EV battery with power up to 1 million kilometers

 'Single crystal' electrodes could power cars for up to 1 million of kilometres

New single-crystal battery design may allow EVs to last 1 million km's while reducing waste and environmental damage. Single crystal electrodes in lithium-ion electric vehicle batteries enable them to last several times longer than existing technology. A lithium-ion battery with a single crystal electrode has been continuously charging and discharging for 6 years while retaining most of its energy storage capacity. New research shows, batteries with "single-crystal electrodes" could power electric vehicles (EVs) for millions of km's, meaning their batteries would outlast other parts of the cars and allow electric vehicles to drive a million km's before replacement, easing costs and cutting waste. Electric vehicles are redefining transportation, but battery lifespan remains a key hurdle. Lithium-ion batteries, the backbone of most EVs, degrade over time. This leads to costly replacements and growing environmental concerns. But a new breakthrough in battery design might pave the way for batteries which last up to one million km's without needing to be swapped out.

A lithium-ion battery with this new type of electrode has been charging and discharging constantly for six years, retaining nearly 80% of its original capacity. Battery cycled eight times longer than a regular lithium-ion battery, equivalent to an electric car driving 5 million miles (8 million km's), researchers reported. The heart of the problem lies in how these batteries charge and discharge. Inside, nickel-based cathode materials store lithium ions. These materials are made of many tiny crystals. Over time, repeated charging and discharging causes the crystals to break apart. This weakens the structure and reduces the battery’s ability to hold a charge. Researchers have been looking for ways to extend battery life. One promising solution involves reshaping how these nickel cathodes are made. Instead of using many small crystals, scientists explored forming the material as a single large crystal. Unlike their multi-crystal counterparts, single-crystal materials are more resistant to damage, potentially offering a longer-lasting solution for EV batteries. To understand what makes these crystals more durable, researchers at Pohang University of Science & Technology in South Korea studied how temperature affects their structure. Led by Kyu-Young Park, the team tested various heat levels to identify the point where high-quality single crystals could form. They found that at temperatures above 850 °C, the internal structure of the cathode undergoes a major shift. Tiny grains within the material fuse and grow, while air pockets between them vanish. This process, known as densification, creates a hardened structure which resists wear and tear.

All batteries slowly wear out and lose some of their energy-storage capacity over time. For instance, your phone battery holds less of a charge after a few years than it did the day you bought it. The same is true of electric car batteries: When their storage capacity drops, so does the distance the car can travel on a single charge. However, when polycrystalline materials are made at high temperature, they become too dense. With fewer pores to absorb stress, they’re more likely to crack during use. In contrast, single-crystal cathodes formed at the same temperature hold up better, avoiding the fractures which plague their polycrystalline counterparts. “Our new synthesis strategy enhances the durability of nickel-based cathode materials,” Park explained. “We will continue our research to make secondary batteries for electric vehicles cheaper, faster and longer-lasting.” This research, published in ACS Applied Materials & Interfaces, highlights the link between calcination temperature, microstructure and long-term battery performance. The findings could transform how EV batteries are designed, improving not just durability but also affordability and sustainability.

The main focus of our research was to understand how damage and fatigue inside a battery progresses over time, and how we can prevent it. In the study, researchers compared the long-lasting single-crystal electrode with a more commonly used polycrystalline electrode. The two electrodes are made from similar materials, but in the polycrystalline electrode, those materials take the form of many tiny particles formed from even smaller crystals packed together. In the single-crystal electrode, as the name suggests, each particle is made from just one crystal, which makes them more resistant to mechanical strain. Cathode materials are key to improving energy density, which directly affects driving range. One approach has been to increase the amount of nickel in the cathode. While this boosts energy capacity, it also introduces problems. High-nickel cathodes tend to develop cracks and suffer from faster performance decline over time. These failures result from how lithium ions interact with the crystal structure. When too much lithium leaves the material during discharge, the structure collapses in one direction. This stress leads to tiny cracks between grains, weakening the material and reducing how many charge cycles the battery can handle. To solve this, researchers have tried different strategies, adding coatings, doping the material with other elements, and designing better internal structures. But one of the most effective methods has turned out to be controlling the cathode’s microstructure. A well-designed structure with balanced grain size and pore distribution can absorb stress more evenly and slow down degradation. That’s where calcination temperature comes into play. Below 850 °C, the material retains small, well-distributed pores which cushion stress. But once that threshold is crossed, the structure changes dramatically. Polycrystalline cathodes lose their pores and become brittle. On the other hand, single-crystal cathodes made at this same high temperature avoid cracking because they have no grain boundaries, offering much better durability.

After 2.5 years of constant cycling, the polycrystalline electrode was full of tiny cracks. Those cracks form when the lithium ions in the battery force the atoms in the electrodes apart and limit how much energy the battery can store. By contrast, the single-crystal electrode contained few cracks, even after charging and discharging continuously for six years. This suggests that battery life hinges more on how the cathode is structured than on how perfect the crystal is. It also opens the door for longer-lasting EV batteries that don’t sacrifice power for endurance. The battery with the single-crystal electrode had gone through more than 20,000 charging and discharging cycles and had retained about 80% of its original capacity in that time. A typical electric vehicle can travel about 250 miles (400 km) on a charge, so the battery with the single-crystal electrode has a lifespan equivalent to driving about 5 million miles. For comparison, typical EV batteries today need to be replaced after about 200,000 miles (322,000 km). We really need these vehicles to last as long as possible, because the longer you drive them, the better its improvement on the carbon footprint is. Even with better battery performance, another challenge looms, what happens when EV batteries reach the end of their life? As more vehicles hit the road, the number of used batteries is set to surge. If not handled properly, these batteries can cause serious environmental damage. Lithium-ion batteries contain heavy metals like cobalt, nickel and manganese. If these materials leak into the ground, they can poison soil and water. Mining new raw materials is also a major environmental burden, consuming large amounts of water and energy while leaving behind toxic waste.

Recycling these batteries is not easy. It’s expensive and energy-intensive, requiring specialized equipment. Still, scientists are working on better ways to recover valuable metals. One method, called hydrometallurgy, uses chemicals to dissolve and separate metals for reuse. Another method, direct recycling, restores parts of the battery, like the cathode, without breaking them down completely. Many used EV batteries still hold 70–80% of their original storage power. These can be repurposed for less demanding uses, like storing energy from solar or wind farms. Researchers are exploring how to give these batteries a “second life,” reducing waste and extending their usefulness. There’s also a push to develop new types of batteries which are easier to recycle. Solid-state and sodium-ion batteries are two promising options. They use safer materials and simpler designs, which could lower the cost and impact of battery disposal. Governments are making rules which require battery makers to take back used batteries. Others are offering incentives to encourage recycling and building better systems for collecting and processing old units. The path to sustainable transportation doesn't end with building better batteries, it also means managing their entire lifecycle, which includes how they’re made, used and eventually discarded.

By understanding the role of microstructure in battery performance, researchers have taken a major step forward. Single-crystal cathodes produced at critical temperatures could offer longer-lasting and more reliable energy storage for electric vehicles. This would reduce the need for frequent replacements and ease pressure on global supply chains. At the same time, improving recycling systems and repurposing spent batteries can help solve the growing waste problem. These efforts not only reduce environmental harm but also make electric vehicles more attractive and affordable in the long run. With innovations in material design, recycling and policy, the future of EVs looks more sustainable than ever. If batteries can reliably last a million km's, it will mark a turning point for clean energy and transportation around the world. Batteries with single-crystal electrodes have yet to be incorporated into electric vehicles, although they are available commercially. Tesla has patented similar single-crystal-electrode formulations, with members of the Dalhousie team named as co-inventors. With these advances keeping batteries running longer, the battery could one day outlast other parts of an electric vehicle. When that happens, the batteries could find a second life in grid-scale energy-storage systems. There, the batteries could store renewable, but intermittently accessible energy, such as solar or wind power for all around the world.