21700 Battery Dry Electrode Process: Technological Innovation and Industrialization Progress

Blog | Published by Alex on June 22, 2026

Introduction

Driven by the pursuit of higher energy density, lower cost, and improved safety in the lithium-ion battery industry, electrode manufacturing is undergoing a profound transformation from traditional wet coating to dry electrode technology. The 21700 cylindrical cell, as a key platform for power batteries, power tools, and emerging applications such as eVTOL aircraft, has become a primary focus for this technological evolution. By completely eliminating solvent usage and relying on binder fibrillation technology, the dry electrode process is reshaping the manufacturing paradigm for 21700 battery cells.

Process Principles and Core Differences

Conventional wet processes require dispersing active materials, conductive agents, and binders in organic solvents such as NMP to form a slurry, which then undergoes coating, drying, and solvent recovery. The dry process eliminates solvents entirely. Its technical cornerstone lies in the fibrillation characteristics of dry-process binders (primarily PTFE) under mechanical shearing. After mixing and fibrillation, the powder materials directly form a self-supporting electrode film, which is then thermally laminated with current collectors to produce electrodes.

This fundamental difference results in a radical restructuring of the process chain. The dry process eliminates slurry mixing, coating, electrode drying, and solvent recovery, replacing them with a dry-film formation step. From a materials perspective, the binder system shifts from PVDF for cathodes and CMC+SBR for anodes in wet processes, to fibrillation-capable PTFE. From an equipment standpoint, coaters and drying ovens are replaced by fibrillation equipment (such as jet mills and screw extruders) and high-performance calenders.

Core Advantages: Multi-Dimensional Gains in Performance, Cost, and Safety

The advantages of the dry process for 21700 battery cells are multi-faceted. In terms of electrochemical performance, because the drying process no longer causes excessive binder coverage over active material surfaces, dry electrodes form a point-contact conductive network, leaving active surfaces more exposed and facilitating rapid lithium-ion transport. Studies show that dry electrodes can achieve 8% to 32% higher compaction density (depending on material systems) and up to 20% higher energy density compared to wet electrodes. In rate capability, dry electrodes exhibit lower charge-transfer resistance and ionic diffusion resistance, delivering significantly superior capacity retention at high discharge rates.

In manufacturing cost and environmental impact, the benefits are more direct. Eliminating NMP solvent saves raw material costs while removing the environmental and safety risks associated with toxic solvents. Data from the EU's C2C project (Customized 21700 Cylindrical Cells) indicates that the dry process can reduce cell-level energy consumption by approximately 27% and cut the carbon footprint per cell by about 5%. Moreover, the streamlined process reduces floor space, capital equipment investment, and environmental control operating costs. Industry analysis suggests that the dry process can lower manufacturing costs by approximately 18%.

Regarding safety, the dry process offers unique value. Since no solvents are required, dry electrode films can be made thicker without cracking and exhibit better flexibility. More notably, patented technologies from Chinese battery manufacturers demonstrate that by integrating the separator with the dry electrode film and current collector through a one-step thermal roll lamination, a self-supported electrode with an integrated separator can be produced. Under extreme conditions such as nail penetration, the electrode and separator do not misalign, and the dry electrode effectively restricts separator shrinkage at high temperatures, thereby preventing direct short circuits between anode and cathode.

Key Performance Data and Comparisons

The following table summarizes the claimed core advantages and relevant data for the dry electrode process:

For reference, the following table presents test parameters for a conventional 21700 cell from a recent paper published in Nature, providing a baseline for understanding where dry-process improvements may have the greatest impact:

Industrialization Progress: From Lab to Production Lines

The dry electrode process for 21700 battery cells is accelerating its transition from laboratory to mass production. In Europe, the EU-funded C2C project has successfully produced high-quality dry-process cathodes and anodes at pilot scale and integrated them into 21700 A-sample prototype cells featuring lightweight casings, achieving gravimetric energy density significantly exceeding comparable commercial products, with plans to further develop B-sample cells.

On the industry collaboration front, Germany's IKA Group and UniverCell have signed a joint development agreement to combine IKA's continuous kneading technology (CONTERNA) with UniverCell's 21700 cell design, advancing dry electrode technology from pilot to scalable production. UniverCell's 21700 platform combines tabless design, optimized thermal management, and lightweight construction, targeting a capacity of 6.0 Ah for high-end applications including aerospace and electric mobility.

In China, companies such as SVOLT have filed multiple patents on integrated dry electrode fabrication processes, emphasizing the direct thermal roll lamination of separators, dry electrode films, and current collectors into unified electrodes to improve stacking efficiency and cell safety.

Challenges and Outlook

Despite its promising prospects, the dry electrode process still faces critical challenges. First, high-performance modified PTFE binders suitable for dry processing are not yet fully mature, and standard PTFE cannot easily meet the requirements. Second, the process imposes extremely high demands on calendering equipment—conventional wet-process calenders operate at pressures below 100 tons, whereas dry film formation requires pressures reaching thousands of tons. Uniform fibrillation of binders and mechanical consistency of self-supporting films also remain difficult hurdles for industrial-scale production.

Additionally, it should be noted that the dry electrode process has not yet achieved large-scale commercial application for 21700 battery cells. The data cited above primarily reflects the technology's potential, and whether these advantages can be fully realized in mass production—along with the balance between cost, performance, and lifespan—will require validation through actual production data.

Summarize

The dry electrode process for 21700 cells represents a paradigm shift from "wet" to "dry" manufacturing. Beginning with the elimination of solvents, it drives systematic improvements in cost, performance, environmental sustainability, and safety. With continued advances from pioneers such as the EU C2C project and UniverCell, along with the maturing of supporting supply chains for binders and equipment, dry electrode technology is poised to become the standard process for 21700 and next-generation cylindrical cells, delivering higher-performance and more sustainable battery solutions for electric aviation, premium automotive, and other emerging applications.

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Note: All data and claims presented are based on publicly available information from industry announcements, technical papers, and company disclosures as of the time of writing. Actual performance may vary with specific cell designs and manufacturing conditions.