Battery technologies

[Mike Watterson]

Nickel-metal hydride. Still widely used. Better than NiCd and no nasty cadmium

Lithium ion. A big step in energy density (both for weight and size). The dominant technology for cars, power tools, portable electronics. Our world would look very different if they didn't exist.

Actually the main difference on capacity after 200 full cycles on NiMH and Lithium Ion is weight. Not volumetric capacity.
In 1970s the NiCd AA was about 450mAH. Early NiMH AA were 500mAH, slightly over 3,000 mAH is now possible. At larger sizes the volumetric efficiency is higher than AA.
The advantages of LiIon are lower self discharge (irrelevant for a laptop?) and much much lower weight. The disadvantages are higher risk of fire or explosion and complex charging. Obviously the single cell voltage (4.2 V down to 3.7 V) and flat aspect radio is an advantage for things like phones, tablets and ereaders. The shape is handy for stupidly too thin laptops.

I'd disagree with the last point (my emphasis). Our world would look very different if they didn't exist
Certainly the rechargeable Lithium batteries are very good, but development has slowed. Lifetime is poor compared to non-gel Lead Acid or Nickel-anything and NiMH have improved x3 in capacity and down to about 1/4 to 1/10th of self discharge since LiIon replaced NiCd and NiMH in laptops and power tools.
Households and workshops now have many LiIon rechargeable things out of fashion and marketing rather than it making any sense (heavier for same power than mains cord version and less environmentally friendly).

NiMH mobile phones, DECT phones, two way radio, gadgets and power tools arn't much different to equivalent tech Lithium powered versions.