A number of research efforts are under way at the university level to use nanotechnology to improve the composition of lithium-ion batteries. Now one of these efforts at Northwestern University has gone commercial.
The startup SiNode Systems is using a combination of graphene and nanoparticles in its effort to build a better battery. It was formed last year 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.
The structure of SiNode Systems' lithium-ion battery design combines silicon nanoparticles with a graphite-based scaffolding material that offers a layer of protection.
(Source: SiNode Systems)
"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.
Lithium-ion batteries have become the norm for myriad personal electronic devices and electric and hybrid automobiles, but the batteries historically degrade quickly and lose their charge over time. There are also limitations on how long they last. These factors have a number of researchers looking for better designs.
SiNode says on its website that the key to its approach is layering its silicon nanoparticles with a graphene scaffold-like material to help "eliminate the rapid degradation of performance associated with silicon-based anode materials."
Lau said the battery under development offers an increased charge capacity and a recharge rate of up to 10 times the norm for lithium-ion designs. It also features stable performance that can last hundreds of cycles.
The initial capacity of the SiNode anodes is approximately 3,200 mAh/g, versus 370 mAh/g for current graphite anodes. Moreover, SiNode says on its site that its high-energy-density anodes "allow for both a smaller battery form factor and extended range of use."
In addition, Lau said the battery's design is more environmentally friendly. The fact that it creates a new anode form factor in sheet form (rather than powder) makes it "cheaper to integrate into a full battery."
Two other projects are using similar methods but have not been commercialized. One of these projects, out of the University of Southern California, replaced the graphite anodes typically used in these batteries with silicon nanowires with pores. The other project, out of the University of Maryland, replaced the graphite with nanoscale beads of silicon about 10,000 times thinner than a piece of paper. Like SiNode, the researchers behind these projects say they can dramatically increase the lifetime of lithium-ion batteries and reduce charging times.
SiNode is initially targeting intelligence agencies and the consumer electronics market with its batteries, and Lau said it is conducting validation testing to come up with a battery that can be mass produced. "We believe our anode could be as ubiquitous as the lithium-ion battery itself."