This summer, senior Anwesh Yerneni of our Chemical Engineering Department completed a highly coveted internship at Tesla, Inc. in Palo Alto, California, in which he worked on several high-profile research projects aimed at improving Tesla’s automotive batteries, the key to the automaker’s groundbreaking electric cars. Yerneni served on Tesla’s Cell Engineering Team doing research based on the company’s own in-house chemical engineering.
“The purpose of all this work is to make sure we have the most functional battery with the highest energy density, the lowest cost, and the best lifetime performance,” says Yerneni. “Tesla only makes cars that are fully electric, so having superior battery technology is essential. The battery is the key to making Tesla’s cars and energy storage from their residential or utility scale solar panels practical.
Founded in 2003, Tesla specializes in electric cars, lithium-ion battery energy storage, and, through its SolarCity subsidiary, residential solar panels. Tesla first gained widespread attention following production of its Roadster, the first mass-produced electric sports car, in February of 2008. Yerneni adds that “Tesla’s goal is to accelerate the world’s transition to sustainable energy. And the heart and soul of that effort is improving the performance of its batteries. Tesla wants its cars to have zero-emissions, not dependent on any dirty sources of energy.”
As Yerneni explains, the major bottleneck affecting Tesla’s mission to transition the world to clean energy is battery technology. Three major issues involve refining each battery’s energy density, lifespan, and cost, especially considering that the battery is the most expensive component in every Tesla car.
“Energy storage is the basis for a majority of Tesla’s efforts,” says Yerneni. “My projects would improve Tesla’s batteries even more. We want to boost the range of the battery pack so that it can go 350, 400, or 500 miles before being recharged.”
Yerneni’s personal projects on the Cell Engineering Team had to do with validating new chemistries and cell designs, along with understanding current degradation mechanisms, which are being investigated to prolong the lifetime and energy density of Tesla batteries.
As Yerneni introduces one of his projects, “For energy density, increasing the silicon content of the anode is being investigated due to silicon’s higher theoretical capacity.”
As Yerneni says, lithium ion batteries traditionally use graphite anodes, but silicon has 10 times higher theoretical capacity than graphite. As you are able to substitute silicon for graphite, you’re able to boost the capacity of a battery. “So why don’t we use silicon right now?” asks Yerneni. “What happens when the battery is charging is that silicon actually swells. So when it contracts back down to its original size, the chemical structure of the silicon and battery will be degraded. So we’re trying to attack that problem by introducing silicon in ways that its expansion and contraction do not corrupt the battery chemistry.”
As Yerneni says, “One of my main projects was to understand and quantify the various degradation mechanisms that occur as you increase silicon content in the anode. This will allow us to modify and optimize cell design for energy density.”
Yerneni’s job was to study and understand this process of expansion and contraction that happens with the use of silicon. “So in the lab I quantified the sources of degradation and in conjunction I used a computer to model this process so that our engineers can better understand the chemistry and the degradation mechanisms they are dealing with. This allows us to start modifying cell parameters to create a better cell design to stabilize silicon anodes and make them more effective in boosting energy density and battery capacity.”
Yerneni concludes that “It’s a very big issue. My work will give us a much more targeted approach to solving this problem. My work was to move this process along.”
This summer, among his many projects, Yerneni was also performing rheological characterization process development work and correlational analysis to understand and optimize the mixing process of electrodes for better electrochemical performance.
After Yerneni’s highly productive internship, he says that “I would really be interested in working at Tesla in the future. It’s hard to find a group of such highly motivated, smart, intellectual, passionate people who are working toward such a worthy mission. It was interesting, invigorating, and fulfilling."
As a ChE undergraduate, Yerneni already has a battery of important and challenging professional experiences behind him. During the summer of 2016, he worked as a lithium ion cell development engineer for Boston-Power in Westborough, Massachusetts, where he investigated contributions to impedance in their Echo 5300 cell and other cathode material and electrolytes, and he also prepared and evaluated various anode and cathode chemistries based on collected impedance data.
From May to July of 2016, Yerneni worked as an oxygen engineer intern at B/E Aerospace in Lenexa, Kansas, where, among other projects, he collaborated on a yield-improvement project for chemical oxygen generators, a project to automate the production of starter pellets and improve the design and development of the next-generation portable breathing equipment for commercial aircraft.
Since 2012, Yerneni has also worked as a Tella Sakamoto Foundation Representative, assessing the condition, maintenance, electricity, and water supply for six schools, one orphanage, and a library in rural India.
By every indication, Yerneni’s challenging undergraduate internships have already established him as a well-qualified prospective employee for numerous jobs requiring a smart, passionate, and idealistic chemical engineer. (September 2017)