Non-toxic salt water battery prototype can charge in seconds

Date: Mar 22, 2019

A battery prototype has been designed using salt water and materials that are non-toxic and charge quickly, paving the way for new types of battery.

The design principles behind the new prototype, which changes colour as it charges, could also be applied to existing battery technologies to create new devices for energy storage, biological sensing, and smart colour-changing materials.

The most widely used batteries currently are lithium-ion batteries, which have a relatively high capacity (they hold a large amount of charge) but do not discharge or recharge their energy quickly. They also contain organic electrolytes and other materials that can be hazardous and flammable, meaning they require careful handling and disposal.

The new battery prototype, developed by a team of researchers from the departments of Physics and Chemistry at Imperial College London, uses thin films of specially designed plastics and simple salt water instead.

While it can hold less charge than conventional lithium-ion batteries, the prototype, which is made from polymers – long chains of molecules that make up plastics – can charge and discharge in a matter of seconds. As an added benefit of the materials it uses, it also changes colour as it charges, giving users an easy way to read out the state of charge of the battery.

The prototype, the details of which were published in Energy & Environmental Science, could pave the way for improving the charging rate and toxicity of existing batteries, or provide a route for making entirely new kinds of batteries.

Developing recyclable batteries

Co-lead author Dr. Alexander Giovannitti, who worked on the project while at the Departments of Physics and Chemistry at Imperial, said: “The materials we used to create the battery prototype could potentially be made at low cost and combined with the use of non-toxic and non-flammable water-based electrolytes. This approach could be a viable route to develop recyclable batteries.”

Batteries with faster charge time but lower capacity could have a range of applications where energy needs to be exchanged quickly but the batteries don’t need to be small, such as when energy from car braking is used moments later to accelerate the vehicle.

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