As the world shifts towards renewable energy, moving on from fossil fuels, but at the same time relying on ever more energy-gobbling devices, there is a fast-growing need for larger high-performance batteries. Lithium-ion batteries (LIBs) power most of our portable electronics, but they are flammable and can even explode, as it happened to a recent model of smartphone. To prevent such accidents, the current solution is to encapsulate the anode – which is the negative (-) electrode of the battery, opposite to the cathode (+) – into a graphite frame, thus insulating the lithium ions. However, such casing is limited to a small scale to avoid physical collapse, therefore restraining the capacity – the amount of energy you can store – of the battery.
Looking for better materials, silicon offers great advantages over carbon graphite for lithium batteries in terms of capacity. Six atoms of carbon are required to bind a single atom of lithium, but an atom of silicon can bind four atoms of lithium at the same time, multiplying the battery capacity by more than 10-fold. However, being able to capture that many lithium ions means that the volume of the anode swells by 300% to 400%, leading to fracturing and loss of structural integrity. To overcome this issue, OIST researchers have now reported in Advanced Science the design of an anode built on nanostructured layers of silicon – not unlike a multi-layered cake – to preserve the advantages of silicon while preventing physical collapse.
This new battery is also aiming to improve power, which is the ability to charge and deliver energy over time.