Lithium on the Grid

Energy needs have changed dramatically in recent decades. Today, many consumers want to be able to generate – and, crucially, to store – their own power, freeing them from reliance on the grid.

Lithium is a soft, highly reactive alkali metal with inherent nuclear instability; as a result, it does not occur freely in nature except in ionic compounds. High electro-positivity and low equivalent weight make lithium an ideal battery reactant, and the rechargeable lithium-ion battery was first developed in the 1970s. The three main basic components are the anode, cathode, and an electrolyte between them, which contains a dissolved lithium salt. By harnessing the chemistry of this electrolytic cell, the battery allows lithium ions to move from the negative to the positive electrode during discharge, and back when charging.[1]

In the 1980s, chemists explored how producing a long-life, low-cost rechargeable lithium-ion battery could be the key to the mass-production of electric cars,[2] and in 2006 researchers described how lithium-ion batteries might have the potential to corner the market for portable electronics.[3] Over a decade later, this tech is now in almost every pocket and is also being used on an industrial scale, generating new business for both battery manufacturers and chemical suppliers of electrolytes.[4],[5],[6] By 2022, the global market for lithium-ion batteries is predicted to be worth over $46 billion:[7] impressive returns for technology driven by basic chemistry.

Battery life: The Struggle is Real

Small, closed-system batteries have a life-cycle limit, beyond which they will no longer hold a charge, as well as a limit to how much energy they can hold in any one charge.[8] There has been research into the benefits of changing the anode material from carbon to silicon, which could deliver ten-times the storage capacity,[9] and into using innovative solid electrolytes rather than organic solvents. Developments in these fields have allowed lithium-ion batteries to move into a variety of commercial endeavors, including consumer electrics, medical devices, cordless industrial tools and plant, and a new generation of electric and hybrid vehicles.

Critically, the charge-cycle limit in a closed battery needs to match the expected lifespan of the product it powers, from a few years for mobile phones and handheld devices, to decades for electric cars. However, on a larger scale, individual lithium-ion cells in an industrial battery can be renewed and replaced. This has made it possible to begin to build super batteries to store vast quantities of electricity for the utilities market.[10] The key advantage of batteries over traditional grid storage is that they can absorb available power from any source – be it coal, solar, wind or nuclear – giving greater flexibility. They may also be better able to meet peak electricity demands than traditional plants.

The Future of Batteries

Commercial companies interested in energy storage are already testing these theories. In 2017, Tesla installed the world’s biggest lithium-ion battery in Australia in just 100 days – a facility with 100-megawatt capacity that was paired with a neighboring wind farm. The project is intended to curb the power blackouts caused by the enormous summer-time drain on the grid, while still pushing the agenda for renewable energy sources.[11] Over the battery’s first month of use, the power reserve generated 2.42 gigawatt-hours of energy and consumed 3.06 – a round-trip efficiency of approximately 80%.[12] Lithium-ion batteries can pack more energy into smaller and more lightweight units than other types of batteries, but they are not without drawbacks. Of note, safety concerns were raised when lithium-ion battery units on board airplanes began to smolder.[13] New technologies for the future are already being investigated.

One potential new blockbuster could be metal-air batteries,[14] which use a pure metal cathode and an air anode. These typically rely on resources much more abundant and less reactive than lithium, such as aluminum or salt-water. Metal-air batteries have a much higher theoretical energy density than lithium-ion batteries, but many practical challenges need to be overcome before we can declare them to be an electrochemical energy storage solution, and current research is looking at novel nano-catalysts.[15],[16] Energy, power, charge-discharge rate, cost, cycle life, safety, and environmental impact are just some of the factors that need to be considered when developing the next generation of batteries for various applications.9 ACS journals will continue to monitor with interest the rise of these chemical powerhouses.
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[1] How cells work. Available at: http://www.jmbatterysystems.com/technology/cells/how-cells-work [accessed 26/02/18].
[2] Chem Eng News 1980;58(29):5–7.
[3] Jacoby. Chem Eng News 2006;84(8):10.
[4] Bomgardner. Chem Eng News 2011;89(40):22–23.
[5] Voith. Chem Eng News 2010;88(26):12.
[6] Voith. Chem Eng News 2009;87(36):32–34.
[7] Lithium-Ion Battery Market Overview. https://www.alliedmarketresearch.com/lithium-ion-battery-market [accessed 26/02/18].
[8] Jacoby. Chem Eng News 2012;90(25):10.
[9] Jacoby. Chem Eng News 2009;87(13):8.
[10] Manthiram. ACS Cent Sci 2017;3(10):1063–1069.
[11] ARS Technica. Available at: https://arstechnica.com/cars/2017/12/tesla-beats-deadline-switches-on-gigantic-australian-battery-array/ [accessed 26/02/18].
[12] A month in, Tesla’s SA battery is surpassing expectations. https://theconversation.com/a-month-in-teslas-sa-battery-is-surpassing-expectations-89770 [accessed 26/02/18].
[13] Jacoby. Chem Eng News 2013;91(4):7.
[14] Li & Lu. ACS Energy Lett 2017;2(6):1370–1377.
[15] Chen et al. Nano Lett 2012;12(4):1946–1952.
[16] Hardin et al. J Phys Chem Lett 2013;4(8):1254–1259.

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