Siliconâ€™s high theoretical charge capacity has inspired a tremendous amount of research into the possibility of using it to replace at least part of the graphite in lithium-ion battery anodes. However, Si presents major technical challenges. It can undergo a volume change of up to 300% during charging and discharging, limiting cycle life.
Michigan-based Paraclete Energy claims to have made significant progress on the road to storing more energy with silicon.
â€œWe believe that one of the reasons others are struggling with silicon is because most of those companies arenâ€™t silicon experts; theyâ€™re battery experts,â€ CEO Jeff Norris told Charged. â€œOur strength is that we come out of the silicon industry. We know how to make the silicon functional from a cycling perspective. What weâ€™re really selling is our expertise â€“ we partner with customers and help them develop a better anode using silicon.â€
â€œThere are a lot of companies using new groundbreaking methods that are really cool, but most of these techniques were recently developed in government labs or university projects, and theyâ€™re very exotic,â€ said Norris. â€œThe problem is that the latest and greatest ways to make silicon donâ€™t necessarily create the best or most cost-effective material to improve todayâ€™s batteries.â€
â€œItâ€™s actually very easy to make a silicon-anode battery, but itâ€™s difficult to get it to cycle without capacity loss,â€ Norris explains. â€œThe trick is to make the silicon particles very small and cost-effectively, while passivating the surface of the silicon with a compatible and conductive surface modifier that protects the silicon during the charging cycle. Weâ€™ve been able to do that using kinetic manufacturing techniques and surface-modifying additives.â€
â€œUltimately, we can add considerable amounts of silicon to existing graphite anode formulations â€“ anywhere from 8 to 25%, depending on the customer. That is enough to double to quadruple the anodeâ€™s capacity and experience no noticeable reduction in cycle life.â€