Battery packs come in different sizes, shapes, and chemistries. You can find them everywhere, from your smartphones, laptops, drones, toys, TV remote controls to all household electronic appliances and devices.
What happens to a battery when it is spent? Usually, people throw them away. But do you know that spent batteries should be removed from the household because they are environmentally unfriendly and can cause damage to the surrounding environment if disposed of with other waste?
Batteries pose the largest environmental concerns because the leaking materials like lead and sulphuric acid can contaminate the water, soil, and some of the elements can accumulate in wildlife and humans. Most of the time, these hazardous materials enter landfills, resulting in pollution caused by valuable chemical components such as cobalt, copper, lithium, a mixture of organic electrolytes and salts of either low quality or spent lithium-ion batteries (LiBs).
Proper disposal of batteries is critical. Several companies are finding ways to commercialize recycling batteries on an industrial scale to minimize environmental toxicity and sustain natural resources by utilizing the reusable materials in the fabrication of new products.
More than 97% of these batteries are recycled in the USA today. Over 50% of the lead supply comes from recycled batteries, and 20 to 40% of batteries in mobile phones and other household products are recycled.
Recycling constitutes the most generally acceptable environmentally friendly methods of ensuring a high recovery of the scarce materials and proper management of any dangerous components. Each battery pack undergoing recycling goes through a series of steps where it is transformed and broken down into simpler components.
A series of physical preparatory steps usually involve sorting batteries by chemistry type, dismantling the battery pack to a module or cell level, which could then be directly fed into the recycling scheme or further fragmented by shredding or grinding.
Each recycler may use a variation or combination of steps in the recycling processes (schemes), which can be broadly classified as Pyrometallurgical recycling, Hydrometallurgical recycling, Mechanical or physical recycling.
- Pyrometallurgical recycling involves the use of heat to recover metallic battery components.
- Hydrometallurgical recycling consists of a series of chemical steps with aqueous solutions for the recovery of metals from the battery powder.
- Mechanical or physical recycling relies on the mechanical and physical separation of battery components.
1. Pyrometallurgical recycling
Pyrometallurgical recycling (smelting) uses high-temperature furnaces to burn large quantities of battery packs and combustible battery materials (e.g., graphite anode, aluminum wires, paper, and plastic casing). The process reduces the chemical components (e.g., copper, cobalt, nickel, iron) into molten metals, which are collected as alloys to be sent to metal refineries for further processing and recycling.
It recovers valuable transition metals but leaves behind a furnace slag, consisting of ashes of the burnt components and primarily containing lithium, aluminum, silicon, calcium, and some iron compounds. Since it is uneconomical to recover individual components from the slag, some recyclers sell or reuse the slag (rich in structural oxides) as a cement additive, whilst others submit the slag to further recovery steps using hydrometallurgy. The key advantage of pyrometallurgical recycling is that all battery chemistries can be recycled simultaneously.
Pros
- Flexible process input – Applicable to any battery chemistry, battery types, and configuration.
- No sorting or size reduction – No mechanical pre-treatment is needed. For consumer electronics batteries, whole packs can be treated.
- High recovery of metals
- Higher profit from the recovery of Co, Ni, Cu.
- No SOx emission from metal production
- Commercially viable
Cons
- Gas clean-up is essential to avoid toxic air emissions
- Energy-intensive and expensive gas treatment.
- Li and Al go to slag
- Further refining is necessary to separate elemental metals from the metal alloys.
- Capital intensive and requires a high volume
- Not useful for LFP
2. Hydrometallurgical recycling
Hydrometallurgical recycling (leaching) uses acids to dissolve the metal components of batteries, primarily found in the cathode of LIBs. To facilitate dissolution, battery packs are dismantled, and cells are usually further fragmented by crushing and shredding. Once the metals are brought into solution, depending on the recycling facility, several solvent extractions, chemical precipitation, and electrolysis steps may be required to separate the constituent elements as inorganic salts.
The copper and aluminum foils are easy to recover as pure metals, although they must be separated from each other. This process is especially attractive for LFP and LMO cathodes, being the only method devised so far to recover any significant value from them. It can also recover electrolyte and anode materials.
Pros
- Highly economical and doesn’t require large investments.
- Low temperature and low energy
- Higher recovery rate
- Applicable to any battery chemistry and configuration
- Flexibility in separation and recovery processes to target specific metals
- High purity of products. Substrate foils recovered directly.
- Output can be converted to cathode precursors
- Energy-efficient in comparison to pyrometallurgy
- No air emissions
Cons
- Recycling needs optimization for certain battery chemistry to ensure high recovery and profit.
- Requires size reduction.
- Acid breaks down cathode structure
- No valuable product from LFP
- Solvent extraction needed to separate Co and Ni
- A high volume of process effluents should be treated and recycled or disposed of.
3. Physical/mechanical recycling
Physical or mechanical recycling consists of manual or automated dismantling and crushing of the battery packs to recover key components in their original state (e.g., electrodes, wiring, casing). Some recovered components (e.g., electrodes) could be used directly in the manufacturing of new batteries, whilst other components (e.g., wiring) need recycling using usual pyro or hydro schemes (as metals). The process allows components to be reused in new batteries immediately without much additional processing.
Pros
- Almost all battery materials can be recovered
- Retains valuable cathode structure
- Can recover anode, electrolyte, and foils
- Can be used for LFP
- Used for prompt scarp and low volumes
- Low temperature and energy
- Avoids most impacts on virgin material production
Cons
- Mechanical pre-treatment and separations required
- Recovered material may not perform as well as virgin material
- Mixing cathode materials could reduce the value of the recycled product
- Requires single-cathode input
- May recover obsolete formulation
- Degradation may limit repeats
- Buyers must be assured of quality
- Not demonstrated at scale.
