Tiny batteries for your cell phone or camera that can hold days of charge? Although it may seem like fantasy, this is the goal for researchers looking into new materials for lithium (Li) – ion batteries. Current state-of-the-art technology uses a graphite anode, which is the electrode in the battery where the Li is stored during charging of the battery and discharged during use.
The capacity of the anode is a crucial quantity, as it relates to how much charge can be stored in the battery and used before needing to plug it in to recharge. Capacity depends mainly on the chemistry and binding between the anode and the Lithium. Theroetically, silicon should have about ten times the capacity of graphite, however it’s been difficult for researchers to find a way to develop cheap silicon electrodes that don’t expand and break when charged with lithium.
A number of research efforts are under way at the university level to use nano silicon to improve the composition of lithium-ion batteries. Now some of these efforts have gone commercial.
1. The startup SiNode Systems is using a combination of graphene and silicon nanoparticles in its effort to build a better battery. It was formed in 2012 out of a research project by Cary Hayner (now SiNode’s CTO) under the direction of Harold Kung, a Northwestern professor of chemical and biological engineering.Joshua Lau, SiNode’s co-founder and a member of the research team, told us the startup is developing a high-performance, high-capacity lithium-ion battery by creating a composite anode — the place where electrical current flows into the battery — out of silicon and graphene.
“Our anode design is unique because it leverages the strengths of two separate components — silicon and graphene — to create a composite anode that is high capacity, fast charging, and stable — three attributes that no other anode can claim,” he said.
2.Researchers at Stanford University have developed a new lithium-ion battery design that uses porous silicon nanoparticles in place of the traditional graphite anodes to provide superior performance. They replaced the graphite anodes typically used in these batteries with silicon nanowires with pores.The new batteries-which could be used in anything from cellphones to hybrid cars-hold three times as much energy as comparable graphite-based designs and recharge within 10 minutes.Now this technology has gone commercial by a newly founded company: Amprius. Amprius’s silicon anode technology was originally developed at Stanford University and enables dramatic improvements in the energy density and specific energy of lithium-ion batteries. Amprius is backed by some of the world’s leading investors, including Trident Capital, VantagePoint Capital Partners, IPV Capital, Kleiner Perkins Caufield & Byers, SAIF Partners, Chinergy Capital, Google Chairman Eric Schmidt, and Stanford University.Until Feberuray, 2014, Amprius can manufacture 650Wh/L high energy battery and has become supplier and designer for some International brands. Future research by the group will focus on finding a new cathode material with a high capacity that will pair well with the porous silicon nanowires and/or porous silicon nanoparticles to create a completely redesigned battery.