Cohort 3 (2021): Gigafactories, Cell Chemistry and Grid-Scale Storage

When Cohort 3 met in December 2021, the battery industry course brought together people who wanted to see the whole value chain at once, from the atoms inside a cathode to the megawatts a stationary system feeds back into a grid. The sessions ran wide that season. Over ten lectures and more than twenty office-hour talks, our cohort explored how a cell is designed, how a factory is built to make millions of them, and what happens to those cells once a first life ends.

This recap pulls together the themes that kept surfacing across the term, so you can see what a working battery professional was thinking about at the close of 2021. The mix was deliberate. Some sessions came from academics working on next-generation materials, others from engineers running production lines, and others still from people building and financing storage projects. That range is the point of a battery industry course: the field is too interconnected for any one specialism to make sense on its own. An investor needs to grasp why chemistry choices constrain cost, and a materials scientist benefits from knowing how a grid operator actually dispatches a battery. Cohort 3 was built to let those perspectives sit in the same room.

From materials science to the finished cell

A recurring thread ran through the chemistry sessions. The cohort spent real time on lithium-ion cathode materials and on anode technology, treating them not as abstract science but as choices with cost, performance and supply consequences. When you understand why a nickel-rich cathode behaves differently from an iron-phosphate one, the trade-offs in an EV pack stop being mysterious.

The anode discussions went further than graphite. One participant talk examined a net carbon negative anode for lithium-ion batteries, which connected the chemistry directly to the emissions conversation happening elsewhere in the term. Another explored solid-state research on a sacrificial layer for the electrode interface, a reminder that the field was already looking past today's liquid electrolytes. These were not idle science lessons. A cathode choice sets the energy density, the cost and much of the safety profile of a cell, and an anode choice governs how fast it can charge and how long it lasts. For anyone trying to judge a battery product or a company's roadmap, being able to read those material decisions is a genuinely useful skill, and the cohort treated the chemistry sessions as training for exactly that judgement.

Diagnostics tied it all together. A lecture on studying battery behaviour using electrochemical impedance spectroscopy (EIS) showed how researchers read the internal state of a cell without taking it apart, and office-hour talks on electrical testing in research and production, and on battery monitor testing, grounded that theory in what a lab or line actually measures. The through-line was that a modern cell is a designed object, tuned at the material level for a particular balance of energy, power, cost, safety and longevity. There is no single best chemistry, only the right chemistry for a given application, and the cohort spent its time learning to reason about those trade-offs rather than memorise a winner.

Building the factories

If 2021 had a single loud theme, it was manufacturing at scale. The cohort explored battery giga manufacturing and the practical question of how to set up a cell production line, which is a very different problem from making a good cell in a lab. Coating an electrode uniformly, at speed, without defects is its own engineering discipline, and one participant who worked as an electrochemical process engineer on electrode coating spoke directly to that.

The geography of manufacturing came up repeatedly. Sessions surveyed gigafactories across the UK and Europe, and a detailed comparison of the 4680 cylindrical cell format showed how a single design decision ripples through pack architecture and factory tooling. Mass customisation was another angle: how energy storage deployments scale when every site has slightly different requirements but the supply chain still needs volume.

Underneath the factory talk sat the materials question. A supply-and-demand session on critical battery commodities laid out why lithium, nickel and cobalt availability shapes everything upstream, and a memorable talk explored mining lithium from seawater as one long-term answer to that constraint. The cohort also looked at the workforce and equipment side, from the electronics that sit inside every pack to the EV charging infrastructure and supply equipment that a growing fleet depends on. A factory is only one link in a long chain, and 2021 was a year in which almost every link was being scaled at once, which put strain on materials, machines and skilled people alike.

Storage, second life and the grid

The cohort explored where batteries go once they leave the factory. Several sessions looked at stationary energy storage and energy storage technologies in the power system, including the design choices and critical points in utility-scale BESS deployment. These were the practical questions: siting, safety, dispatch and how a battery earns its keep on the grid.

Two threads gave this section its character. First, second-life batteries: a session on developing a roadmap for reusing EV packs treated retirement as an opportunity rather than a waste problem. Second, traceability. A live demonstration of battery traceability software showed how ma