Dry-Electrode Manufacturing for High-Energy Lithium-Ion Batteries: Principles, Advances, and Challenges

Figure 1 compares a conventional battery-manufacturing process (wet) with a dry process. Wet processing involves dispersing active materials, conductive additives, and polymer binders into an organic solvent (e.g., NMP). This mixture forms a homogeneous slurry, which is coated onto metallic current collectors—commonly aluminum for cathodes and copper for anodes. After coating, the electrodes undergo drying to evaporate the solvent, followed by calendering to adjust thickness and enhance mechanical integrity. Slitting tailors the electrode dimensions, and final vacuum drying completes the fabrication process.

Fig. 1. Schematic of the wet processing and dry processing methods for electrode fabrication.

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Because NMP is toxic, an extensive solvent-recovery system is necessary to reduce environmental and health risks.^21,22 Furthermore, coating, drying, and solvent-recovery steps represent roughly half of the total energy consumption in electrode fabrication, contributing to high costs and increased carbon emissions.^23-25 Wet processing also struggles with thick-electrode manufacturing: during drying, the electrode can shrink and crack, yielding poor mechanical properties and uneven material distribution. These defects degrade electrochemical performance and limit the scalability of high-energy-density LIBs.^15,16,26

Dry-electrode manufacturing eliminates solvent use entirely. This solvent-free approach mixes active materials, conductive additives, and binders in solid-state form, followed by dry-coating or pressing methods to form electrodes. By removing the need for energy-intensive drying and solvent recovery, dry-electrode technology lowers energy consumption and operational costs.^27-29

A chief advantage of dry processing is the ability to circumvent the shrinkage and cracking issues in thick electrodes. With no solvent to evaporate, the electrode structure remains more stable, and mechanical integrity is improved, particularly important for high-energy-density applications.^14,15,30,31 In addition, PTFE serves as a solvent-free binder, thus avoiding the toxicity associated with NMP while simplifying manufacturing complexity and reducing costs.^26,28 Dry-electrode production therefore emerges as a scalable, cost-effective, and eco-friendly innovation that helps meet global sustainability targets.

Electrostatic-spray deposition relies on electrostatic forces to coat current collectors with charged, dry-powder particles composed of active materials, conductive additives, and binders. The grounded substrate attracts these particles, which form a uniform layer without using solvents— substantially lowering energy consumption and production costs. Precise control over thickness and material distribution is another benefit. Compared to conventional wet coating, electrostatic-spray deposition often requires less binder and fewer conductive additives while maintaining comparable electrochemical performance.^27,32,33 For example, Pan et al. demonstrated an LCO electrode fabricated via electrostatic spraying that achieved 77% capacity retention after 100 cycles at 0.3C, using only 1 wt% total binder and conductive additives.²⁷ However, scaling up remains challenging: ensuring uniform powder deposition, precise thickness control, and integration into existing manufacturing lines must be addressed for large-scale adoption.

Fig. 2. Schematic of the electrostatic spray deposition (ESD) process for dry electrode fabrication, illustrating powder atomization, deposition onto an Al foil substrate, and subsequent calendering for densification.³²

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Pressing-based fabrication produces electrodes by compressing dry powders under high temperature and pressure. This approach triggers phase transitions in polymers, enabling the formation of thick films with high-energy density. Typically, the dry-powder mixture—consisting of active materials, conductive additives, and binder—is first heated and then compressed to form a dense film.^8,34 Park et al. showed that pressing-based NCM712 electrodes achieved an area capacity of 17.6 mAh/cm², demonstrating the method’s promise.⁸ Advantages include precise control over temperature and pressure, which broadens binder compatibility and speeds production. However, industrial scaling poses challenges: pressing can demand high pressures, and designs remain polymer-dependent. Material homogeneity and particle-size distribution also require careful management to ensure consistent electrochemical performance.

Extrusion adapts injection-molding concepts to dry-elect-rode manufacturing. Active materials, conductive additives, and binders are mixed and heated to form a continuous film, with thermoplastic polymers facilitating uniform blending.³⁶ Passerini et al. demonstrated extrusion-based fabrication of LTO and LFO cathodes, achieving area capacities over 13 mAh/cm².³⁷ Further steps such as calendering, lamination, debinding, and sintering produce a porous structure that enhances electrochemical performance. Extrusion supports high-energy-density electrodes for materials like LFP, LTO, and NCM. Nevertheless, it often demands higher binder usage, longer processing times, and post-processing at elevated temperatures, all of which can slow commercialization.^35-37 Precise control over particle size, temperature, and residence time is also critical to avoid nonuniform distribution and to preserve optimal electrochemical properties. Even so, extrusion enables the construction of tailored electrode architectures with controlled porosity, making it a noteworthy candidate for future dry-electrode technologies.

Fig. 3. Schematic of the pressing-based dry electrode fabrication process, illustrating NCM712-MWNT-PVDF composite preparation, hot pressing onto an etched Al foil, and subsequent roll pressing to form a dry press-coated electrode (DPCE).⁸

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Fig. 4. Schematic of the extrusion-based dry electrode fabrication process, illustrating powder and binder mixing, pelletizing, extrusion, debinding, and sintering for electrode formation.³⁵

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Roll-mill processing is the most widely implemented dry-electrode fabrication method, using shear mixing and rolling to produce uniform electrode films—even at high thicknesses. High-shear forces between rotating rollers thoroughly disperse dry powders, forming continuous electrode films with excellent uniformity.^14,26,28 Its compatibility with large-scale, roll-to-roll manufacturing makes roll-mill processing particularly attractive. For instance, Maxwell-Tesla uses a two-roll milling-based dry-coating process to create free-standing electrode films at scale, while Fraunhofer IWS has developed a multi-roll system that integrates compaction and lamination to reduce costs.^17,18,38

Fig. 5. Schematic of the roll mill processing for dry electrode fabrication, illustrating the mixing of active materials, conductive additives, and PTFE binder, followed by fibrillation, calendering, and lamination onto an Al current collector.¹⁵

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PTFE acts as the main binder in roll-mill processing. Under shear stress, PTFE forms fibrous networks that improve mechanical integrity and flexibility. However, the magnitude of shear forces depends on particle-size distribution; inadequate control risks film defects (e.g., cracks, edge deformation, or delamination).³⁹ Although PTFE-based formulations are popular, alternative binders with enhanced processability, and sustainability are actively under study. Despite these challenges, roll-mill processing remains a dominant technique for solvent-free electrode manufacturing, offering scalable and efficient pathways to next-generation battery electrodes.

Among the four dry electrode manufacturing techniques, roll mill processing is the most widely adopted method, primarily utilizing PTFE as a binder. PTFE is well-suited for dry processing due to its high thermal resistance, chemical stability, and electrochemical durability. Unlike conventional slurry-cast electrodes that often exhibit "moss-like" PVDF morphologies, solvent-free electrodes demonstrate a hierarchical PTFE fibril network, which spans tens of active material particles and facilitates improved ionic and electronic conductivity by ensuring open pores and uniform material distribution.⁴⁰

To effectively incorporate PTFE in dry electrodes, fibrillation is a crucial step. The unique polymer structure of PTFE consists of a carbon backbone bonded with four fluorine atoms per monomer unit, forming strong C-F bonds that allow PTFE to extend into a fibrous framework. This structural characteristic results in low van der Waals interactions and weak intermolecular stacking, making PTFE highly susceptible to fibrillation under shear forces. During processing, PTFE particles deform and interconnect, forming an entangled network that enhances mechanical integrity and material cohesion.^39-41

During shear mixing, rough surface particles interlock with PTFE crystallites, providing anchoring points for fibrillation. Initial fibrils, often a few microns in diameter, extend as particles slide past each other under shear forces. As the mixing process continues, secondary and tertiary fibrils emerge, forming a branch-like morphology that improves electrode uniformity. This hierarchical fibril structure effectively links active material particles and conductive additives, reinforcing both mechanical strength and electrical conductivity.^39-41

Figure 6 illustrates the PTFE fibrillation process through schematic representation and SEM imaging.⁴⁰ Initially, large PTFE particles deform and adhere to the active material surface. At this stage, primary fibrillation occurs, forming small fiber bundles. As shear force continues to be applied, secondary fibrillation takes place, where additional PTFE strands extend from the initial fibers, connecting surrounding active material particles. This multi-step fibrillation mechanism enhances electrode robustness and improves contact between active materials and conductive agents, ultimately contributing to superior electrochemical performance.^40,41

Fig. 6. Schematic representation and SEM images illustrating the PTFE fibrillation mechanism, where shear forces induce primary and secondary fibrillation, enhancing electrode uniformity and mechanical integrity.⁴⁰

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Temperature plays a significant role in optimizing PTFE fibrillation. As temperature increases, the kinetic energy of PTFE molecules rises, altering the polymer chain structure and reducing bond strength. This transition facilitates fibrillation by making PTFE more deformable.^42,43

Dynamic MechanicalAnalysis (DMA) data reveals a plateau region in the storage modulus between 60-110°C, indicating that PTFE maintains a stable fibrillar structure within this temperature range. In this phase, lamellar PTFE structures transition into fibrillar networks, improving mechanical stability and adhesion to active material particles. However, beyond 110°C, the storage modulus begins to decrease, correlating with PTFE’s glass transition temperature (Tg) of ~118°C. At temperatures exceeding Tg, PTFE exhibits fluid-like properties, leading to molecular rearrangement and film formation rather than fibrillation. Figure 7 presents the DMA analysis of PTFE, demonstrating how the fibrillation process is optimized within specific temperature ranges. This analysis underscores the importance of carefully controlling processing temperatures to ensure stable PTFE network formation while preventing excessive molecular mobility that may compromise electrode integrity.³⁹

Fig. 7. Dynamic Mechanical Analysis (DMA) of PTFE, showing the transition from a virgin state to a fibrillar structure and eventually a film-like state as temperature increases.³⁹

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One of the primary applications of dry electrode technology is its ability to produce thick electrodes, which are critical for achieving high energy densities. By eliminating the solvent-drying step inherent in wet processes, dry manufacturing minimizes issues such as binder migration and structural defects, including cracking and delamination. This ensures uniform material distribution and mechanical integrity, even in electrodes with high active material loadings. For example, roll mill processes enable the fabrication of thick cathodes exceeding 100 μm in thickness while maintaining consistent porosity and ionic pathways. This results in superior charge transport and electrochemical performance. These characteristics make dry-manufactured thick electrodes particularly valuable for EV and grid-scale energy storage systems, where achieving high energy density is essential.^8,15,39

Dry electrode technology’s compatibility with all-solid-state batteries (ASSBs) marks another significant advancement. ASSBs, which use solid electrolytes instead of liquid ones, require electrode fabrication methods that minimize porosity and ensure intimate contact between the electrolyte and active materials. Dry processes, such as hot pressing and roll mill techniques, effectively meet these demands by producing dense, uniform films that enhance solid-solid interfaces and reduce interfacial resistance. Furthermore, the absence of solvents eliminates chemical incompatibility issues commonly encountered in conventional wet processes.^37,44,45 These advantages position dry electrode manufacturing as a crucial enabler for the commercialization of ASSBs, which offer enhanced safety and energy density compared to traditional LIBs.

In addition to performance improvements, dry electrode technology significantly enhances the environmental sustainability of LIB manufacturing. By eliminating the use of toxic solvents such as NMP, dry processes reduce hazardous emissions and the energy consumption associated with solvent recovery and drying stages. This aligns with global sustainability goals and regulatory pressures to lower the carbon footprint of battery production. Moreover, the streamlined workflow of dry processes minimizes material waste and reduces operational costs, making dry electrode technology an economically and environmentally favorable solution for large-scale battery manufacturing.^27,46,47