Are all batteries equally recyclable?

1. Introduction

As we attempt to transition toward a more sustainable society, our demand for batteries is skyrocketing. From consumer devices such as smartphones and laptops to electric vehicles and renewable energy storage systems, batteries are integral to many modern technologies. However, with this surge in battery usage comes the critical issue of their proper disposal and recycling, which are essential for mitigating the environmental impact of batteries and conserving valuable resources.

But are all batteries equally recyclable? This article explores the reasons for recycling batteries, the challenges involved, how batteries are recycled, and the recyclability of different battery types.

2. Why is recycling batteries important?

a. Recycling conserves natural resources and reduces the impact of resource extraction

The materials used to manufacture batteries are finite and costly to extract. Metals such as lithium, cobalt, nickel, manganese, and zinc are essential for battery production, but their extraction is resource-intensive and environmentally damaging. Recycling batteries allows these valuable substances to be recovered and reused, often with a lower economic and environmental cost, reducing the need for new material extraction and conserving natural resources.

b. Batteries contain hazardous materials

Many types of batteries contain hazardous materials that can pose significant environmental and health risks if not properly managed. Toxic elements such as lead, cadmium, and mercury, as well as acids and alkalis, can leach into our soil and water sources, damaging ecosystems and endangering human health. Recycling helps prevent these dangerous substances from entering the environment.

3. Challenges in battery recycling

a. All batteries are not the same

The diverse variety of battery chemistries and designs presents a significant challenge to recycling efforts. Different types of batteries require specifically tailored recycling processes on account of their unique materials and structures. This complexity makes it impossible to implement a one-size-fits-all recycling solution.

b. Technological and economic barriers get in the way

Recycling technologies must continuously evolve to keep pace with the rapid changes in battery technologies. Advanced processing techniques are needed to efficiently and safely recycle different types of batteries. Furthermore, the economic viability of battery recycling is often hindered by high energy and input costs, as well as logistical challenges related to collection, sorting, and transportation.

4. How are batteries recycled?

To understand the differences between different types of batteries when it comes to their recyclability, it is first necessary to consider how batteries are recycled. When a battery reaches the end of its life and is disposed of responsibly, it typically goes through the following series of steps.

a. Collection and sorting

Collection systems: Batteries are collected through various channels, including drop-off points, municipal trash collection, and take-back programs.
Sorting: The collected batteries are automatically or manually sorted by type and chemistry to ensure that they are processed correctly. This is crucial because different batteries require different recycling methods.

b. Mechanical processing

Crushing and shredding: Batteries are often mechanically processed by crushing or shredding to break them down into smaller pieces. This assists with the subsequent separation of the various materials.
Separation techniques: After crushing or shredding, the key materials are separated using one or more physical techniques such as sieving, flotation, magnetic separation, and air classification to isolate the metals, plastics, and other materials. The typical intermediate products at this stage are scrap metal, scrap plastic, and, most importantly in the case of lithium-ion batteries, so-called black mass — a mixture of graphite and the valuable elements such as lithium, cobalt, nickel, and manganese that originally made up the battery active material.

c. Chemical and thermal processing

Pyrometallurgy: This refers to the use of very high temperatures to separate and recover metals via processes such as roasting and smelting. Although pyrometallurgy is well established with a long history, the high temperatures make it energy-intensive and lead to considerable emissions.
Hydrometallurgy: This involves the use of aqueous solutions, such as acids or bases, to leach valuable metals from the recycled battery materials, after which they can be recovered by precipitation or selective extraction and reused. Hydrometallurgical methods are generally regarded as more environmentally friendly on account of their lower energy requirement and emissions.

d. Advanced methods

Direct recycling: This emerging technology aims to directly reuse the components of spent batteries without breaking them down into their constituent materials or altering their structure or morphology, potentially offering higher efficiency and lower environmental impact. One example is froth flotation, which has been successfully applied to separate blended cathode materials used in lithium-ion batteries.
Biohydrometallurgy: This entails the use of biological organisms such as bacteria to recover valuable elements from aqueous waste streams under ambient conditions, minimizing the need for hazardous chemicals and large amounts of heat energy.

5. Main battery types and their recyclability

a. How recyclable are lead–acid batteries?

Lead–acid batteries are widely used as starter batteries in vehicles and in backup power, energy storage, and industrial applications. Despite containing toxic lead and corrosive sulfuric acid, these have the distinction of being highly recyclable. In fact, they are undoubtedly the most recycled type of battery, with recycling rates approaching 99% in some markets. This has been achieved through a combination of strict regulations and economic incentives. The spent lead and plastic parts can be melted and reused, while the sulfuric acid can be either reclaimed or neutralized and safely released.

b. How recyclable are alkaline and zinc–carbon batteries?

In contrast to the other types of batteries discussed here, alkaline and zinc–carbon batteries are both primary (non-rechargeable) batteries — they are intended to be used once and then discarded. Although these are gradually being replaced in some applications by rechargeable alternatives, they are still widely found in remote controls, alarm clocks, toys, and numerous other consumer products and continue to account for a large share of the global battery market.

In many jurisdictions, for example all U.S. states except California, these are permitted to be disposed of with regular household waste. Since the use of mercury in alkaline and zinc–carbon batteries was phased out, these batteries are regarded as less hazardous when sent to landfill. Nonetheless, the safer materials present in these batteries — including nickel-plated steel, manganese dioxide, zinc, plastic, non-woven fabric, and potassium hydroxide — are not entirely innocuous, and the U.S. Environmental Protection Agency still recommends recycling where possible.

One interesting strategy for giving a second life to alkaline battery waste is that developed by Finnish company Tracegrow, which recovers the zinc and manganese to manufacture fertilizers that safely supply these essential micronutrients to plants.

c. How recyclable are nickel–cadmium and nickel–metal hydride batteries?

Nickel–cadmium batteries were at one time the market leader in terms of rechargeable batteries for consumer applications, but concerns over the environmental impact of the heavy metal cadmium have prompted their widespread replacement since the late 1990s. For instance, the 2006 Battery Directive largely restricted consumer sales of nickel–cadmium batteries in the European Union, and the new Batteries Regulation 2023 will further prohibit their use in all portable applications.

Nonetheless, these environmental concerns and regulatory efforts have motivated the development of efficient recycling schemes for the nickel–cadmium batteries that are still in use. According to the International Cadmium Association, over 75% by weight of these batteries can be recycled after collection, and most EU member states met or surpassed this recycling efficiency target in 2021. Most crucially, the toxic cadmium can be conveniently recovered by heating and condensation owing to its relatively high volatility, avoiding contamination of landfills and water sources.

Nickel–metal hydride batteries, one of the safer alternatives developed to replace nickel–cadmium batteries, can also be recycled to recover the valuable nickel and rare-earth elements present within. However, pyrometallurgical processes are energy-intensive while hydrometallurgical methods require large amounts of chemicals, meaning that the cost-effectiveness and overall environmental impact depend on the procedures employed and how efficiently the batteries can be collected, sorted, and processed.

d. How recyclable are lithium-ion batteries?

Despite the prevalence of lithium-ion batteries in modern electronic devices and electric vehicles, the recycling rate of these batteries remains disappointingly low. A widely reported estimate is that only 5% of the world's lithium-ion batteries are recycled. Although the exact figure is controversial and this 5% may be a myth, it is clear that lithium-ion batteries have not yet achieved the recycling rates seen for some other battery types.

Nonetheless, lithium-ion batteries contain multiple valuable elements, including cobalt, nickel, manganese, and of course lithium, all of which are associated with considerable environmental impacts when extracted fresh from the earth and processed into new battery chemicals. With our soaring demand for lithium-ion batteries, these problems can only be expected to become more pressing over the next decade — for instance, the annual worldwide demand for lithium is projected to more than quadruple by 2033 — and the Volta Foundation predicts that recycling will become much more attractive when the first wave of electric vehicles hit their end of life in 2030. If current trends in battery technology continue, it appears inevitable that recycling lithium-ion batteries will become a necessity, especially in light of increasing regulatory pressure.

Although the recycling of lithium-ion batteries is complicated by a diverse array of battery chemistries and designs, efforts are already underway to improve the current recycling rate. Last year saw the announcement of plans to construct new lithium-ion battery recycling plants in Europe, the United States, China, Taiwan, and elsewhere, with a particular focus on large electric vehicle batteries. The new Batteries Regulation 2023 also aims to implement battery passports for larger batteries by 2027 and ultimately create a closed-loop battery value chain in Europe.

6. Conclusion: not all batteries are equally recyclable

As we have explored in this article, not all batteries are equally recyclable. The challenges associated with recycling differ significantly depending on the type of battery and its chemical composition. While some, such as lead–acid batteries, have well-established recycling systems with high recovery rates, others, such as lithium-ion batteries, are still grappling with technological, economic, and logistical hurdles.

The growing demand for batteries, driven by the proliferation of consumer electronics, electric vehicles, and renewable energy storage systems, underscores the urgency of developing better battery recycling technologies. As we look toward the future, the development of more efficient, cost-effective, and eco-friendly recycling strategies will be crucial for mitigating the environmental impact of battery waste and ensuring the sustainable use of our planet's finite resources.

Approaches are already being taken to address these challenges, with new recycling facilities being planned and regulatory frameworks evolving to support a more circular battery economy. However, achieving widespread and efficient battery recycling will require ongoing innovation, collaboration between industry and government, and public participation in responsible disposal practices. The path forward is complex, but with concerted efforts, we can move closer to a future where more batteries are recyclable, minimizing their environmental footprint and contributing to a more sustainable world.

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