Lithium is not the only option when it comes to battery storage. There are a wide range of technologies, which all vary considerably in terms of their cost, efficiency, suitability-of scale, and stage of development.
Sodium-ion Batteries
Sodium Batteries have become an emerging rival to Lithium-ion when it comes to large-scale energy storage. This is primarily due to the relative abundance of sodium resources, in comparison to lithium. This makes Sodium-ion batteries cheaper to produce, and less damaging to the environment.
They also have a lower risk of thermal runaway, and a high energy efficiency rate (more than 90%), however that efficiency is still lower than their Lithium-ion counterparts (95%-98%). Lithium-ion batteries also have a greater energy density, meaning that they can be more compact than Sodium-ion batteries, making the latter less suitable for smaller-scale storage.
Lithium-ion technology also has a head start in terms of infrastructure – manufacturing, recycling etc. – so Sodium-ion faces an uphill battle in being adopted beyond any specific large-scale applications.
Iron-Air Batteries
The use of common, non-toxic materials (Iron, Water, Air) means that Iron-Air batteries are much cheaper to manufacture than Lithium-ion, and have a less negative impact on the environment. The lack of flammable electrolytes also means that they are less prone to overheating, making them a safer option.
Due to this, there is great interest in the technology from the Electric Vehicle sector, where safety and low cost are key.
However, Iron-Air batteries are large and only have an efficiency of around 50%, lagging well behind both Lithium-ion and other forms of storage. The slow response time (how quickly power can be released when needed) is also a downside, and limits some of its applications.
Similar to Sodium-ion, Iron-Air appears best suited for larger-scale storage, over longer durations (where Lithium-ion batteries don’t perform as well).
Complimentary systems – where Iron-Air retains power for longer periods, whilst Lithium-ion batteries respond to short-term fluctuations in demand – offer some potential, though without a substantial improvement in their efficiency, Iron-Air is very much a supporting character, with limited use cases.
Flow Batteries
The unique storage method of flow batteries (where the power is stored as chemical energy within liquid electrolytes, rather than solid electrodes) allows them to last 3x-4x longer than solid-state batteries, which degrade much faster. They are safer and less toxic, and their response time also rivals that of Lithium-ion, which in theory makes them an ideal replacement for more regular-use applications.
Unfortunately, there are a number of disadvantages to flow batteries. As the battery is made up predominantly of fluid (which volume of which dictates the capacity of the battery) they can be large and extremely heavy. Therefore, they are far less portable, and their efficiency (around 80%) is middle of the pack, well behind Lithium-ion.
There are other forms of “battery” which are in the nascent stages of development, such as:
- Concrete Supercapacitors – Recent innovations indicate that standard concrete can be modified during production, to include conductive materials that enable energy storage. A carbon-cement supercapacitor could allow future buildings to also function as storage units (reducing the need for separate systems) and there are even suggestions that roads and pavements made from this same material could be used to power vehicles and streetlights (though the notion of creating a full-scale ‘Scalextric’ network is likely a long way from becoming a reality).
Further refinements will be required in terms of both energy efficiency and release, as well as the structural impact on the concrete material. - Thermal Storage – Simple materials such as salt, air, and bricks can be used to store energy in the form of heat, at a potentially lower cost than conventional batteries, whilst lasting much longer.
With a wide array of methods showing promise, it remains to be seen which ones are most viable, and at what scale these might operate.
Many of these alternatives appear quite promising, though so far none have displaced Lithium-ion as the preferred form of battery storage. In Part 4, we’ll review some alternative methods of energy storage to see whether any have the potential to surpass batteries in terms of efficiency, and sustainability.
