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I'm writing about a setting which will be developing an industrial civilization on a planet similar to Earth in relevant ways, except that certain heavy metals such as lead, are much rarer. (Other elements, in particular middleweight metals like iron and copper, have about the same abundance as they do on Earth.)

For many of the things for which we use lead, there are good substitutes. Iron works fine for bullets; ceramics and brass make non-toxic pipes; there are lead-free solder alloys.

But what about lead-acid batteries? I'd like to say lithium is better, or I remember sodium-sulfur being another alternative battery chemistry that was in use for a while. But lead-acid has been oddly persistent, still in use in regular car batteries even today despite the use of lithium for other kinds of batteries.

What accounts for the persistence of lead-acid batteries, that makes them so hard to replace? What would be the best substitute, on a world where lead is not an option?

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    $\begingroup$ What's wrong with Edison's nickel-iron battery? Nickel-iron batteries have been used in railway applications for a very long time. They have very long useful lives, they require little maintenance and back in the day they have also been used in early electric cars such as the 1909 Baker Victoria Roadster. (They have also low energy density, but the question asks for alternatives to lead-acid batteries, so...) $\endgroup$
    – AlexP
    Jul 6, 2021 at 4:27
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    $\begingroup$ Nickel-iron batteries don't seem to have the high current discharge rate capability needed to run an automotive starter motor that lead-acid batteries do? $\endgroup$
    – GrumpyYoungMan
    Jul 6, 2021 at 4:53
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    $\begingroup$ @GrumpyYoungMan: Put more of them in parallel? They powered electric cars, which clearly required quite a bit of power. $\endgroup$
    – AlexP
    Jul 6, 2021 at 5:42
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    $\begingroup$ About what makes lead-acid batteries so tenaciously persistent: they are cheap, they have long-ish useful lives in horrible conditions (very cold, very hot) with no maintenance, they are very easily recyclable, and they don't require advanced electronics. $\endgroup$
    – AlexP
    Jul 6, 2021 at 5:49
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    $\begingroup$ iron is not a good choice for bullets copper is better. iron is too hard and causes significant barrel wear. $\endgroup$
    – John
    Aug 4, 2021 at 2:58

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You are correct that lithium-ion is likely the best choice to replace lead-acid. Despite being invented way back in 1859, lead-acid is persistent because the technology has improved over time. Alloys were formulated to strengthen the electrodes, and technologies like sealed lead-acid (SLA) don't require maintenance. Other advantages are that lead is cheap (1/4 the price of copper), relatively easy to recycle, and that lead-acid batteries work better than even lithium-ion in cold temperatures. Aside from that, despite containing lead and sulfuric acid, lead-acid batteries are considered surprisingly safe, and sealed lead-acid, with proper venting, is both very unlikely to spill or explode. However, almost all applications of lead-acid can be easily replaced with lithium-ion.

Lithium-ion vs Lead-acid technologies

lead-acid vs lithium-ion

source: https://batteryuniversity.com/article/bu-201-how-does-the-lead-acid-battery-work

As the chart shows, the main advantages of lead-acid over lithium-ion are the cost, accessibility of materials, and safety. However, the parameters for performance, which is what matters most in order to use your battery in any application (i.e. if your battery can't provide a certain amount of power in a certain form factor, it simply won't work as a car battery), lithium-ion is comparable to lead-acid in terms of cold-cranking power (the amount of amps it can output at once), and beats it in all other metrics. It has a better cycle life-the amount of charge/discharge cycles it can go through, it can hold more energy in the same weight (and volume too but that's not in the chart), and can charge much faster too. So for most applications lithium-ion is an excellent replacement. So if your society is willing to make a few compromises (mainly in cost and safety), they'll find lithium-ion is the battery technology for them.

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