Flow Batteries Are Here And They Will Change Everything
A new technology is taking battery sustainability to a whole new level.
As the world turns its back on fossil fuels, battery technology is becoming increasingly important. Unfortunately, our current batteries are far from ideal, particularly lithium-ion batteries. They have short lifespans, cost a bomb, have a substantial environmental impact, habitually catch on fire, and are difficult to recycle. But this is all set to change, as a new revolutionary battery is ready to take over. Welcome to the wonderful world of flow batteries.
Usually, when I talk about new battery technology, they tend to be concepts currently being developed in a lab, where they won’t see the light of day for years. But flow batteries are already a reality. Fort Carson, a US military base, has contracted Lockheed Martin to build a 10 MWh redox flow battery to store its solar farm’s energy. Why has this military base opted for this technology? Well, it has a nearly-infinite life cycle, almost no degradation, huge safety margins, is nearly 100% recyclable, is incredibly eco-friendly, and all while being astonishingly cheap.
The way that redox flow batteries achieve these incredible characteristics is down to their remarkably simple design.
Lithium-ion batteries store charge by moving lithium-ions from one side of the battery to the other. But the parts that hold this charge, the cathode and anode, execute the energy storage and power delivery. This dual-purpose means that we need complex chemistry in order to optimise the batteries. This complexity is why they are expensive and have such a huge carbon footprint and ecological impact, due to extensive mining. Moreover, this dual-purpose also leaves these batteries vulnerable to dendrites, the deposits that cause the battery to lose capacity over time. There is also the fact that lithium-ion batteries have an annoying tendency to catch fire, creating a new need for extensive safety measures to be put in place.
But redox flow batteries solve this by separating the parts holding the charge and the parts delivering the power. These batteries are made up of two tanks of electrolytic liquid with a “separator” in between and an electrode in each tank. When a current is passed between the electrodes, one electrolyte loses an electron (in a process known as oxidation) and gives it to the other (known as reduction). This means that one liquid is positive and one is negative, which provides an electrical potential, or voltage, between the two electrodes that can power a circuit.
To make this process more efficient, the tanks are made larger, and the electrolytic liquid is pumped into a ‘cell stack’ which holds the separator and electrodes. This creates a flow over the electrodes, which ensures the voltage stays constant and allows for a massive capacity, given the increase in electrolytic liquid.
So if you want a redox flow battery to hold more power, you can create larger tanks. Or, if you want it to deliver more power, you can create larger cell stacks. This flexibility means that it can effectively be tailored to its purpose, allowing it to be more compact and more efficient in order to best suit whatever job it does.