# Other and primary batteries: Science and technology

Why zinc, magnesium and potassium are harder than they look

Source page: https://www.materialinsights.org/energy/e_other_batt/sg-sci/

What this tab covers The physics and chemistry: how the energy is stored, which materials it needs (scarcity, toxicity, recyclability) and what makes it age.

This tile covers two very different groups: emerging rechargeable chemistries that replace lithium with zinc, magnesium or potassium, and single-use (primary) cells such as alkaline, lithium coin and silver-oxide. The first is an early-stage bet on cheaper, safer materials; the second is a mature consumer product with a waste problem.

#### Mechanism
Mixed

Zinc-ion, magnesium-ion and potassium-ion cells copy the lithium-ion principle: ions shuttle between two host electrodes (intercalation) or plate onto a metal anode. Zinc-ion cells use water-based electrolytes; magnesium ions carry two charges, which promises high capacity but makes them move slowly through electrode materials; potassium-ion can reuse graphite anodes and much lithium-ion manufacturing kit. Primary cells are discharged once: an alkaline cell oxidises zinc against manganese dioxide, a lithium coin cell oxidises lithium metal, and a silver-oxide button cell reduces silver oxide. Energizer's AA alkaline datasheet gives about 2,850 mAh at a light 25 mA drain from a 23 g cell, roughly 186 Wh/kg (calculated at the 1.5 V nominal voltage, so an upper bound because voltage sags under load), and a shelf life of 10 years at 21 C on the newer sheet (7 years on an older one). For aqueous zinc pouch cells, a 2025 review estimates about 50 Wh/kg under realistic design parameters and about 110 Wh/kg only under aggressive assumptions. A 2025 review of potassium-ion batteries notes that most progress has been shown in laboratory half-cells with thin electrodes, and that full cells remain well short of commercial needs.^[2](https://cdn1.components.ru/226/226.pdf)^[13](https://pubs.rsc.org/en/content/articlehtml/2026/eb/d5eb00159e)^[14](https://digital.library.adelaide.edu.au/items/b732b874-d464-475a-ade6-e5af3cb1d53d)^[16](https://courses.egr.uh.edu/ECE/ECE2100/Archive/Spring%202024%20Honors/E91.pdf)
 AA alkaline cell (Energizer datasheet) 2,850 mAh at 25 mA, 23 g; about 186 Wh/kg at nominal voltage (calculated, upper bound)^[2](https://cdn1.components.ru/226/226.pdf) AA alkaline shelf life 10 years at 21 C (newer sheet); 7 years (older sheet)^[16](https://courses.egr.uh.edu/ECE/ECE2100/Archive/Spring%202024%20Honors/E91.pdf)^[2](https://cdn1.components.ru/226/226.pdf) Aqueous zinc pouch cell (design estimate) About 50 Wh/kg realistic; about 110 Wh/kg aggressive case^[13](https://pubs.rsc.org/en/content/articlehtml/2026/eb/d5eb00159e)

#### Material scarcity and toxicity
Mixed

Zinc, magnesium and potassium are far more abundant than lithium, but supply is still concentrated: China mined about 32% of zinc and produced about 86% of primary magnesium in 2025 (calculated), while Canada supplied about 31% of potash (calculated). Lithium remains 88% a battery metal. Silver for silver-oxide cells is a precious metal; Mexico mined about 24% of world silver (calculated). Mercury has been removed from most batteries, with indium compounds replacing it in alkaline cells, but some button cells may still contain it.^[3](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-mercury.pdf)^[4](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf)^[5](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lithium.pdf)^[6](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zinc.pdf)^[7](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-magnesium-metal.pdf)^[8](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-potash.pdf)
 China share of primary magnesium, 2025 About 86% (calculated from 950 of 1,100 thousand t)^[7](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-magnesium-metal.pdf) China share of zinc mine output, 2025 About 32% (calculated from 4,100 of 13,000 thousand t)^[6](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zinc.pdf) Mexico share of silver mine output, 2025 About 24% (calculated from 6,300 of 26,000 t)^[4](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf) Battery share of lithium use 88%^[5](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lithium.pdf)

#### Degradation and ageing
Mixed

Zinc-ion cells suffer from zinc dendrites and hydrogen gassing at the zinc anode; magnesium-ion cells struggle to find electrolytes that let magnesium plate and strip cleanly; potassium-ion electrodes swell because potassium ions are large. Laboratory coin cells flatter zinc: they often exceed 99.5% coulombic efficiency only because they use under 10% of the zinc, while high-capacity pouch cells often last fewer than 300 cycles; the best reported include an Ah-scale cell beyond 680 cycles and one keeping 88.6% capacity after 750 cycles at 53.3% depth of discharge. Potassium-ion full cells still fall short of commercial cycle-life requirements, and no commercial magnesium-ion cycle data were found. Primary cells age by slow self-discharge on the shelf.^[13](https://pubs.rsc.org/en/content/articlehtml/2026/eb/d5eb00159e)^[14](https://digital.library.adelaide.edu.au/items/b732b874-d464-475a-ade6-e5af3cb1d53d)
 Zinc pouch cells, typical Often under 300 cycles^[13](https://pubs.rsc.org/en/content/articlehtml/2026/eb/d5eb00159e) Best zinc pouch result 88.6% capacity after 750 cycles at 53.3% depth of discharge^[13](https://pubs.rsc.org/en/content/articlehtml/2026/eb/d5eb00159e)

#### Chemistries covered by this tile^[1](https://www.energy.gov/sites/default/files/2022-09/2022%20Grid%20Energy%20Storage%20Technology%20Cost%20and%20Performance%20Assessment.pdf)^[3](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-mercury.pdf)^[13](https://pubs.rsc.org/en/content/articlehtml/2026/eb/d5eb00159e)^[14](https://digital.library.adelaide.edu.au/items/b732b874-d464-475a-ade6-e5af3cb1d53d)

| Chemistry | Type | Maturity | Main issue |
|---|---|---|---|
| **Zinc-ion** | Rechargeable, water-based | Early commercial; zinc systems not yet at 100 MW scale | Dendrites, cycle life |
| **Magnesium-ion** | Rechargeable | Laboratory | Electrolyte compatibility, slow ion movement |
| **Potassium-ion** | Rechargeable | Laboratory to pilot; full cells short of commercial needs | Electrode swelling, lower energy than lithium-ion |
| **Alkaline (zinc-manganese dioxide)** | Primary | Mature mass market | Single use, waste |
| **Lithium coin (lithium metal)** | Primary | Mature | Swallowing hazard, fire risk if damaged |
| **Silver-oxide** | Primary button | Mature niche | Silver cost; some contain mercury |

#### Sources

1. [2022 Grid Energy Storage Technology Cost and Performance Assessment (PNNL-33283), Executive Summary p. vii](https://www.energy.gov/sites/default/files/2022-09/2022%20Grid%20Energy%20Storage%20Technology%20Cost%20and%20Performance%20Assessment.pdf) Pacific Northwest National Laboratory for US Department of Energy, 2022
2. [Energizer E91 AA alkaline product datasheet, older edition (Form EBC-1102G; undated, hosted by a third-party distributor)](https://cdn1.components.ru/226/226.pdf) Eveready Battery Company (Energizer)
3. [Mineral Commodity Summaries 2026: Mercury](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-mercury.pdf) US Geological Survey, 2026
4. [Mineral Commodity Summaries 2026: Silver](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf) US Geological Survey, 2026
5. [Mineral Commodity Summaries 2026: Lithium](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lithium.pdf) US Geological Survey, 2026
6. [Mineral Commodity Summaries 2026: Zinc](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zinc.pdf) US Geological Survey, 2026
7. [Mineral Commodity Summaries 2026: Magnesium Metal](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-magnesium-metal.pdf) US Geological Survey, 2026
8. [Mineral Commodity Summaries 2026: Potash](https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-potash.pdf) US Geological Survey, 2026
9. [Several concerns about aqueous zinc metal batteries: from components to unit cells (Li, Liang and Fang, EES Batteries, first published 22 Dec 2025)](https://pubs.rsc.org/en/content/articlehtml/2026/eb/d5eb00159e) Royal Society of Chemistry, 2025
10. [10 years development of potassium-ion batteries (Li, Wang, Wang, Lyu, Wang, Xia, Mao and Guo, Advanced Materials, article 2416717)](https://digital.library.adelaide.edu.au/items/b732b874-d464-475a-ade6-e5af3cb1d53d) Wiley / University of Adelaide repository, 2025
11. [Energizer E91 AA alkaline product datasheet, newer edition (Form EBC-1102Q; undated, hosted on a University of Houston course page)](https://courses.egr.uh.edu/ECE/ECE2100/Archive/Spring%202024%20Honors/E91.pdf) Energizer

## Other sections

- [Summary](https://www.materialinsights.org/energy/e_other_batt/index.md)
- [Overview](https://www.materialinsights.org/energy/e_other_batt/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_other_batt/correlation/index.md)
- [Engineering and performance](https://www.materialinsights.org/energy/e_other_batt/sg-eng/index.md)
- [Economics](https://www.materialinsights.org/energy/e_other_batt/sg-econ/index.md)
- [Impact and additionality](https://www.materialinsights.org/energy/e_other_batt/sg-impact/index.md)
- [What to track](https://www.materialinsights.org/energy/e_other_batt/tracking/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_other_batt/links/index.md)