A more sustainable alternative to lithium-ion batteries

Around the world, there is a rising demand for energy storage systems which lithium-ion batteries are unable to fulfil due to their use of critical raw materials. As the search for alternative battery technologies continues, a project called 4NiB, short for four-volt sodium-ion battery, has its sights set on this goal. The Centre for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW) has joined forces with three partners to develop sodium-ion batteries.

These batteries are a powerful, ecofriendly alternative. The project also aims to utilise bio-waste to productive use. The batteries will be tailored to suit urban electric vehicles and stationary battery storage systems. The German Federal Ministry of Education and Research (BMBF) is providing 1.35 million euros in funding over three years for this initiative.

Karlsruhe Institute of Technology’s (KIT) Helmholtz Institute Ulm (HIU), Forschungszentrum Jülich GmbH’s Institute of Energy and Climate Research and the University of Freiburg’s Materials Research Center (FMF) will join ZSW in the 4NIB.

Batteries are a key component of future sustainable energy scenarios, with demand for energy storage capacity forecast to grow from 700 GWh in 2022 to 4700 GWh in 2023. Vendors will not only have to produce enough batteries, but also draw on vast quantities of raw materials.

Sodium-ion batteries, which use sodium rather than lithium, are an emerging technology. Sodium is abundant and inexpensive, and can be extracted from sources such as sodium chloride or sea salt.

These batteries can be manufactured without using critical raw materials because their key components do not contain cobalt, nickel or lithium. Costs can be further lowered by avoiding copper foils current collectors. To make these batteries even more sustainable, they can be made with alternative carbon compounds sourced from renewables rather than the graphite currently used in lithium-ion batteries.

Sodium-ion batteries have already started rolling out in China; however, there is much to be done to improve this type of battery, so it will be a few years before it is mass-manufactured on an industrial scale.

The 4NiB project focuses on developing and coordinating anodes, cathodes and electrolytes to build a high-performance sodium-ion battery that is both cost-effective and ecofriendly. The project’s primary goal is to deliver a high performance cell in pouch format with specific energy greater than 200 watt-hours per kilogram.

The priority is to create high-voltage cathodes with four volts by developing polyanions-based mixed phosphates that are safe and remain at stable at high voltages. Researchers are using simulations to determine the right composition of transition metals to maximise stored energy. The anode is to be produced with hard carbon sourced from bio-waste, using feedstock products that are abundant in Germany.

A non-aqueous liquid will serve as the electrolyte. An added ionic liquid is to increase conductivity and safety. Researchers are also working on pre-charging strategies to maximise these batteries’ energy.

Image credit: ZSW.