Battery breakthrough could extend range of next gen EVs

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Next generation electric vehicles could soon run for longer and at a lower cost thanks to a breakthrough in battery technology made by researchers at Rice University.

The team, led by engineer Sibani Lisa Biswal and research scientist Madhuri Thakur, has created a high capacity, low cost anode material with 'serious commercial potential' for rechargeable lithium batteries. In testing, the silicon-based anode was said to deliver 600 charge-discharge cycles at 1,000 milliamp hours per gram (mAh/g) - a significant improvement over the 350mAh/g capacity of current graphite anodes. While silicon can hold 10 times more lithium ions than the graphite commonly used in anodes today, it more than triples its volume when completely lithiated. When repeated, this swelling and shrinking causes silicon to quickly break down. To combat this, the Rice researchers began making porous silicon films. After these proved difficult to handle and even more difficult to scale up, they decided to crush the porous silicon to form porous silicon particulates, a powder which they claim can be easily adapted by battery manufacturers. "As a powder, the silicon films can be used in large-scale roll to roll processing by industry," Thakur noted. "The material is very simple to synthesise, cost effective and gives high energy capacity over a large number of cycles. This work shows just how important and useful it is to be able to control the internal pores and the external size of the silicon particles." The next step for the team, according to Thakur, will be to test the porous silicon powder as an anode in a full battery. "Our preliminary results with cobalt oxide as the cathode appear very promising, and there are new cathode materials that we'd like to investigate," she concluded. The work was carried out in partnership with defence and aerospace firm, Lockheed Martin. The findings have been reported in the journal Nature.