"The battery invented 120 years before its time" I'm not sure what this article is trying to prove, the Nickel–iron battery has done its 120 years service alrea

"The battery invented 120 years before its time" I'm not sure what this article is trying to prove, the Nickel–iron battery has done its 120 years service already and it's questionable if it has a future life except in limited applications where ruggedness is needed as it's electrical capacity it's pretty terrible—as so much bulk battery material is needed for so little storage capacity and there are likely better ways of producing hydrogen. We need to put this into perspective the Nickel–iron battery has one great feature and one good feature and the rest are rather doubtful by today's standards. Their great feature is their longevity. I can recall a short but memorable news article about nickel–iron batteries of some decades ago in an electronics magazine, which I thought was in Electronics/Wireless World (but I can't find it in the index). It was a report that the Nickel–iron batteries in a London telephone exchange that were ≈80 years old had been removed from service not because they needed replacing but because they were surplus to requirements when new equipment was installed. What was memorable was that they were still working after 80 or so years after installation. The only maintenance that was needed was to replace the electrolyte (potassium hydroxide) every decade or so. The good feature of Nickel-Iron batteries is that they're reasonably ecologically sound (but even this is a little doubtful given their very low capacity—meaning more batteries are need for a given storage capacity). Frankly, they're pretty woeful when it comes to output capacity. Below are some Wiki extracts that compare nickel-iron, lead-acid and lithium iron batteries: NiFe/Nickel-Iron: Specific energy 19-25 Wh/kg Energy density 30 Wh/l Specific power 100 W/kg Charge/discharge efficiency <65% - Lead–acid: Specific energy 35–40 Wh/kg Energy density 80–90 Wh/L Specific power 180 W/kg Charge/discharge efficiency 50–95% - Lithium-ion: Specific energy 100–265 Wh/kg (0.36–0.875 MJ/kg) Energy density 250–693 Wh/L (0.90–2.43 MJ/L) Specific power ~250 – ~340 W/kg Charge/discharge efficiency 80–90%