Biologically-Inspired High-Power Batteries Poised to Charge into the Marketplace
A significant hurdle delaying the future of plug-in cars, smart grids and renewable-powered homes is the paltry performance of today’s batteries. In short, they need to be cheaper, higher in power and capacity, and safer. At the 2011 Santa Barbara Summit on Energy Efficiency, Daniel E. Morse discussed the breakthrough he and fellow researchers have made on this front and its potential to change the ways we store and use energy.
In today’s lithium-ion batteries, metal structures expand and contract with each charge, eventually becoming brittle, turning to dust and losing capacity. Nanostructures have the potential to eliminate this problem by chemically integrating the constituent materials in composites that facilitate the diffusion of ions and electrons in and out, while preventing the troublesome degradation.
Morse, Professor of Biomolecular Science and Engineering at UCSB and Member of the Production & Storage Solutions Group at the Institute for Energy Efficiency, has led the development of a biologically-inspired nanostructured battery with extraordinary properties. Speaking on his research, Morse said, “We’ve developed a generic method which is a low-temperature, low-cost, aqueous method for the synthesis of nanostructured semiconductor thin-films and nanoparticles.” The technology uses lessons gained from the skeleton-making processes of sea sponges to create a controlled catalytic reaction that produces nanocrystals of tin oxide inside grains of graphite (a commonly-used anode in conventional batteries). The material is then gently heated, transforming the tin oxide to nanocrystalline metallic tin, which are uniquely-grown inside the compliant and conductive matrix of the surrounding graphite. When the resulting “nanocomposite” is used as an anode in lithium ion batteries, the resilient graphite “breathes”, accommodating the expansion and contraction of the tin nanocrystals with each cycle of charging and discharging, preventing their disintegration. The result is an anode with exceptionally high electrical power, longevity, and low cost.
Building on these discoveries, Morse’s team has experimented with replacing the graphite in these batteries with carbon nanotubes, which are becoming cost-competitive with the former. The improved nanocomposite results in an estimated 10x more power and 40% higher energy density than conventional Li-ion batteries. This technique has also been applied to producing high-power cathodes exhibiting similar high power and capacity retention as the anodes. Together, these advancements could result in batteries readily applicable to next-generation electric vehicles, “smart-grid,” and military applications.
Finally, Morse and his colleagues have tackled the thorny problem of battery safety.
By creating a barium strontium titanate (BaSrTiO3) nanocrystalline ceramic and adding the rare earth element lanthanum (La), they have produced a material with high initial conductivity, but a rapidly increasing resistivity at high temperature. In the process, says Morse, “‘it switches from being a conductor to an insulator.” Employing this material as a coating on Li-ion electrodes could make the batteries fire-proof and explosion-proof. Because these technologies – anode, cathode, and safety coating – are produced using chemical processes, they can be readily scaled for mass production.
To take this breakthrough from the lab to the marketplace, Morse has founded a start-up company called LifeCel Technology in Goleta, CA.