Written for non-geeks who have an interest in learning more about the basics of Li-Ion cell development and operation, the current (pun intended) state of the art and, where experiments in Li-Ion development are headed.
"It’s helpful to start by defining what makes a battery “lithium-ion.” The stars of the show are obviously lithium atoms, which give up an electron easily to form ions. Every battery has a cathode and anode, with a separator and electrolyte sitting between the two. On the cathode side, lithium is found in a metal oxide compound, where it will stay as long as each atom is holding that electron. Once separated from the electron, lithium ions will move across the separator to collect at the anode. The freed electrons can’t cross the separator, so instead they move through whatever circuit is connected to the battery’s two electrodes.
During charging, lithium ions and electrons accumulate in the anode. During discharge, electrons flow through the circuit and lithium ions move through the separator again, reuniting as lithium settles back into the structure of the cathode material."
This article presents the history in a slightly misleading fashion.
“New battery technology is eternally five years away” is more true than they say. The keyword is new. Incremental improvements to existing technology are not usually what people are talking about when saying that nothing ever comes from new battery technology.
The newly-developed high-capacity 3.4 Ah and 4.0 Ah lithium-ion battery cells have an improved nickel based positive electrode, and the 4.0 Ah cell uses a silicon based alloy for the negative electrode instead of carbon …. The 3.4 Ah cell will be mass produced in fiscal 2012 ending in March 2012. …. The 4.0 Ah cell will be mass produced in fiscal 2013 ending in March 2013.
That 3.4 Ah cell was released in 2012 just as they said. You might recognize it as the classic NCR18650B.
While the “silicon 4.0Ah 18650” that was supposed to be released in 2013…. never happened.
They also talk about the 5%/year improvements and how that amounts to 1.5x bigger batteries over the past decade. Extrapolating from a 3.4Ah battery released 9 years ago means that we should be up to 5.2Ah 18650s now. That also never happened.
What did happen is the tech for 3.4Ah batteries became less expensive and more widespread. So the average battery got better. But the state of the art has been pretty stagnant. Going from 3.4Ah to 3.6Ah in 9 years is an 0.64%/year improvement.
And that is fine! Batteries have “enough” capacity for what we want to do. Manufactures have been improving safety and bringing down cost instead. New chemistries haven’t really tried to improve capacity.
They cite a Bloomberg article to show the progress in batteries. That chart cherrypicks a bit to draw its conclusions. For example “almost 3x in 10 years” claim relies on the existence of a 100Wh/kg battery in 2010 discrediting the 175Wh/kg battery in 2008. It is also missing the 260Wh/kg in 2012 that the NCR18650B gave us. “15% better in 8 years” doesn’t make for a good sound bite though.