Dinammer

Not OP either, but there is a very good chemical reason as well. Metallic lithium has an oxidation potential of 3V, relative to the standard hydrogen electrode. This is one of the highest oxidation potentials. If you could simply use up lithium as a fuel, you would get ~42.3kJ/g of lithium. This compares with gasoline at 46.4kJ/g, wood at 16.2kJ/g, and Deuterium in a fusion reactor at ~87900kJ/g.

Of course, you actually have to set Lithium up in a battery, so you only end up with an energy density on the order of ~0.36-1.8kJ/g (variance due to different chemical compositions, packaging), which still kicks the pants off of Lead Acid batteries at 0.16kJ/g. Hell, TNT is only 4.61kJ/g.

A few things to keep in mind - I didn't take into account the mass of oxygen used by combustion reactions and I just converted numbers on Wikipedia over, which are thermal densities. TNT does damage by going boom boom - a pressure wave. If you had to cart your oxygen with you for combustion on a spacecraft, gasoline doesn't look great. (https://en.wikipedia.org/wiki/Energy_density)

How to calculate the energy density: The oxidation potential is 3.04V and you get 1 mole of electrons per mole of lithium metal (6.9412g/mol) you oxidize. Using Faradays number, (96,485.34 Coulombs/moles) and that formula E = V * C, you can do the dimensional analysis, divide E by the molar mass of lithium metal, and end up with 42.25716kJ/mol, and then cut off all the excessive amounts of digits that don't matter in except in <0.1% of situations.

If you had Paul Sellers on the show I would drop everything and subscribe and listen. I don't think it's audacious claim to say he's done more to keep hand tool woodworking alive in the 21st century than anyone else.