Tesla’s dominance in the growing electric vehicle (EV) industry is largely attributed to its unique approach to its battery technology. The engineering behind the all-electric car maker’s cylindrical cells speaks for itself in terms of the performance and range achieved, but in a recent interview with a battery technology researcher, a few things detailed about Tesla’s batteries stood out in particular.
Ravindra Kempaiah is a Ph.D. scholar at the University of Illinois Chicago focusing on advanced battery materials for his thesis. In his interview with Tesla owner and host of All Things EV, Sean Mitchell, Kempaiah explained lithium-ion technology in EVs and the primary issues faced in their development. Overall, the biggest challenge is balancing the three main components in battery production: energy density, cost, and cycle life. Increasing one area will significantly impact the other, and the ideal equation is always being sought after. For example, if you increase energy density for higher range and lower cost, the cycle life takes a major hit. If you increase density and life cycle, the battery alone can cost as much as $100k, as described by Kempaiah.
“We always want more range. We always want higher cycle life. We want our batteries to last 15-20 years and the car to go 500 miles, but this is a problem every battery scientist has faced for the last 30 years,” Kempaiah commented in the interview.
Tesla deals with the same balancing act as other battery-electric car makers; however, there are key factors which seem to have kept the company ahead in the industry.
First, Tesla’s choice of cylindrical cells sets it apart from every other electric vehicle on the market. This provides several advantages that drive performance, flexibility, and cost control. Notably, Rivian is also using cylindrical cells, although their vehicles are not yet under production.
Out of the three types of cells available (cylindrical, prismatic, and pouch cells), cylindrical is the most cost-effective to produce. Namely, the cost per kWh is lower in cylindrical cells versus other types. The metallic jacket around the 18650 and 2170 cylindrical cells used in the Tesla Model S/X and Model 3, respectively, acts as scaffolding and provides structural rigidity to the battery. Additionally, in high powered situations, current draw and distribution of power is over the entirety of the battery pack instead of concentrated in a certain section, according to Kempaiah.
Second, Tesla uses a liquid-cooled thermal management system to manage battery temperatures whereas other automakers take a more economical air cooling approach. By adjusting the temperature of the battery pack, Tesla is able to ensure that cells are operating in their most efficient and optimal states, thereby maximizing battery longevity as well as performance. While reducing cost is an important factor in accelerating the growth of the electric vehicle market, Tesla’s investment in thermal management technology provides an upside for owners who may be looking for longevity and long-term affordability of their cars.
Third, Tesla has actively sought to limit the amount of cobalt it uses in its batteries and already uses less of the element than other companies in the Model 3 batteries. The scarcity of cobalt and its mining sources have subjected it to socioeconomic situations that are more than problematic in the United States, i.e., child labor and similar abuses are widespread in its sourcing. With this in mind, Tesla has been working on the question, “Is cobalt really needed?”
Cobalt is used as a cathode in battery technology, and out of all cathode materials available, it has the highest cost both fiscally and politically. Current consensus on battery technology says that without cobalt, the structural integrity and cycle life in batteries is compromised, as described in the interview. However, some recent scientific literature was cited by Kempaiah that indicated higher nickel content limited the impact of cobalt on batteries, possibly removing the need to use it at all. Nickel is more widely available across the globe, which keeps its cost down and mitigates the socioeconomic impacts often associated with resource mining operations. Overall, the discussion between Mitchell and Kempaiah indicated that Tesla can probably go cobalt-free soon, making it less vulnerable to the cobalt industry.
Finally, Tesla takes great care to educate its customers about proper battery maintenance, especially with regard to the negative impact of bad charging habits. Specifically, keeping an electric car battery charged at 100% for long periods degrades the battery very quickly, while keeping charging states within an optimal range will give it a long life. Tesla makes it a point to communicate to customers the importance of battery health on their overall ownership experience and value of their purchase.
When asked for his opinion by Mitchell, Kempaiah attributed the lack of education by other brands as a disconnect between engineering teams and marketing teams. While battery “best practices” are provided to EV customers by all manufacturers, the importance of communicating the true impact of bad charging habits may not be emphasized enough to be included as prominently as it should.
In summary, Tesla is constantly developing the technology in its vehicles, and its particular attention to its batteries looks to have given the company a significant advantage over its competitors. Perhaps other automakers will take a few tips from Tesla in the future, even if it’s as limited as improving communications with customers.
Watch Sean Mitchell’s full interview with Ravindra Kempaiah below: