Skip to Content

First Theoretical Model of Charging Cycle Performance Could Revolutionise Battery Research

Being able to simulate the change in battery performance after thousands of charging cycles could significantly accelerate battery research, say engineers

One problem with battery development is understanding how  performance changes with age. A good knowledge of this kind of degradation allows researchers to dismiss ineffective designs earlier and to concentrate on more promising ones. 

However, nobody has developed a good theoretical model of battery degradation so this kind of information has to be gathered from experiment, which can be a long and expensive task. For example, today’s lithium ion batteries degrade over thousands of cycles.

“The availability of a simple, but accurate, mathematical model of capacity fade and lifetime statistics could significantly accelerate battery development and commercialization,” say Matthew Pinson and Martin Bazant at the Massachusetts Institute of Technology in Cambridge.

And that’s exactly what these guys have developed–a simple model of the way battery capacity fades over time.

Batteries gradually degrade as the process of charging and recharging inevitably takes its toll. During this cycle, ions shuttle from one part of the battery to another, forcing themselves into lattices that are not always designed to accept them easily.

For example, when lithium ions enter a silicon lattice they cause it to expand in volume by a factor of four. That creates significant mechanical stresses during each charging cycle, which tend to tear the silicon apart. That’s why silicon, although otherwise promising, has yet to be used as an anode material. 

In lithium ion batteries, capacity fade occurs for a different reason. In this case, the electrolyte reacts with lithium at the negative electrode forming a permanent solid layer called the solid-electrolyte interphase. 

The battery continues to operate because lithium ions can travel through this layer with ease.

Nevertheless, this layer grows slowly. The reaction with the electrolyte removes lithium from the system, and after many thousands of cycles, this causes a gradual reduction in performance called capacity fade.  It is this that eventually stops the battery working. 

Pinson and Bazant’s new model simulates this process. They model the concentration gradients of lithium through the solid-electrolyte interphase and the concentration gradient of other reactive ingredients in the electrolyte. This allows them to simulate how the interphase layer evolves over time. 

“To our knowledge, this is the first attempt to theoretically predict the spatio-temporal distribution of solid-electrolyte interphase formation in a porous electrode,” say Pinson and Bazant. 

They go on to extend the model to work with other materials that rapidly degrade, such as silicon.

Of course, an important test of any model is how well it matches experimental observation. In this respect, the model works well, they say. “Our simple models are able to accurately fit a variety of published experimental data for graphite and silicon anodes.”   

That’s certainly promising but caution is always advisable in the notoriously complex world of electrochemistry. If a simple model can help to explain complex behaviour, all well and good. But there will be plenty of doubters who will need convincing.

The real test will be whether this model has predictive value in real battery research–is it reliable enough to help determine the direction of future work? 

That’s still an open question.

Ref: Theory of SEI Formation in Rechargeable Batteries: Capacity Fade, Accelerated Aging and Lifetime Prediction

Keep Reading

Most Popular

open sourcing language models concept
open sourcing language models concept

Meta has built a massive new language AI—and it’s giving it away for free

Facebook’s parent company is inviting researchers to pore over and pick apart the flaws in its version of GPT-3

transplant surgery
transplant surgery

The gene-edited pig heart given to a dying patient was infected with a pig virus

The first transplant of a genetically-modified pig heart into a human may have ended prematurely because of a well-known—and avoidable—risk.

Muhammad bin Salman funds anti-aging research
Muhammad bin Salman funds anti-aging research

Saudi Arabia plans to spend $1 billion a year discovering treatments to slow aging

The oil kingdom fears that its population is aging at an accelerated rate and hopes to test drugs to reverse the problem. First up might be the diabetes drug metformin.

Yann LeCun
Yann LeCun

Yann LeCun has a bold new vision for the future of AI

One of the godfathers of deep learning pulls together old ideas to sketch out a fresh path for AI, but raises as many questions as he answers.

Stay connected

Illustration by Rose WongIllustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at with a list of newsletters you’d like to receive.