Sonochemical Synthesis of Electrode Materials for Battery Production

In the production of high-performance battery cells, nanostructured materials and nanocomposites play an important role providing superior electric conductivity, higher storage densities, high capacity and reliability. In order to attain full functionalities of nanomaterials, nano-particles must be individually dispersed or exfoliated and might need further processing steps such as functionalization. Ultrasonic nano-processing is the superior, efficacious and reliable technique to produce high-performance nanomaterials and nanocomposites for advanced battery production.

Ultrasonic Dispersion of Electrochemically Active Materials in Electrode Slurries

Nanomaterials are used as innovative electrode materials, which resulted in significantly enhanced performance of rechargeable batteries. Overcoming agglomeration, aggregation and phase separation is crucial for the preparation of slurries for electrode manufacturing, especially when nano-sized materials are involved. Nanomaterials increase the active surface area of battery electrodes, which allows them to absorb more energy during charging cycles and to increase their overall energy storage capacity. In order to obtain the full advantage of nanomaterials, these nano-structured particles must be de-entangles and distributes as separate particles in the electrode slurry. Ultrasonic dispersing technology provides focused high-shear (sonomechnical) forces as well as sonochemical energy, which leads to atomic level mixing and complexation of nano-sized materials.
Nano-particles such as graphene, carbon nanotubes (CNTs), metals, and rare earth minerals must be uniformly dispersed into a stable slurry in order to obtain highly functional electrode materials.
For instance, graphene and CNTs are well known to enhance battery cell performance, but particle agglomeration must be overcome. This means, a high-performance dispersion technique, capable to process nanomaterials and possibly high viscosities, is absolutely required. Probe-type ultrasonicators are the high-performance dispersing method, which can process nanomaterials even at high solid loads reliably and efficaciously.

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Ultrasonic nano-sizing and functionalization of particles is an important process in high-performance battery production.

High-power ultrasonic flow-through system for nanomaterial processing. High-performance nanomaterials are used as active electrode materials in battery cells.

Ultrasonic Nanomaterial Processing for Batteries:

  • Dispersion of nanospheres, nanotubes, nanowires, nanorods, nanowhiskers
  • Exfoliation of nanosheets and 2D materials
  • Synthesis of nanocomposites
  • Synthesis of core-shell particles
  • Functionalization of nanoparticles (doped / decorated particles)
  • Nano-structuring

Why is Sonication the Superior Technique for Nanomaterial Processing?

When other dispersing and mixing techniques such as high-shear mixers, bead mills or high-pressure homogenizers come to their limits, ultrasonication is the method which stands out for micron- and nano-particles processing.
High-power ultrasound and the ultrasonically generated acoustic cavitation provide unique energy conditions and extreme energy-density that allows to deagglomerate or exfoliate nanomaterials, to functionalize them, the synthesize nanostructures in bottom-up processes, and to prepare high-performance nanocomposites.
Since Hielscher ultrasonicators allow the precise control of the most important ultrasonic processing parameters such as intensity (Ws/mL), amplitude (µm), temperature (ºC/ºF) and pressure (bar), processing conditions can be individually tuned to optimal settings for each material and process. Thereby, ultrasonic dispersers are highly versatile and can be used for numerous applications e.g., CNT dispersion, graphene exfoliation, sonochemical synthesis of core shell particles or functionalization of silicon nanoparticles.

Sonochemically synthesized Na0.44MnO2 for use as active electrode material in sodium-ion batteries.

SEM micrographs of sonochemically prepared Na0.44MnO2 by calcination at 900°C for 2 h.
(Study and picture: ©Shinde et al., 2019)

Learn more about Hielscher industrial ultrasonicators for nanomaterial processing in battery manufacturing!

Advantages of Ultrasonic Nanomaterial Processing:

  • High-performance, high efficiency
  • Precisely controllable
  • Tuneable to application
  • Industrial grade
  • Linearly scalable
  • Easy, safe operation
  • Cost-efficent

Below you can find various ultrasonically-driven applications of nanomaterial processing:

Ultrasonic Synthesis of Nanocomposites

Ultrasonic synthesis of graphene–SnO2 nanocomposite: The research team of Deosakar et al. (2013) developed an ultrasonically-assisted route to prepare a graphene–SnO2 nanocomposite. They investigated the cavitational effects generated by high-power ultrasound during the synthesis of graphene–SnO2 composite. For sonication, they used a Hielscher Ultrasonics device. The results demonstrate an ultrasonically improved fine and uniform loading of SnO2 on graphene nanosheets by oxidation–reduction reaction between graphene oxide and SnCl2·2H2O compared to conventional synthesis methods.

Sonochemically synthesized SnO2-nanocomposite can be used as anode material in batteries.

Chart demonstrating the formation process of graphene oxide and SnO2–graphene nanocomposite.
(Study and pictures: ©Deosakar et al., 2013)

SnO2–graphene nanocomposite has been successfully prepared through a novel and effective ultrasound assisted solution-based chemical synthesis route and graphene oxide was reduced by SnCl2 to graphene sheets in the presence of HCl. TEM analysis shows the uniform and fine loading of SnO2 in graphene nanosheets. The cavitational effects produced due to the use of ultrasonic irradiations have been shown to intensify the fine and uniform loading of SnO2 on graphene nanosheets during oxidation–reduction reaction between graphene oxide and SnCl2·2H2O. The intensified fine and uniform loading of SnO2 nanoparticles (3–5 nm) on reduced graphene nanosheets is attributed to the enhanced nucleation and solute transfer due to cavitational effect induced by ultrasonic irradiations. Fine and uniform loading of SnO2 nanoparticles on graphene nanosheets was also confirmed from TEM analysis. The application of synthesized SnO2–graphene nanocomposite as an anode material in lithium ion batteries is demonstrated. The capacity of SnO2–graphene nanocomposite based Li-battery is stable for around 120 cycles, and the battery could repeat stable charge–discharge reaction. (Deosakar et al., 2013)

Ultrasonic synthesis allows to manufacture high-performance nanocomposites used in battery manufacturing.

TEM image of SnO2–graphene nano-composite prepared by sonochemical method. Bar indicates at (A) 10nm , at (B) at 5nm.
(Study and pictures: ©Deosakar et al., 2013)

High-intensity ultrasonication is an essential technique in nanomaterial synthesis and functionalization. Industrial ultrasonic systems are capable to process very large volumes.

Industrial mixing system with 4x 4000 watts ultrasonicators of the model UIP4000hdT for nanomaterial processing of electrode compounds.

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Ultrasonic Dispersion of Nanoparticles into Battery Slurries

Dispersion of electode components: Waser et al. (2011) prepared electrodes with lithium iron phosphate (LiFePO4). The slurry contained LiFePO4 as active material, carbon black as an electrically conductive additive, polyvinylidene fluoride dissolved in N-methylpyrrolidinone (NMP) was used as a binder. The mass-ratio (after drying) of AM/CB/PVDF in the electrodes was 83/8.5/8.5. To prepare the suspensions, all electrode constituents were mixed in NMP with an ultrasonic stirrer (UP200H, Hielscher Ultrasonics) for 2 min at 200 W and 24 kHz.
Low electric conductivity and slow Li-ion diffusion along the one-dimensional channels of LiFePO4 can be overcome by embedding LiFePO4 in a conductive matrix, e.g. carbon black. As nano-sized particles and core-shell particle structures improve electrical conductivity, ultrasonic dispersion technology and sonochemical synthesis of core-shell particles allow to produce superior nanocomposites for battery applications.

Dispersion of lithium iron phosphate: The research team of Hagberg (Hagberg et al., 2018) used the ultrasonicator UP100H for the procedure of structural positive electrode consisting of lithium iron phosphate (LFP) coated carbon fibers. The carbon fibers are continuous, self-standing tows acting as current collectors and will provide mechanical stiffness and strength. For optimal performance, the fibers are coated individually, e.g. using electrophoretic deposition.
Different weight ratios of mixtures consisting of LFP, CB and PVDF were tested. These mixtures were coated onto carbon fibers. Since inhomogeneous distribution in the coating bath compositions might differ from the composition in the coating itself, rigorous stirring by ultrasonication is used to minimize the difference.
They noted that the particles are relatively well dispersed throughout the coating which is attributed to the use of surfactant (Triton X-100) and the ultrasonication step prior to electrophoretic deposition.

Ultrasonic dispersion is used to homogenize LFP, CB and PVDF before electrophoretic deposition.

Cross-section and high magnification SEM images of EPD coated carbon fibres. The mixture of LFP, CB and PVDF was ultrasonically homogenized using the ultrasonicator UP100H. Magnifications: a) 0.8kx, b) 0.8kx, c) 1.5kx, d) 30kx.
(Study and picture: ©Hagberg et al., 2018)

Dispersion of LiNi0.5Mn1.5O4 composite cathode material:
Vidal et al. (2013) investigated the influence of processing steps such as sonication, pressure and material composition for LiNi0.5Mn1.5O4composite cathodes.
Positive composite electrodes having LiNi0.5 Mn1.5O4 spinel as active material, a blend of graphite and carbon black for increasing the electrode electrical conductivity and either polyvinyldenefluoride (PVDF) or a blend of PVDF with a small amount of Teflon® (1 wt%) for building up the electrode. They have been processed by tape casting on an aluminum foil as current collector using the doctor blade technique. Additionally, the component blends were either sonicated or not, and the processed electrodes were compacted or not under subsequent cold pressing. Two formulations have been tested:
A-Formulation (without Teflon®): 78 wt% LiNi0.5 Mn1.5O4; 7.5 wt% Carbon black; 2.5 wt% Graphite; 12 wt% PVDF
B-Formulation (with Teflon®): 78wt% LiNi00.5Mn1.5O4; 7.5wt% Carbon black; 2.5 wt% Graphite; 11 wt% PVDF; 1 wt% Teflon®
In both cases, the components were mixed and dispersed in N-methylpyrrolidinone (NMP). LiNi0.5 Mn1.5O4 spinel (2g) together with the other components in the mentioned percentages already set up was dispersed in 11 ml of NMP. In some particular cases, the mixture was sonicated for 25 min and then stirred at room temperature for 48 h. In some others, the mixture was just stirred at room temperature for 48 h, i.e. without any sonication. The sonication treatment promotes a homogeneous dispersion of the electrode components and the LNMS-electrode obtained looks more uniform.
Composites electrodes with high weight, up to 17mg/cm2, were prepared and studied as positive electrodes for lithium-ion batteries. The addition of Teflon® and the application of the sonication treatment lead to uniform electrodes that are well-adhered to the aluminum foil. Both parameters contribute to improve the capacity drained at high rates (5C). Additional compaction of the electrode/aluminum assemblies remarkably enhances the electrode rate capabilities. At 5C rate, remarkable capacity retentions between 80% and 90% are found for electrodes with weights in the range 3-17mg/cm2, having Teflon® in their formulation, prepared after sonication of their component blends and compacted under 2 tonnes/cm2.
In summary, electrodes having 1 wt% Teflon® in their formulation, their component blends subjected to a sonication treatment, compacted at 2 tonnes/cm2 and with weights in the range 2.7-17 mg/cm2 showed a remarkable rate capability. Even at the high current of 5C, the normalized discharge capacity was between 80% and 90% for all these electrodes. (cf. Vidal et al., 2013)

The UIP100hdT is a 1kW bench-top ultrasonicator for industrial nanomaterial processing in batch or flow-through mode.

Ultrasonicator UIP1000hdT (1000W, 20kHz) for nanomaterial processing in batch or flow-through mode.

High-Performance Ultrasonic Dispersers for Battery Production

Hielscher Ultrasonics designs, manufactures and distributes high-power, high-performance ultrasonic equipment, which is used to process cathode, anode, and electrolyte materials for use in lithium-ion batteries (LIB), sodium-ion batteries (NIB), and other battery cells. Hielscher ultrasonic systems are used synthesize nanocomposites, functionalize nanoparticles, and disperse nanomaterials into homogeneous, stable suspensions.
Offering a portfolio from lab to fully-industrial scale ultrasonic processors, Hielscher is the market leader for high-performance ultrasound dispersers. Working since more than 30 years in the field of nanomaterial synthesis and size reduction, Hielscher Ultrasonics has extensive experience in ultrasonic nanoparticle processing and offers the most powerful and reliable ultrasonic processors on the market. German engineering provides state-of-the-art technology and robust quality.
Hielscher ultrasonicators can be remotely controlled via browser control. Sonication parameters can be monitored and adjusted precisely to the process requirements.Advanced technology, high-performance and sophisticated software turn Hielscher ultrasonicators into reliable work horses in your electrode manufacturing process. All ultrasonic systems are manufactured in the headquarter in Teltow, Germany, tested for quality and robustness and are then distributed from Germany all around the world.
The sophisticated hardware and smart software of Hielscher ultrasonicators are designed to guarantee reliable operation, reproducible outcomes as well as user-friendliness. The Hielscher ultrasonicators are robust and consistent in performance, which allows to install them into demanding environments and to operate them under heavy duty conditions. Operational settings can be easily accessed and dialled via intuitive menu, which can be accessed via digital colour touch-display and browser remote control. Therefore, all processing conditions such as net energy, total energy, amplitude, time, pressure and temperature are automatically recorded on a built-in SD-card. This allows you to revise and compare previous sonication runs and to optimize the synthesis, functionalization, and dispersion of nanomaterials and composites to highest efficiency.
Hielscher Ultrasonics systems are used worldwide for sonochemical synthesis of nanomaterials and are proven to be reliable for the dispersion of nanoparticles into stable colloidal suspensions. Hielscher industrial ultrasonicators can continuously run high amplitudes and are built for 24/7 operation. Amplitudes of up to 200µm can be easily continuously generated with standard sonotrodes (ultrasonic probes / horns). For even higher amplitudes, customized ultrasonic sonotrodes are available.
Hielscher ultrasonic processors for sonochemical synthesis, functionalization, nano-structuring and deagglomeration are already installed worldwide on commercial scale. Contact us now to discuss your process step involving nanomaterials for battery manufacturing! Our well-experienced staff will be glad to share more information about superior dispersion results, high-performance ultrasonic systems and pricing!
With the advantage of the ultrasonication, your advanced electrode and electrolyte production will excel in efficiency, simplicity and low cost when compared to other electrode manufacturers!

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

Batch Volume Flow Rate Recommended Devices
1 to 500mL 10 to 200mL/min UP100H
10 to 2000mL 20 to 400mL/min UP200Ht, UP400St
0.1 to 20L 0.2 to 4L/min UIP2000hdT
10 to 100L 2 to 10L/min UIP4000hdT
n.a. 10 to 100L/min UIP16000
n.a. larger cluster of UIP16000

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Ultrasonic high-shear homogenizers are used in lab, bench-top, pilot and industrial processing.

Hielscher Ultrasonics manufactures high-performance ultrasonic homogenizers for mixing applications, dispersion, emulsification and extraction on lab, pilot and industrial scale.

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High performance ultrasonics! Hielscher's product range covers the full spectrum from the compact lab ultrasonicator over bench-top units to full-industrial ultrasonic systems.

Hielscher Ultrasonics manufactures high-performance ultrasonic homogenizers from lab to industrial size.