"Reasoning from first principles" is just a bullshit way of saying, analogise using fundamentals and don't hand-wave or fit to a narrative when you have empirical data.

The example with material constituents of a battery is still reasoning with analogy - you had to draw analogies with other problems with similar solution structures: the important thing here was knowing the fundamental principles about satisfying economic problems, and the scientific domain knowledge relating to the creation of a high-quality battery.