Researchers at Imperial College London developed a battery prototype using salt water and non-toxic materials that charges extremely fast.

The most widely used batteries currently are lithium-ion batteries, which hold a large amount of charge, but they do not discharge or recharge their energy quickly. They also contain materials that can be hazardous and flammable.

The current prototype consists of thin films of especially designed plastics and salt water. It can hold less charge than conventional lithium-ion batteries, but it can charge and discharge in a matter of seconds. Additionally, the battery changes colour as it charges, giving users an easy way to read out the state of charge.

Water-based batteries are desirable because they are non-toxic and non-flammable, but it has been difficult to get the ions in the water to be reversibly exchanged with the electrodes. The researchers got around this by designing side-chains to attach to the conducting polymer. By using polar materials for this, they were able to create electrodes with high affinity to water. This way, positive and negative electrodes can host their opposite ions from the water

The prototype could pave a way of improving the charging rate and toxicity of existing batteries, but also cover a new range of applications, like for storing solar or wind energy.

Photo: Imperial College London