Application of Dry Electrode in Supercapacitors and Lithium - ion Batteries

In the rapidly evolving landscape of energy storage technologies, innovations in electrode manufacturing processes directly define the performance limits of energy storage devices. Dry electrode technology, as a solvent-free green manufacturing approach, has demonstrated irreplaceable application value in both supercapacitors and lithium-ion batteries—two dominant energy storage systems. It not only overcomes the material limitations of traditional wet processes but also provides a novel pathway for performance enhancement in these devices through flexible structural design, serving as a critical bridge between different energy storage technologies.

1. Core Technology of Dry Electrodes: From Process Characteristics to Application Adaptability

The fundamental advantage of dry electrodes lies in their "solvent-free, physically formed" nature. Unlike wet processes that rely on organic solvents to dissolve binders and form slurries, dry processes utilize mechanical forces (such as shearing, stretching, and rolling) to directly blend active materials, conductive agents, and solid binders into a three-dimensional network structure. This structure endows dry electrodes with three key features: highly tunable porosity (30%-60% adjustable), facilitating efficient ion migration; elastic binder networks that buffer volume changes during charge-discharge cycles; and pure interfaces free from solvent residues that could interfere with electrode-electrolyte reactions.

These characteristics enable dry electrodes to meet the distinct requirements of supercapacitors and lithium-ion batteries. Supercapacitors, which rely on rapid ion adsorption/desorption for high-power output, demand electrodes with high conductivity and porous structures. Lithium-ion batteries, focused on high energy density and long cycle life, require uniform material distribution and structural stability. By adjusting parameters such as fiberization degree and rolling density, dry electrodes can be tailored to satisfy the core needs of both device types, demonstrating strong application adaptability.

2. Advanced Applications of Dry Electrodes in Supercapacitors

Supercapacitors, as high-power energy storage devices, face the critical challenge of balancing energy density and power density. Dry electrode technology addresses this bottleneck through structural innovations, achieving significant performance gains in various applications.

In terms of material compatibility, dry processes efficiently handle common supercapacitor materials such as activated carbon, carbon nanotubes, and graphene. Traditional wet processes often suffer from uneven solvent infiltration, reducing carbon material conductivity. In contrast, dry mechanical mixing ensures uniform distribution of conductive agents on carbon surfaces, increasing electrode conductivity by 20%-30%. Experimental data shows that supercapacitors using dry electrodes achieve a power density of 15 kW/kg—40% higher than wet-processed counterparts—making them ideal for high-frequency charge-discharge scenarios like regenerative braking and grid frequency regulation.

The three-dimensional porous structure of dry electrodes is pivotal for enhancing supercapacitor energy density. By controlling the distribution density of fiberized binders, continuous "ion highways" form within the electrode, increasing electrolyte wettability to over 98% and boosting effective capacity by 15%. In rail transit, trams equipped with dry-electrode supercapacitors achieve 30 km range on a single charge with 30-second recharging, improving operational efficiency by 50% compared to wet-electrode systems.

Dry electrodes excel in low-temperature performance, with no solvent residues reducing electrode-electrolyte interface impedance by 50%. At -40°C, capacity retention remains at 85%—significantly higher than the 60% of wet electrodes—making them indispensable for cold-climate applications like wind turbine pitch control and military backup power.

3. Innovative Applications of Dry Electrodes in Lithium-ion Batteries

Lithium-ion batteries' pursuit of extreme energy density and cycle life has highlighted the unique value of dry electrodes. From liquid electrolyte to solid-state batteries, dry processes drive performance breakthroughs through material adaptation and structural innovation.

In liquid electrolyte lithium-ion batteries, dry electrodes solve critical issues with high-capacity materials. Silicon-based anodes (theoretical capacity 4200 mAh/g), which expand 300%-400% during cycling, often crack in wet-processed electrodes. Dry electrodes' elastic binder networks buffer expansion stress, extending silicon-based battery cycle life to over 2000 cycles—three times that of wet-processed versions. For cathodes, dry processes prevent oxidation of high-nickel NCM811 materials during wet drying, enabling 350 Wh/kg energy densities to support EV ranges exceeding 1000 km.

Dry electrodes are transformative for solid-state lithium-ion batteries. Their porous structure addresses the low ionic conductivity of solid electrolytes by increasing interface contact area, reducing impedance by 60%. Qingyan Electronics' dry composite electrodes integrate active materials with solid electrolyte powders into a unified structure, achieving 450 Wh/kg energy density and 85% capacity retention at -40°C—removing key barriers to solid-state battery commercialization.

In cost reduction, dry electrodes eliminate solvent procurement and recovery costs, cutting energy use by 60% and overall production costs by 20%-25%. For energy storage systems, dry-electrode lithium iron phosphate batteries achieve 0.28 yuan/kWh—0.07 yuan lower than wet-processed alternatives—accelerating grid-scale storage adoption.

4. Cross-Field Synergies and Divergent Technical Paths

Dry electrodes' applications in both supercapacitors and lithium-ion batteries reveal shared advantages and distinct optimization strategies. Common benefits include environmental sustainability (99% reduction in VOC emissions), cost efficiency (20%-25% lower production costs), and material versatility (compatibility with carbons, oxides, and composites).

Divergent approaches stem from differing energy storage mechanisms: Supercapacitor dry electrodes prioritize conductivity and porosity (1.0-1.2 g/cm³ density) through high fiberization; lithium-ion dry electrodes balance energy density and stability with gradient rolling (3.0-3.5 g/cm³ for cathodes, 1.5-1.8 g/cm³ for anodes).

This divergence drives specialized innovations: "Carbon nanotube-activated carbon" dry electrodes enhance supercapacitor performance, while "silicon-carbon" core-shell structures improve lithium-ion battery durability. Qingyan Electronics' modular equipment enables flexible production switching between electrode types in under 2 hours, maximizing manufacturing efficiency.

5. Future Directions: Integration and Expansion

As energy storage technologies converge (e.g., lithium-ion capacitors), dry electrodes will increasingly bridge supercapacitors and batteries. Next-generation dry processes will advance through "material-equipment-application" integration: novel binders balancing conductivity and elasticity; intelligent systems for precise porosity/density control; and customized solutions for automotive, grid, and military applications.

Dry electrodes' widespread adoption is reshaping the energy storage industry, enabling Chinese enterprises to lead through original innovations rather than wet-process dependence. As dry electrode penetration grows, both supercapacitors and lithium-ion batteries will achieve performance leaps, powering cleaner transportation, smarter grids, and renewable energy integration—accelerating the global energy transition.