Scientists are looking for a series of solutions to replace lithium batteries

The world is racing to find alternatives to lithium-ion batteries, anticipating the prospect that the demand for this type of battery will increase 60 times in just 2 decades.

The use of elements such as lithium, cobalt and nickel to make batteries has exposed the world's dependence on scarce and expensive toxic materials. Meanwhile, their exploitation and processing also causes many environmental problems. It takes two million liters of water to extract 1,000kg of lithium.

Therefore, researchers are urgently searching for alternative materials that are in abundant supply, renewable, biodegradable, safe, low cost and have little impact on the environment. According to European Union forecasts, a solution may be near, with sodium and calcium - two abundant elements being studied to prepare for the prospect of a 60-fold increase in lithium demand in two decades.

Currently, there are two major challenges that society faces: electrifying vehicles and storing renewable energy to provide continuous electricity.

John Abou-Rjeily, a researcher at Tiamat Energy, part of the French National Center for Scientific Research (CNRS), which develops and produces sodium feedstock, said: 'There are not enough lithium, cobalt and nickel ion batteries. to meet everyone's needs'.

This doctor of materials physics and chemistry is studying the possibilities of sodium - one of the most common chemical elements in the Earth's crust, which is also a safer and cheaper material than lithium.

A Volkswagen employee conducts battery testing at an electric car battery manufacturing facility, on May 18, 2022 in Salzgitter, Germany. (Photo: Getty Images).

However, sodium-based materials require more space , which is why sodium-based batteries are not yet suitable for very small devices. They also cannot compete with current fuel storage systems that power electric cars, but could serve as an alternative on short routes. Mr Abou-Rjeily explains: 'While I have never challenged the 500km range of a lithium-ion battery, this sodium-ion battery could be more competitive for short and medium distance electric vehicles '.

Scientists say that a change in perception will further promote the adoption of sodium as an alternative, as it will allow this technology to be deployed right at home and in the workplace as a system. energy storage system from renewable sources. This is the goal pursued by Magdalena Graczyk-Zajac, a visiting professor at the Technical University of Darmstadt in Germany, and a member of the European SIMBA project, an EU-funded initiative aimed at developing sodium-ion battery for the home and will finish the first phase of research in June.

Researcher Graczyk-Zajac is committed to finding a way to store the energy captured by home photovoltaic panels in rechargeable sodium ion household batteries. This method would power homes and charge residents' electric vehicles at a significant cost reduction. 'You can drive your car for free [energy] for eight to nine months of the year,' she said .

Currently, a prototype has been tested in the laboratory. Part of the battery, the anode, is made from hard carbon, which can be produced from wood or biological waste. The remaining part, the cathode, can be made of a material called 'Prussian white' (PW) - a chemical compound rich in sodium, one of the most common metallic elements.

Sodium-ion battery. (Photo: Energysource).

Spain's CIC energiGUNE research center is making its own development in this field, they have created a sodium metal anode with a thickness of only 7 microns (70 times thinner than current anodes) thanks to the application using physical evaporation process. According to CIC energiGUNE, this advance opens the door to the production of flexible solid-state batteries with thin sodium anodes, a safer, cheaper and more compact alternative to current batteries with liquid electrolytes. Use graphite.

Montse Galcerán, lead researcher on the project, explains: ' Sodium cannot be easily laminated due to its sticky texture, similar to plastic. By far the most common method used to roll a block of sodium is as basic as handling it with a hammer, but this means that it is impossible to obtain a thin and uniform sheet, and therefore, there is a large amounts of unused sodium in the battery. But thanks to the evaporation method, we have overcome that obstacle.'

This thinning of the anode allowed researchers to reduce the amount of sodium needed as well as reduce the cost, weight and size of the battery, while increasing energy density (larger storage capacity) and safety. .

Another element used in place of lithium is calcium . 'It is one of the most abundant elements in the Earth's crust and it is not concentrated in specific geographical areas like lithium' , said Rosa Palacín, from the Barcelona Institute of Materials Sciences (ICMAB-CSIC) and is a member of the CARBAT project, said, adding that if raw materials are cheap, batteries can also be cheap.

Using calcium as the negative electrode offers an advantage over graphite in lithium-ion batteries because it is capable of accumulating greater energy density per kilogram than conventional lithium batteries. This type of battery also forms small hard structures called dendrites and can short circuit or explode after repeated use.

'When calcium passes through the electrolyte, two electrons flow out, instead of one as in the case of lithium. It can be assumed that a battery of the same size will offer greater autonomy if used in an electric vehicle, as long as a suitable positive electrode is found' , explains Ms. Palacín.

Other researchers from the Technical University of Denmark are also looking for a battery made from an aluminum anode and a sulfur cathode. Aluminum is even more abundant than calcium, but incorporating it into batteries presents similar difficulties.

'All the materials used are cheap. Aluminum, sulfur, electrolyte and urea are very cheap. Even polymers are the same ,' says researcher Juan Lastra, who defends the use of this method for energy storage from wind or solar parks.