ATU researchers are energised by new discovery that could make smartphone batteries safer and cheaper.
Researchers at Atlantic Technological University (ATU) are developing a technique for safer, longer lasting lithium-ion batteries – the most commonly used batteries in rechargeable devices including smartphones, laptops, e-scooters and power tools.
These popular batteries can be highly flammable if not manufactured, handled, stored or disposed of correctly, with devices catching fire and product recalls issued.
Just last month, the US Consumer Product Safety Commission issued a warning to stop using lithium-ion batteries for a range of Rad Power e-bikes, stating that the “hazardous batteries can unexpectedly ignite and explode”. And many people will remember Samsung’s global recalls of its newly released Galaxy Note 7 in 2016 after reports of the batteries catching fire. This ended up being one of the largest product recalls in history, with 2.5m phones recalled and reports at the time suggesting it cost the company upwards of $5.3bn.
One of the main issues with these batteries is thermal runaway – where the battery gets into an uncontrollable, self-heating state that can cause extreme heat, fire and smoke.
To tackle this issue, PhD researcher Keith Sirengo, Prof Suresh C Pillai and the team at ATU, in collaboration with Dr Libu Manjakkal at Edinburgh Napier University, have looked at the makeup of these lithium-ion batteries to develop a safer solution.
Lithium-ion batteries are made up of the anode (negative), cathode (positive), electrolyte (liquid or gel that allows the electrically charged ions to move between the anode and the cathode) and separator (a barrier between the anode and cathode that is permeable to the ions).
The research team noted that a layer that forms on the anode’s surface can be unstable, limiting the battery’s performance. This layer, known as the solid electrolyte interphase (SEI), is supposed to protect the battery, but during charging and discharging, it can repeatedly crack and reform, wasting lithium and electrolyte in the process. Over time, this leads to poor battery life, reduced performance and, in some cases, the formation of dangerous growths called lithium dendrites that can pierce the separator and cause short circuits or fires, the team said.
Lead researcher Sirengo found that using a unique imidazolium-based ionic liquid in the electrolyte significantly extends battery life.
Instead of the unstable SEI layer, this new ionic liquid facilitates the formation of a stable protective layer on the anode. The layer lowers resistance, allowing lithium ions to move more easily, which makes the battery safer and longer lasting.
Sirengo also found that letting the battery ‘age’ for about 16 days encourages the formation of a stable ‘solvent-anion complex’. This process reduces voltage losses and improves the battery’s ability to recharge efficiently. The method is simple, cost-effective and suitable for large-scale production.
However, the team found that a side effect of this approach was a slight reduction in the rate of ionic conductivity and overall efficiency of the battery.
The team said that further research is needed to formulate this new, more stable layer in a way that maintains battery performance.
“Electrolyte formulation and lithium-metal protection are essential for unlocking the full potential of high-energy lithium-metal batteries in terms of safety and longevity,” said Sirengo.
Pillai, principal investigator on this project and an expert in nanotechnology, said that this research “highlights how targeted electrolyte engineering can address some of the most persistent challenges in lithium metal batteries, including dendrite formation, limited cycle life and safety risks”.
“Ultimately, this work emphasises the importance of understanding and controlling interfacial reactions at the molecular level to unlock the full potential of next-generation energy storage systems,” he said.
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