New silicon anode can replace graphite to enhance lithium battery capacity and life

Researchers at the University of Waterloo have developed a new way to dramatically increase the critical performance of commercial lithium-ion batteries. It uses a new silicon anode to replace the common graphite anode, in addition to being smaller, lighter and more durable, but also can be applied from personal devices to electric vehicles and other fields. As a negative electrode material in the field of lithium-ion batteries, the use of graphite has been relatively smooth, but its drawback is also obvious that it is difficult to enhance capacity. As it can only store relatively little energy (about 370 mAh / g), researchers are eyeing the increasingly popular silicon material (up to 4200 mAh / g). Of course, the latter is not without limitations. During each charge cycle, silicon in a cell expands and contracts by up to 300% when interacting with lithium. As time goes on, it will significantly reduce the performance of the battery, short circuit, and eventually lead to battery scrap. To overcome this problem, others have recently attempted to design nano-sized sponge-like silicon anodes for batteries, with silicon nanowires as few microns long and even mixed with graphite and carbon nanotubes. However, scientists at the University of Waterloo have developed another way to modify the structure of silicon anodes. It takes advantage of the chemical reactions between doped graphene, nanosilica particles, and cyclized polyacrylonitrile (commonly used in the manufacture of surgical gloves) to form a robust nanostructure. After testing, the researchers found that this anode design can reduce the contact between the lithium and the electrode, thus avoiding most of the expansion and contraction, eventually resulting in higher stability of the battery. In addition, they claim to store up to 1000 mAh / g of energy, 2275 cycles (500 cycles versus graphite), and 99.9% Coulombic Efficiency. Previously, the charge transfer of silicon anodes has been seen as another weakness. The researchers said the new anode boosts the energy density of Li-ion batteries by 40% to 60%, so we expect to see EVs up to 500 kilometers (310 miles) long after a single charge. The study, published in a recent issue of Nature Communications, is expected to commercialize in the coming year.