Happy New Year!
To start the year off right we are updating our cathode materials post to keep up with the changing times. The table of materials now holds 8 different cathodes so it is hosted on our website for easy reading. Enjoy!
Cathodes are where battery performance goes to live or die, where some people immediately get overwhelmed, slide decks tend to get optimistic and lifetime data quietly disappears.
They’re the biggest cost driver in a lithium-ion cell, the main determinant of energy density, and the place where companies most often fall in love with the wrong thing.
Let’s get into it.
Cathodes
The cathode is the battery’s positive electrode and biggest cost driver: around 50% of the cell price. Daqus Energy has a great infographic on the cost of the cathode. This is why cathode selection is rarely a purely scientific decision, it is a supply chain, warranty, and geopolitical decision wearing a lab coat.
In most lithium-ion batteries both the cathode and the anode are intercalation hosts that lithium-ions can reversibly move in and out of, with lithium-ions and electrons moving towards the negative electrode (“anode”) during charge, and towards the positive electrode (“cathode”) during discharge, as shown in Figure 1.
Figure 1: A lithium-ion battery with LCO as the cathode and graphite as the anode.
When choosing a cathode, the relevant question is not “which chemistry is best,” but which tradeoffs matter most for the application.
Changing the cathode chemistry doesn’t just change energy density. It changes thermal management, pack design, warranty risk, supplier exposure, and even recycling economics.
What matters when choosing a cathode:
Gravimetric & volumetric energy density (Wh/kg, Wh/L)
Wh/kg tells you how light a pack can be
Wh/L tells you how big it has to be — and how much thermal, structural, and packaging overhead you inherit
Cycle life & calendar life (how many cycles before capacity falls to e.g. 80%)
Power / rate capability (C-rate performance)
Safety / thermal stability (thermal runaway, oxygen release)
Cost & supply chain / critical materials (cobalt, nickel content; geographic concentration)
Scalability and manufacturability (synthesis complexity, coating requirements)
Optimizing one of these almost always makes at least one other worse. Anyone claiming otherwise is either early in development or early in fundraising.
Some Resources We Love:
This paper covers the history of the Li-ion battery very thoroughly, but only covering up to 2016.