To the Nobel Prize... and beyond! The challenges of lithium batteries for a sustainable future12/11/2019
The largest salt desert in the world, the Salar de Uyuni in Bolivia, is home to the largest lithium reserve in the world. Credit: Wikimedia Commons.
DORY GASCUEÑA LÓPEZ | Tungsteno
John B. Goodenough, M. Stanley Whittingham and Akira Yoshino have been awarded the 2019 Nobel Prize in Chemistry for their contributions to the development of an energy storage technology fundamental to the mobile electronics revolution: lithium-ion batteries. Different lines of research are searching for the perfect combination of materials to optimize the storage capacity of these batteries, a key issue for the strengthening of electric transport. Among the most recent lines of research are the use of oxygen ions or the incorporation of silicon, a component already in use in some Tesla car models that could increase the storage capacity of this type of battery by up to 30%.
Chemical alternatives to boost capacity
Another proposal for an alternative chemistry is that of fluoride batteries, which have an energy density up to ten times higher than current lithium-ion batteries, according to Christopher Brooks, chief scientist at the Honda Research Institute and co-author of a recent study conducted in collaboration with Caltech and NASA. Other combinations to create high-capacity batteries —such as lithium-sulphur or lithium-air— are currently being explored.
One of the conditioning factors of lithium-ion batteries is that currently they need a full (and slow) charge to obtain a complete electrochemical reaction. According to the science journal Nature, a group of researchers from the Argonne Laboratory of the US Department of Energy has developed a technology that would reduce the charging time of batteries by exposing the cathode to a concentrated beam of light, such as white light from a xenon lamp.
In parallel, scientists at the University of Pennsylvania have suggested the possibility of charging an electric car in just 10 minutes thanks to asymmetric temperature modulation. This modification of the usual thermal parameters would make it possible to reduce the charging time and the exposure time of the battery to high temperatures, thereby also helping to increase its life span. Fully exploiting the battery’s life cycle is a key issue, as it is the first step towards boosting efficiency (much cleaner than the procedure for recycling them). Experts therefore suggest cascading the use of lithium-ion batteries through a hierarchy of applications to optimise the use of the materials they contain.
The new batteries incorporate materials such as silicon, oxygen ions or hydrogen to increase storage capacity and accelerate charging times. Credit: Audi.
Greener and easier to recycle
The amount of lithium available in nature is limited, so recycling within the context of the emergence and growth of the electric vehicle market is seen as necessary by the manufacturers themselves. A study also explains the indirect impact on other natural resources. The demand for water to process lithium is substantial: extracting one tonne of lithium requires 1,900 tonnes of water consumed by evaporation. In the Salar de Atacama (Chile), a major lithium production centre, 65% of the region's water is used for mining activities, forcing farmers to import water from other regions.
According to an analysis by the consultancy firm Creation Inn, the total amount of recycled lithium could reach 5,800 tons by 2025. More than 66% of lithium-ion batteries are expected to be recycled in China. Currently there are different methods that combine to achieve the most efficient recycling: the separation of physical materials, the recovery of hydrometallurgical metals, pyrometallurgical recovery or the recovery of biological metals, among others. Regulations in China make electric vehicle manufacturers responsible for the recovery of batteries, and require recycling channels and service points to collect, store and transfer old batteries to recycling companies.
A study published in Nature presents evidence that the battery recycling process is no less polluting (in terms of greenhouse gas emissions) than their production. Some of the solutions proposed to reverse this situation would involve rethinking the recycling process to make it more standardized and efficient. To this end, component classification and labelling technologies are fundamental, as well as the implementation of a design focused on recycling and more standardized by manufacturers. Robotics and artificial intelligence could hold the key to building a thorough and efficient recycling system thanks to sorting software.
Hydrogen batteries are positioned as one of the cleanest alternatives, but still have conditions such as the volume required by their tank. Credit: Ballard Power.
A future with hydrogen
If lithium fails to overcome these obstacles, science is already preparing an alternative to consolidate the transition to clean energy: hydrogen batteries. According to forecasts in the European Commission's HyWays project, hydrogen could reduce oil consumption in road transport by up to 40% by 2050. In addition, both electricity and hydrogen can be produced from any primary energy source, including biomass, wind or solar energy.
However, hydrogen also faces some technological challenges to be surmounted. A comparative analysis of electric batteries, hydrogen fuel cells and hybrid vehicles by scientists at Imperial College London has concluded that for hydrogen fuel cell electric vehicles (FCEVs), energy density is not the biggest problem, since chemical energy is converted into electrical energy in the fuel cell. The main obstacle would actually be the volume that the fuel tank would require. While it is clear that no option is free of technological obstacles on the path towards the real energy transition, batteries are undoubtedly the key to winning the battle against fossil fuels.
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