UAlbany NanoCollege licenses silicon/silicide chemistry and branched nanostructure for advanced Li-ion batteries to spin-out
6 October 2012
|BESS Technologies anode performance, capacity vs. cycle number. Source: BESS Tech. Click to enlarge.|
The College of Nanoscale Science and Engineering (CNSE) of the University at Albany in New York has licensed a silicon/silicide nanostructured anode technology developed there for Li-ion batteries to spin-out company BESS Technologies. The agreement enables BESS to begin to commercialize and to scale-up the technology.
BESS (Battery Energy Storage Systems) Technologies is a component design and engineering firm started by a group of CNSE graduate students in 2010. The CEO and co-founder is Dr. Fernando Gómez-Baquero, a nanoengineer and economist with more than 10 years experience in nanotechnology research and in launching nanotechnology startups. Issac Lund, the CTO, is one of the co-inventors on the technology patent.
The technology represents another approach to enabling the use of silicon-based anode materials to enable a significant increase in battery capacities; the graphite used in the anodes of many current Li-ion batteries has a capacity of around 372 mAh g-1, while silicon theoretically offers a capacity of more than 4,000 mAh g-1. However, silicon undergoes major expansion during the insertion of Li ions, and the stress causes the silicon to degrade over time, resulting in poor lifetime and degrading battery capacity. Numerous research groups are exploring ways to counteract that property to enable a commercially viable silicon anode material. (Earlier post.)
Working at CNSE’s Albany NanoTech Complex, the BESS team developed an innovative process to build branched nanostructures which offer significantly increased energy storage capacity, faster charging rates, and a longer lifetime. The branched, flexible nanowires relieve the stress of lithium ion insertion. These structures offer several advantages, the researchers claim:
The surface area of the branched nanostructures is increased significantly over that of thin film or non-branched nanostructures of the same footprint.
The flexibility of these nanostructures mitigates the problems with stressing due to their ability to flex. This allows for the required expansion area needed for lithium insertion and silicon expansion.
Each branch of the nanostructure is connected to a trunk structure and each trunk is well-connected to the substrate electrically and mechanically. The branched nature of the nanostructures of the invention allows for a higher anode density, thus requiring less area for same charging capacity.
|An illustration of the branched nanostructure from the patent document. Click to enlarge.|
The core of the nanostructure is a resistive semiconducting material and the shell is a lower-resistance current collecting material; the current transfer occurs in the shell, not in the core. This nanostructure is then coated with an electroactive or electrically conductive coating that acts as the capacitive material. The anode technology does not require the use of carbon or any type of binder, unlike some other silicon anode technologies under development.
Incorporation of catalyst particles into nanostructures changes the electrical and/or chemical characteristics of the outside shell. As an example, the conductivity of a nickel silicided nanostructure can be adjusted by changing growth parameters to make the silicided region thicker. An additional surface coating may also be utilized to change the nanostructures’ properties.
The BESS Tech team has submitted a paper with more details regarding the technology to the Journal of Power Sources, according to Gómez-Baquero, who says that BESS is now consistently obtaining around 1,200 mAh g-1 with very stable behavior that goes beyond 500 cycles. The JPS paper will describe some half cells that were tested beyond 1,000 cycles. The team has charged at 5C-10C without damaging the anode.
BESS is not a materials company, Gómez-Baquero emphasizes. The company designs components such as the anode, tweaking the manufacturing “recipe”—i.e., controlling the process parameters—to improve their performance. The company is are working to make several “recipes” based on the same nanoengineering core knowledge he said.
We license designs (recipes) to manufacturers. Some manufacturers prefer to use their own equipment to manufacture, in which case we help them lay out production plans. Other manufacturers prefer to receive a fully manufactured anode, in which case we seek the help of a foundry (outsourced manufacturer). We are currently working with two companies in NY State that want to pursue this foundry model.—Dr. Gómez-Baquero
In addition to the licensing agreement, BESS will have continued access to the cleanrooms, laboratories and tooling at CNSE, providing further stability as the company grows.
CNSE has already assisted BESS in obtaining more than $800,000 in funding through technology programs offered by the New York State Energy Research and Development Authority (NYSERDA) and the National Science Foundation’s (NSF) Partnerships for Innovation program.
The UAlbany CNSE is dedicated to education, research, development and deployment in the emerging disciplines of nanoscience, nanoengineering, nanobioscience and nanoeconomics.
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