Chemistry World quoted Venkat Viswanathan on the cycle life of lithium-air batteries. These batteries hold a charge greater by a factor of nine compared to lithium-ion. In interpreting the batteries’ cycle life, Viswanathan expresses a distanced view. A traditional lithium-ion battery’s life is measured by its electrical discharge. In a lithium-air battery, discharge from the reaction of lithium and oxygen determines cycle life. But because air comprises more elements than just oxygen, Viswanathan wonders how many side reactions in the electricity delivery artificially boost the cycle life. Mitigating these side reactions should pave the way to developing long-lasting lithium-air batteries.
Rechargeable lithium ion (Li+) batteries lose their ability to store charge over time. Whether they power your phone, your laptop, or your automobile, after 500-1000 recharge cycles they lose 20-40% of their capacity and must be replaced. Sony introduced the first commercial Li+ battery in 1990, but 27 years later our understanding of WHY they fail is still in its infancy. Li+ batteries have four parts: An anode (usually graphite), a cathode (usually a metal oxide), a separator membrane that is located between them, and a salt solution containing Li+. In our research, we have focused attention on one cathode material called ∂-MnO2. Our goals have been to increase the amount of energy we can store, to increase the rate at which we can deliver this energy, and to extend the lifetime of the cathode. Now, you might think that the worst way to make a battery cathode last longer would be to make it smaller! But we have discovered a process for preparing ∂-MnO2 nanowires - just 60 – 600 nm in diameter and up to a centimeter in length – that never fail, and rarely lose any energy storage capacity, across 100,000 charge/recharge cycles. In this talk, I’ll discuss these unusual nanomaterials and what they may mean for the future of electrical energy storage.
Venkat Viswanathan was featured in MIT News for his research in battery technologies. In collaboration with researchers from MIT, Viswanathan is studying a new kind of electrolyte for "self-healing" lithium battery cells, which could lead to longer driving range, lower cost electric vehicle batteries.
The high energy density and low cost of lithium-ion batteries have created a revolution in personal electronics through laptops, tablets, smart phones and wearables, permanently changing the way we interact with people and information. We are at the threshold of similar transformations in transportation to electric cars and in the electricity grid to renewable generation, smart grids and distributed energy resources. Many aspects of these transformations require new levels of energy storage performance and cost that are beyond the reach of Li-ion batteries....
Energy expert Venkat Viswanathan have received funding from the U.S. Department of Energy’s Advanced Research Projects Agency – Energy (ARPA-E) to study the use of dendrite-blocking polymers in lithium-ion batteries.
When charged repeatedly, lithium-ion batteries run the risk of overheating, and even catching fire. This is due to the formation of dendrites, or microscopic fibers of lithium that can form during the charging cycle. Over time, these dendrites can grow long enough that they connect the battery’s electrodes to one another, causing the battery to short-circuit and become a potential hazard. In order to fully implement future lithium-ion battery technologies, which could greatly increase the battery power of our smartphones, electric vehicles, and more, engineers need to find a way to stop these dendrites from forming.