What can chemistry do for me?

This article appeared at Zbattery.com some time ago. I see it needs some updating so I'll reprint it with edits here:

What does Battery Chemistry matter to me?

There are many different chemistries for batteries, each having different facets including: capacity per volume (energy density, shown in the table below as Wh/l) capacity per weight (specific energy, shown in the table below as Wh/kg) capability to deliver current capability to accept charge current price the number of cycles. There are other differences, too, like what temperature range a chemistry will work well within and how quickly a cell will discharge in storage. But the main differences are listed above so that is all we will consider at this time. The obvious question is - Why don't we just use the best chemistry? It's because the differing chemistries have tradeoffs in the main factors listed. There is no best one, just the best one for a particular application. Non-rechargeable Batteries Generally, non-rechargeable batteries have greater capacities than their rechargeable counterparts. They also generally stay charged in storage better. For example; An alkaline AA battery will have a rated capacity of about the same as a single charge of a NiMH AA battery, but the alkaline battery has a higher voltage, meaning overall it delivers more energy. In a typical lower-current application like a small radio, the alkaline batteries should last you about 30% longer than a NiMH AA in the same place. And if the radio isn't used much, the better storage life of the alkaline cells make them easier to work with, not to mention pennies compared to dollars in initial costs. Non-rechargeable lithium has some amazing specific energy and energy density. That's why when capacity is the most important factor, non-rechargeable lithium is king when recharging is not a practical option. Why is recharging a battery not always a practical option? Rechargeable batteries would be great to use all the time because the electricity for a recharge is very little money compared to buying a whole new battery. But there are other costs - The cost of replacing the battery more often, and up-front costs that are much higher than non-rechargeable counterparts. And there is more management involved with switching out discharged batteries with charged replacements. So why don't we use the best of each type; rechargeable and non-rechargeable? Because trade-offs are made with every type of battery chemistry. Which, unfortunately, means we have to pay attention to the different properties of each type. Still, the first difference we note is between non-rechargeable and rechargeable. As far as non-rechargeables go Alkaline is inexpensive, although it doesn't store as well or deliver current as well as some other chemistries. Lithium is expensive and doesn't deliver current as well as some other chemistries (although lithium's higher voltage makes up for this somewhat). Then there is 1.5V lithium, which is a monopoly product by Energizer that is a special case in its own right. There are a few more non-rechargeable chemistries that have niche markets and I'll probably go over them in a future post. Still, when a company designs a product, they generally have to decide on either alkaline or lithium because alkaline is about 1/2 the voltage of lithium. To make it for both, such different voltages would drive up the cost. As far as rechargeables go This could be a topic unto itself. Because the nature of recharging is so attractive designers would like to use it if they can. And a lot of chemical engineers have thought of a lot of different cell types to address problems by designers. But they haven't found a chemistry that will address all problems. Thus, designers use rechargeable chemistries based on cell factors are most important to their design. Some specs on the main chemistries Here is a list of chemistries and their capacity per weight and volume. There are many sub-chemistries and varying constructions used to make the above cells, so these numbers are a general rule-of-thumb comparison: (Watt-hours per kg / Watt-hours per liter) Lead acid 40/100 Alkaline 110/320 Non-rechargeable lithium 700/1100 Silver oxide 130/500 NiMH 90/250 Lithium-ion 150/330 LiFePO4 105/210