I read an article a day or so ago, mostly about the development of a new type of battery in China, which it was said could give your average electric vehicle (EV) a range of about 1,000 kilometres1.
While the stated range on EVs are based on optimum speed and conditions, real-world usage rarely allows the vehicle to come close to the stated range. For instance, our Hyundai Kona EV is stated to have a range of about 440 km, whereas, on one trip we did, we charged it up to a recommended 90% on a fast charger at Pheasant’s Nest while we had lunch (90% is recommended because charging from 90% to 100% takes a relatively long time). By the time we reached our destination after 225 km of mostly 110km/h highway driving, we were down to 20% charge. So, at a rough guess, I’d expect a range of about 250 km is more accurate (i.e. about 57% of the claimed range). The reason this differs so much from the stated range is because of the highway speed at which you need to travel (i.e. 110 km/h) to avoid being a major impediment to other vehicles, and because there was a lot of traffic, including many trucks, which entailed much deceleration and acceleration.
So, a claimed range of 1,000 km would, under highway driving conditions like those above, give you a range of about 570 km, which is still very impressive, and would easily get you from Sydney to Canberra without a recharge along the way.
The Kona uses lithium-ion NMC (which stands for Nickel Manganese Cobalt) batteries. It’s the most common sort of battery chemistry and is used in millions of electric cars around the world. This battery technology has been in use for nearly 15 years. It is recommended that you only charge it to 80% for routine use if you don’t need the full range. That helps to keep the battery in good condition for as long as possible2.
Lithium-ion batteries use lithium ions to create an electrical potential (i.e. voltage) between the anode and cathode terminals. A thin layer of insulating material called a “separator” sits in the electrolyte solution between the two sides of the battery. The separator allows the lithium ions to pass through while blocking the electrons and keeping the two electrodes apart. During charging, lithium ions move through the separator from the positive side to the negative. While discharging, the ions move in the opposite direction. The movement of the lithium ions creates an electrical potential difference. The electrolyte that separates the two terminals in the battery generally contains lithium salts in an organic solution which is flammable3.
Unlike conventional lithium-ion batteries, the new battery developed in China is a solid-state battery which does not rely on flammable liquid electrolytes. Solid-state batteries use a solid material to move electrical charge between electrodes.
This difference not only removes the risk of leakage or fire but also enables the use of pure lithium metal (as opposed to lithium salts) that, in a battery, can store two to three times more energy than in the standard lithium ion types. However, solid-state batteries have long faced a persistent problem. Their rigid layers tend to separate over time as the layers expand and contract during charging, which decreases the effectiveness of the battery and shortens its life. To try to overcome this problem, traditional solid-state battery designs require roughly 50 atmospheres (~5 megapascals) of external pressure to stay stable4.
To overcome this major problem, the researchers introduced iodine ions into the solid electrolyte. When the battery operates, these ions migrate toward the interface between the electrode and the electrolyte, forming a thin iodine-rich layer. This layer actively attracts lithium ions and automatically fills the microscopic cracks and pores that develop with use. The result is a self-healing interface that keeps the layers tightly connected without any external pressure. This has been a major step in overcoming the problem that has hindered the practical application of solid-state batteries. Testing of these prototype self-healing batteries showed they maintained steady performance after hundreds of charge and discharge cycles4.
If scaled successfully, the technology could revolutionise energy storage across multiple industries. Higher energy density means that smartphones could run for days between charges, rather than the current one or two days, and electric vehicles and aircraft could travel two to three times farther than current models on a single charge. This technology is in the early stages and large-scale batteries capable of handling thousands of charging cycles will require more testing and refinement4.
The future is coming, and most of it seems to be coming from China.
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