s law makes the lack of progress in battery technology even more striking as the devices that we carry around get increasingly powerful leading to higher power expectations.
The lack of significant changes in the commercial battery market doesn’t mean that there isn’t lots of research being undertaken and novel approaches being investigated; one area being researched are 3-D battery technologies. Most of today’s batteries are built from 2-dimensional layers of polymers giving us the flat batteries that we carry around in our devices today. One of the major factors in the capacity and power output of any battery is the surface area between the two compounds used. Moving to a 3-dimensional architecture allows that surface area to be increased resulting in an increase in both power and energy density. A start-up called Prieto recently demonstrated a 3-D battery that utilized a foam structure resulting in thin, flexible batteries that have the potential to store more than current Lithium-ion batteries. Others are working on utilizing novel materials in batteries, such as graphene and its unique properties.
I’ve mostly talked about batteries at the small and mobile end of the requirements, but the use of renewable energy generation and other changes in the way we use and generate power are creating requirements to store huge amounts of power. Renewable energy is normally creating energy at a time when we don’t need it, so the energy it creates needs to be stored until we do need it. Whilst the technology approaches already described have the potential to contribute to resolving these challenges there’s also a different set of technologies being investigated for these use cases. One such approach is the use of molten salt as a mechanism to store energy as heat from which energy is extracted by using standard heat pumps.
Power is still the unsolved problem for our mobile world, but there are lots of interesting things happening – unfortunately it looks like we are going to have to wait a little longer for them.
Graham Chastney is a Technologist in CSC’s Global Infrastructure Services. He has worked in the arena of workplace technology for over 25 years, starting as a sysprog supporting IBM DISOSS and DEC All-in-1. Latterly Graham has been working with CSC’s customers to help them understand how they exploit the changing world of workplace technology. Graham lives with his family in the United Kingdom.