Ultrasonics Makes Lithium-Ion Battery Recycling More Efficient

Lithium is a scarce and highly valuable material present in high-performance batteries, such as Li-ion batteries. Lithium is the most valuable material that is recovered in Li-ion battery recycling, but also other minerals and metals such as cobalt, manganese, nickel, copper and aluminum are valuable metals for recovery. High-intensity ultrasonication is used as high-shear agitation and leaching technique to extract, remove, and dissolve valuable minerals and metals from spent batteries. The sonication method is highly efficacious, energy-efficient, and is readily available for installation in full-commercial recycling facilities.

Overview: Li-Ion-Battery Recycling Process

The recycling process of precious metals and materials from spent Li-ion batteries typically involves several steps. Here’s a general overview:

1. Collection and sorting: Spent Li-ion batteries are collected and sorted based on their types and chemistries.
2. Disassembly: First, the plastic cover of the battery is broken up and removed.Afterwards, the naked battery is put in liquid nitrogen in order to neutralise reactive, explosive substances. This step makes sure that a sudden release of all stored energy and the subsequent ignition and explosion associated with are prevented. Then, the batteries are disassembled to separate the different components, such as the cathode, anode, electrolyte, and casing.
3. Shredding: The disassembled batteries are shredded into smaller pieces to increase the surface area for subsequent processes.
4. Electrode delamination: Before the metal-extraction treatment, the isolated electrodes, i.e. cathode and anode, must be further disassembled. Since the cathode material is generally adhered to aluminum foil by a binder, commonly polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE), it is a difficult task to remove cathode and aluminum foil from each other.
5. Chemical treatment: The shredded battery components undergo various chemical treatments to dissolve and separate the different materials. This may involve leaching with acid or other solvents to extract valuable metals like lithium, cobalt, nickel, and copper.
6. Recovery and purification: The dissolved metals are then recovered from the solution through processes like precipitation, solvent extraction, or electrochemical methods. These steps help purify and concentrate the precious metals.

Precious Metal Recovery Improved by Sonication

Power ultrasound can enhance the steps of electrode delamination and leaching of precious metals and materials by intensifying the reactions thereby making the recovery process significantly more efficient. Ultrasonication, it is a technique that utilizes high-intensity ultrasound waves to create mechanical vibrations and acoustic cavitation in a liquid medium. The strong forces of ultrasonication are used to enhance the recycling process of precious metals from spent Li-ion batteries in several ways:
 

1. Disintegration: Ultrasonication breaks down the shredded battery materials so that smaller particles are created. Smaller particles offer a higher surface area which makes the chemical leaching more effectively, aiding in the liberation of valuable metals.
2. Improved leaching: The application of ultrasonication during leaching processes can enhance the contact between the solid material and the leaching solution, increasing the efficiency of metal extraction. Ultrasonic leaching promotes the metal extraction and increases the yield of recovered of metals and minerals such as cobalt, manganese, nickel, copper and aluminum.
3. Improved electrode delamination: The goal of electrode delamination during battery recycling is to separate the different components, such as electrodes, electrolytes, and separators, so they can be further processed or recycled individually. Ultrasonication assists the detachment and removal of coatings from the electrode. Sonomechanical forces promote the efficient separation of the layers of the electrodes.
4. Accelerated reactions: Ultrasonication promotes faster and more thorough mixing, which can accelerate chemical reactions during metal recovery and purification steps.
5. Reduced energy consumption: Ultrasonication can enhance process efficiency, reducing the time and energy required for metal recovery from spent batteries.

 
Ultrasonication can play a beneficial role in improving the recycling process of precious metals and materials from spent Li-ion batteries by increasing the effectiveness and efficiency of various steps involved in the recycling process.
The process steps of ultrasonic metal leaching and electrode delamination can be adapted to individual recycling processes, which can vary as companies specialising in Li-ion battery recycling develop and modify their processes to highest efficiency.

Ultrasonic Cavitation for Cathode Separation

Ultrasonication separates cathode materials from aluminum foil by the effects of acoustic cavitation. Acoustic or ultrasonic cavitation is determined by locally occurring high pressures, high temperatures and their subsequent drops resulting in respective pressure and temperature differentials as well as intense micro-turbulences and high-shear micro-jets. These cavitational forces affect surface boundaries, promote mass transfer and cause erosion. Generating such intense forces of chemical, physical, thermal and mechanical nature, ultrasonic cavitation creates the required agitation and mass transfer to break the organic binder structure used in lithium-ion batteries to fixate the cathode to the collector / aluminum foil.
Whilst mechanical agitation such as stirring alone is insufficient to detach the cathode material effectively from the aluminum foil, high-intensity ultrasonication provides the required sonochemical and sonomechanical energy to remove the cathode material completely from the collectors. In contrast to mechanical stirring, ultrasonic cavitation generates intense turbulences, locally high temperatures and pressures as well as agitation, streaming and liquid jets, which break up the binder, e.g. PVDF or PTFE, which connect the cathode to the Al foil, and erodes the surface of both, cathode and Al foil. Thereby, the binder between both materials is properly destructed and cathode and aluminum foil are effectively separated.
For instance, ultrasonic separation results in high efficiency of the cathode removal of 99% using N-methyl-2-pyrrolidone (NMP) as solvent at 70°C (240 W ultrasonic power, and 90 min ultrasonic processing time). Since ultrasonic cathode separation disperses the material evenly and prevents larger agglomerates, the subsequent metal leaching process is facilitated.
Read more about ultrasonic electrode delamination in order to recover active materials and current collector foils!

Ultrasonic Leaching of Minerals

The ultrasonic cavitational effects described above promote the leaching of metals from spent batteries, too. High-intensity ultrasonication is not only used to recover mineral in battery recycling, but is also often used in hydrometallurgy and the leaching of precious ores (e.g. mining tailings). The high localized temperatures, pressures, and shear forces intensify the metal leaching and increase leaching efficiency significantly. Whilst in the cavitational hot-spots occur localized very extreme temperatures of up to 1000 K, the overall leaching conditions require only mild temperature of approx. 50-60°C. This makes the ultrasonic metal recovery energy efficient and economical.
Ultrasonic leaching of minerals from spent Li-ion batteries is characterized by high recovery rates and efficiency. For instance, sulfuric acid (H2SO4) was successfully used as leaching agent in the presence of hydrogen peroxide (H2O2) during ultrasonic mineral recovery from the cathode. Ultrasonic leaching with sulfuric acid resulted in recovery rates of 94.63% for cobalt, and 98.62% for lithium, respectively.
Ultrasonic leaching with organic citric acid (C6H8O7·H2O) results in very high recoveries of copper and lithium, obtaining 96% copper and nearly 100% lithium from the spent Li-ion batteries.

Simple and Safe: Ultrasonic Scale-up From Feasibility Tests to Industrial Recycling

High-performance ultrasonic equipment for Li-ion battery recycling is readily available for bench-top, pilot and industrial installation. Since ultrasonic cathode separation and ultrasonic leaching of minerals from spent batteries are already established processes, the process from first trials, optimisation to your specific process requirements and installation of a fully-industrial ultrasonic separation and/or leaching system is quick and simple.

High Performance Ultrasonicators For Battery Recycling

Hielscher Ultrasonics supplies high-performance ultrasonicators at any size and capacity. With the UIP16000 (16kW), Hielscher manufactures the most powerful ultrasonic processor worldwide. The UIP16000 as well as all other industrial ultrasonic systems can be easily clusters to the required processing capacity. All Hielscher ultrasonicators are built for 24/7 operation under full load and in demanding environments.
Hielscher Ultrasonics’ industrial ultrasonic processors can deliver very high amplitudes. Amplitudes of up to 200µm can be easily continuously run in 24/7 operation. For even higher amplitudes, customized ultrasonic sonotrodes are available.

Ultrasonic Probes and Sono-Reactors for Any Volume

Hielscher Ultrasonics product range covers the full spectrum of ultrasonic processors from compact lab ultrasonicators over bench-top and pilot systems to fully-industrial ultrasonic processors with the capacity to process truckloads per hour. The full product range allows us to offer you the most suitable ultrasonic equipment for your application, process capacity and production targets.

Precisely Controllable Amplitudes for Optimum Results

All Hielscher ultrasonic processors are precisely controllable and thereby reliable work horses in R&D and production. The amplitude is one of the crucial process parameters that influence the efficiency and effectiveness of sonochemically and sonomechanically induced reactions. All Hielscher Ultrasonics’ processors allow for the precise setting of the amplitude. Sonotrodes and booster horns are accessories that allow to modify the amplitude in an even wider range. Hielscher’s industrial ultrasonic processors can deliver very high amplitudes and deliver the required ultrasonic intensity for demanding applications. Amplitudes of up to 200µm can be easily continuously run in 24/7 operation.
Precise amplitude settings and the permanent monitoring of the ultrasonic process parameters via smart software give you the possibility to separate cathode from the aluminum foil as well as to leach minerals and metals from spent Li-ion batteries under the most effective ultrasonic conditions. Optimal sonication for most efficient Li-ion battery recycling!
The robustness of Hielscher’s ultrasonic equipment allows for 24/7 operation at heavy duty and in demanding environments. This makes Hielscher’s ultrasonic equipment a reliable work tool that fulfils your recycling process requirements.

Highest Quality – Designed and Manufactured in Germany

As a family-owned and family-run business, Hielscher prioritizes highest quality standards for its ultrasonic processors. All ultrasonicators are designed, manufactured and thoroughly tested in our headquarter in Teltow near Berlin, Germany. Robustness and reliability of Hielscher’s ultrasonic equipment make it a work horse in your production. 24/7 operation under full load and in demanding environments is a natural characteristic of Hielscher’s high-performance ultrasonic probes and reactors.

The table below gives you an indication of the approximate processing capacity of our ultrasonicators: