In a way, all batteries are nanotechnology: they exploit the behaviors of electrons in various anode and cathode materials to take on, store, and disperse electrical energy. Nanomaterials are materials with unique and interesting structures at the nanoscale, which are being exploited in the next generation of lithium-free batteries.
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Lithium-free batteries using different (and less rare) metals are on the rise. Many see them as a viable replacement for existing lithium-ion battery technology, which is criticized for its relatively low scale capacity for energy storage, problems with the global availability of lithium, relatively high costs, and various safety concerns.
Non-lithium batteries have been demonstrated with high energy density and good cost-effectiveness. This new generation of batteries is expected to develop significantly over the next few years and should be able to realistically compete with commercial lithium-ion batteries soon.
Metals such as zinc, magnesium, calcium, and aluminum have all been proposed as replacements for lithium.
Moving On from Lithium
The lithium-ion battery market has been and still is growing rapidly. Forecasters have predicted that the market will grow to $100 billion by 2025, up from just $30 billion in 2017.
Lithium-ion batteries are used almost exclusively in mobile phones, laptops, and numerous other consumer electronics. These products have become ubiquitous in the last few decades, spurring the rise of lithium-ion.
This rise is also attributable to the concurrent rise in battery electric vehicle sales and use, which nearly all use lithium-ion battery systems. However, increasing electrification across sectors, as well as growing energy storage and transportation needs from national electric grids and renewable power projects, also contribute to the rising demand for lithium.
However, lithium-ion batteries have several drawbacks that are likely to halt or slow this growth in the next few years. These are predominantly related to industrial applications requiring large-scale energy storage solutions.
Typically, lithium-based batteries come with a 40% higher production cost compared to alternatives, like nickel-metal hydride batteries.
Lithium-ion batteries’ discharge capacity tends to deteriorate faster than in batteries made with other metals. This is due to overheating, corrosion, and dendrite growth.
Related to these problems, lithium-ion batteries also pose serious health and safety concerns. In some cases, mobile phones or even electric car batteries have exploded without warning due to a build-up of gasses around the electrolyte.
Furthermore, lithium is a relatively rare material on Earth. Depleting lithium stocks in mines around the world is already contributing to a sharp price rise for the material, and this will only worsen as less lithium is available.
Because of these concerns, the search for lithium alternatives has been well underway in industry and academia for the last few decades.
Metals like zinc, magnesium, calcium, and aluminum have all been proposed and theoretically demonstrated as viable alternatives to lithium for batteries.
These materials are more abundant on Earth, and in the case of aluminum, for example, are much easier to recover and recycle from waste. They are also all used extensively in other industrial sectors. This means that they are not subject to the same price variations as lithium is, which in turn would reduce friction in the supply of energy storage worldwide.
Most of the proposed alternatives have a lower energy density than lithium. However, this means that they can typically operate at lower temperatures, which in turn will enable a longer working lifetime.
Nanomaterials Enabling the Next Generation of Lithium-Free Batteries
Advanced nanomaterials may hold the key for unlocking the battery application potential of these alternative metals on a commercially viable scale.
For example, potassium ion batteries have come under scrutiny due to the standard redox potential of potassium in aqueous electrolytes, which means that these batteries can maintain large cell voltages.
However, low electrical conductivity in potassium is a challenge. Novel electrolytes based on carbonite nanomaterials like carbon nanotubes, carbon nanofibers, carbon xerogel, carbon nanosprings, and carbon nanorods have been developed to overcome this issue.
Perhaps the most promising non-lithium battery technology that has been proposed so far is the non-aqueous metal-air battery technology. This technology could be especially beneficial in long-range electric vehicles, such as trucks and lorries for logistics.
These batteries use oxygen gas from their surrounding environment as a cathode material, alongside a metal ion.
Magnesium air batteries are safer, cheaper, and have a higher theoretical charge density than lithium-air batteries. Furthermore, magnesium is an abundant resource on the planet.
However, magnesium air batteries require unique and organic electrolytes with exceptional ionic conductivity and nanoscale magnesium anodes.
A composite nanomaterial of graphene and magnesium oxides has been proposed to create enough charge and discharge performance to make these kinds of lithium-free batteries possible.
References and Further Reading
Lithium ion batteries need to be greener and more ethical. (2021) [Online] Nature. Available at: https://www.nature.com/articles/d41586-021-01735-z
Manthiram, A. (2020). A reflection on lithium ion battery cathode chemistry. Nature Communications. https://doi.org/10.1038/s41467-020-15355-0.
Ponada, S. et al. (2022). Lithium-Free Batteries: Needs and Challenges. Energy Fuels. doi.org/10.1021/acs.energyfuels.2c00569.