Say Hi to Ziggy, the Biodegradable Battery

Imagine a hardworking biodegradable battery powering a temporary soil sensor in the field, a tool measuring soil conditions to guide the frequency of watering and fertilizing. After days or weeks, its job of supplying power is done. Instead of needing to retrieve it or leaving electronic waste in the fields, the battery simply dissolves.

The idea sounds perfect: use the battery, then let nature take care of it. But reality is more complicated. Vanishing does not always mean harmless, and even the most eco-friendly inventions can carry hidden burdens.

Decomposing Biodegradable Batteries

Compostable batteries are energy storage devices designed to break down under controlled composting conditions, often at 58 °C (136.4 °F), 50% humidity, and pH of 6.5 to 8. They can be born in two ways. Some are designed to disappear almost entirely, built with a 3D printer using all-degradable polymers. Others are partially biodegradable: their binders, packaging, and separators can compost away, while metals inside slowly dissolve rather than fully biodegrade. The battery we’ll focus on if of the second type.

To be more precise, it is part of the aqueous zinc-ion family (AZIB), specifically the manganese dioxide branch (Zn-MnO2), which we will call Ziggy for its compounds. The key distinction of aqueous batteries is that they are water-based, making them chemically milder and safer than batteries based on organic solvents such as ethylene carbonate and polycarbonate. While not all AZIBs are biodegradable, versions like our Ziggy can be engineered to be so by replacing the un-chargable components that hold the battery together with compostable materials.

The Birth of a Battery

Right at birth, our young battery faces competition from powerful cousins, especially lithium-ion (Li-ion) batteries, one of the most popular conventional battery types used today.

In manufacturing, AZIBs like Ziggy perform surprisingly well. Studies suggest that producing various AZIBs can on average result in 45.1 kilograms of CO2 per watt-hour, nearly half the greenhouse gasses emissions of Li-ion batteries at 39 to 196 kilograms of CO2 per watt-hour. For clarity, producing 39 kilograms of CO2 per one kilowatt-hour battery is like driving an average car for 96.5 miles to power an average microwave for an hour. Regarding other factors, all tested AZIB types score better for terrestrial acidity and cancerogenic human toxicity, although non-cancerogenic human toxicity for AZIBs was higher for all material types. 

But there is no rest for Ziggy, as another competitor enters the scene: the all-organic polymer battery. Ironically, producing some all-organic batteries has, so far, shown greater greenhouse gasses emissions, ozone depletion, and toxicity than the production of Li-ion batteries and AZIBs. This is because all-polymer components are not as effective for energy storage as metals are. The specific energy (or how much energy it provides compared to its total mass) of all-organic batteries is five times lower than that of Li-ion ones and nearly seven times lower than some successfully optimized zinc and manganese dioxide based AZIBs. Due to this, a lot more material needs to be created to achieve the same output, leading to higher environmental impacts.

This does not prove that all-organic batteries are a bad idea, but it does show that when specific energy is low, manufacturing demands might complicate the end-of-life environmental benefits.

Overall, with the limited all-organic battery manufacturing data available, Ziggy seems to win in the production effects. However, our battery’s story is still unfolding.

Entering the Workforce

Soon after manufacturing, Ziggy is deployed where it is needed: networks of connected data-exchanging devices, eco-friendly sensors, and data-secure electronics. 

Here it competes again with lithium-ion batteries, whose main strength is that they deliver high energy density of 100–265 watt-hours per kilogram of material. However, Ziggy meets the challenge admirably, its power output matching that of Li-ion batteries at 150 watt-hours per kilogram with the newest advances in design. Additionally, like Li-ion, some Zn-MnO2 based AZIBs like Ziggy can be recharged, and considering our battery doesn’t need to be recovered when used in hard-to-retrieve agricultural monitoring devices, it does its job better in some scenarios than its Li-ion relative.

Meanwhile, another contender enters the field, though not for long, as its defeat is nigh: the all-organic batteries. They are, as mentioned above, seven times weaker per kilogram of substance than most advanced Ziggies. This makes all-organic batteries bulkier and less efficient.

In this regard, our battery is doing a good job at matching and even outperforming its competition, however, there are still the post-mortem costs to consider.

End of Life

When our hero’s job is done, its body starts its return to the earth. However, letting it decompose in one place without recovering active components, elements that hold the energy inside the battery, can lead to them accumulating and exceeding safe values by as much as 180 times for zinc and eight times for chlorides. This can cause soil quality to degrade and plants to die, leading researchers to suggest that better composting standards for these batteries be developed.

This challenges the comforting assumption that biodegradable batteries automatically solve the battery disposal problem. Batteries like our hero may reduce persistent plastics and certain toxic components, but they can still introduce harmful substances into the environment if handled improperly.

But how does this compare to the other contestants?

Li-ion batteries create a different end-of-life problem: when they are discarded as waste, they can become a serious chemical hazard. Lithium-ion cells contain limited and toxic materials such as lithium, cobalt, nickel, manganese, and electrolyte salts. These can pose threat to soil, air, and water safety, as well as deplete ozone layer and increase cancer and respiratory disorder risks in humans if released.

Due to the lack of enforcement, these batteries are most often tossed or incinerated, which introduces harmful compounds into the air, water, and soil. The best disposal method for them is recycling, which while not being entirely pollution-free, minimizes negative effects on nature. However, the recovery rate for Li-ion battery materials is low, with less than 40% of a battery being recyclable with the current technology and operation patterns.

As for the last contestant, the costs of all-organic battery dissolution is currently undetermined. Researchers, however, are optimistic, citing metals such as zinc, manganese, and chlorides, as the main problem with biodegradable batteries, and saying that replacing them with all-organic polymer might result in a technology that is safe to compost.

The Moral of the Story

If biodegradable batteries like Ziggy are to become more common, their story needs careful editing.

Their dissolution time should be tightly controlled so the batteries remain stable while they work and release predictable doses of ions afterwards. Regulations, composting standards, and environmental testing must grow alongside innovation. Ziggy is a step in the right direction, but its power needs to be handled responsibly if it enters a large-scale production.

The story also reminds us that labels like “biodegradable” or “eco-friendly” deserve closer inspection. Sometimes they could be pure marketing, like we so often see with food items in grocery stores, while other times, they signal a genuinely promising approach, especially when the claim is backed by real toxicity data. This is why climate education matters, as it helps us connect everyday technology to real-world environmental outcomes. As such, we encourage you to sign the Pledge to Support Climate and Environmental Literacy to ensure that future generations have the tools they need to navigate the complex landscape of green labels and real impacts.

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