Dry Process Technology: A Manufacturing Revolution and Performance Breakthrough for Lithium-Ion Batteries and Supercapacitors

Driven by the "dual carbon" goals (carbon peaking and carbon neutrality), lithium-ion batteries (LIBs) and supercapacitors—core energy storage devices in the new energy industry—are facing dual demands for "performance improvement" and "green manufacturing". For a long time, electrode preparation for both has relied on the traditional wet process. Taking lithium-ion batteries as an example, active materials must be mixed with toxic organic solvents such as N-methylpyrrolidone (NMP) to form a slurry, which is then coated on current collectors and dried at high temperatures to remove solvents. Supercapacitor electrode manufacturing follows a similar process. This method not only accounts for over 30% of the total energy consumption in battery production but also generates more than 500 tons of solvent waste per 1 GWh of lithium-ion batteries produced. Additionally, residual solvents easily lead to loose electrode structures, limiting the power density and cycle life of energy storage devices.

Today, breakthroughs in dry process technology are reshaping this landscape. Eliminating the need for solvents, high-temperature drying, and simplifying production workflows, dry process technology not only brings a "cost reduction and carbon emission reduction" manufacturing revolution to lithium-ion batteries and supercapacitors but also unlocks new potential in core performance metrics such as high power and long lifespan by reconstructing the microstructures of electrodes. It has become a key driver for the energy storage sector to shift from "scale expansion" to "high-quality development".

I. Dry Process Technology: The "Solvent-Free Manufacturing" Logic That Subverts Tradition

The core innovation of dry process technology lies in abandoning the wet process’s reliance on organic solvents and realizing electrode preparation through a technical route of "dry forming + in-situ composite". Its working principles can be divided into two categories:
One is "dry calendering": Active materials (e.g., lithium iron phosphate for LIBs, activated carbon for supercapacitors), conductive agents, and binders are mixed in proportions, formed into dry powder through high-speed shearing, and then directly pressed onto current collectors using precision calendering equipment to form a dense and uniform electrode layer.
The other is "electrospinning dry process": A high-voltage electric field is used to transform a mixed melt of polymers and active materials into nanoscale fibers, which are directly deposited on the surface of current collectors to form self-supporting electrodes with porous structures. These electrodes meet conductivity and mechanical strength requirements without additional calendering.

Compared with the traditional wet process, the advantages of dry process technology are nothing short of "dimension-reducing": From the manufacturing perspective, it eliminates links such as solvent procurement, slurry mixing, and high-temperature drying, reducing equipment investment by 20%, shortening the production cycle by 40%, cutting energy consumption by over 50%, and achieving "zero-pollution" production with no solvent waste discharge. From the material perspective, it avoids the collapse of micropores inside electrodes caused by solvent evaporation during drying, enabling precise control of electrode porosity (adjustable between 30%-60%) and providing smoother channels for ion transport.

II. Lithium-Ion Batteries: Dry Process Solves the Dilemma of "High Power vs. Low Cost"

For a long time, lithium-ion batteries have faced the challenge of balancing "energy density" and "power density". In wet-process electrodes, active material particles are easily wrapped by binders, creating tortuous ion transport paths that limit fast-charging performance and high-current discharge capabilities. Meanwhile, the high energy consumption and pollution of the wet process drive up the cost of power batteries, restricting their large-scale application in scenarios such as commercial vehicles and energy storage stations. The emergence of dry process technology has brought three major breakthroughs to lithium-ion batteries:

1. Leapfrog Fast-Charging Performance: 80% Charge in 10 Minutes Becomes Possible

Lithium iron phosphate battery electrodes prepared via dry calendering have more uniformly distributed active material particles and a "3D network" pore structure inside the electrode, increasing lithium-ion migration rates by more than 3 times. A domestic battery manufacturer using dry process technology to produce power batteries has achieved 80% charge in 10 minutes at room temperature, with a capacity retention rate of 90% after 1,500 cycles—far exceeding wet-process batteries (which typically have a capacity retention rate of about 80% after 1,000 cycles under the same conditions). This performance makes it particularly suitable for new energy commercial vehicles: charging time for heavy trucks, buses, and other models can be reduced from over 1 hour to less than 15 minutes, approaching the refueling efficiency of fuel vehicles.

2. Significant Cost Reduction: Driving Large-Scale Application of Energy Storage Batteries

The dry process eliminates solvent recovery systems and large-scale drying equipment, reducing the production cost of lithium-ion batteries by 15%-20% per GWh. Taking the 280Ah lithium iron phosphate battery commonly used in energy storage as an example, the dry process has reduced its unit cost from 0.6 CNY/Wh to below 0.5 CNY/Wh. Combined with the environmental advantages of solvent-free production, it has significant competitiveness in large-scale energy storage station tenders. Currently, domestic energy storage projects have adopted dry-process lithium-ion batteries, reducing the levelized cost of energy (LCOE) by 8% compared with traditional wet-process batteries and accelerating the transition of energy storage from "policy-driven" to "market-driven".

3. Enhanced Safety: Reduced Risk of Thermal Runaway

Residual solvents in wet-process electrodes easily decompose at high temperatures to produce gases, increasing the risk of battery swelling and thermal runaway. In contrast, dry-process electrodes have no solvent residues, and the active materials bond more tightly with current collectors during calendering, improving thermal stability. Test data shows that in nail penetration and extrusion tests, the maximum temperature of dry-process lithium-ion batteries is 40°C lower than that of wet-process batteries, with no fire or explosion—providing a safety guarantee for applications in energy storage stations, home energy storage, and other scenarios.

III. Supercapacitors: Dry Process Amplifies Core Advantages of "Power and Lifespan"

Supercapacitors, with their high power density and ultra-long cycle life, have been widely used in rail transit, industrial braking, and other scenarios. However, electrodes prepared by the traditional wet process have two major shortcomings: First, activated carbon particles tend to agglomerate, reducing the utilization rate of specific surface area and limiting energy density. Second, uneven binder distribution leads to easy electrode detachment after long-term high-frequency charging and discharging, affecting cycle life. The application of dry process technology has further amplified the advantages of supercapacitors:

1. Energy Density Breakthrough: Filling the Gap Between "Lithium-Ion Batteries and Traditional Capacitors"

Through the electrospinning dry process, the activated carbon electrodes of supercapacitors can form a "nanofiber-porous carbon" composite structure. The specific surface area increases from 1,500 m²/g (wet process) to over 2,500 m²/g, with a more concentrated pore size distribution (2-5 nm), significantly enhancing charge storage capacity. Currently, the energy density of supercapacitors prepared by the dry process has reached 15-20 Wh/kg—50% higher than traditional wet-process products and close to low-capacity lithium-ion batteries (about 25 Wh/kg)—while maintaining a power density of over 5,000 W/kg. This meets the "high power + medium energy" demands of new energy vehicle start-stop systems, rail transit braking, and other scenarios.

2. Cycle Life Upgrade: Plummeting Lifecycle Costs

In supercapacitor electrodes prepared by the dry process, binders combine with active materials through "molecular-level composite", avoiding binder aging caused by solvent evaporation in wet-process electrodes. Laboratory data shows that under high-frequency charging and discharging (1,000 cycles/day), dry-process supercapacitors have a cycle life of over 2 million times—far exceeding the 1 million times of wet-process products. Calculated based on 50 cycles/day in industrial scenarios, their service life can exceed 100 years, almost matching the lifespan of the equipment itself, and reducing lifecycle operation and maintenance costs by 70%.

3. Optimized Low-Temperature Performance: Enhanced Adaptability to Extreme Environments

In traditional wet-process supercapacitors, the increased viscosity of electrolyte in electrode pores at -30°C leads to a capacity decay rate of up to 30%. However, the porous electrode structure constructed by the dry process reduces the hindrance of low-temperature electrolyte solidification to ion transport. At -40°C, the capacity decay rate remains below 10%, with a charge-discharge efficiency of over 95%. This feature allows direct application in scenarios such as wind power energy storage in northern winter and plateau rail transit, without the need for additional heating systems.

IV. Challenges and Future: How Will Dry Process Technology Achieve Large-Scale Application?

Despite its significant advantages, dry process technology currently faces two major challenges: First, higher requirements for raw materials. The dry process requires more uniform particle size of active materials (with an error controlled within 5%) and binders with stronger interface adhesion, leading to a 5%-10% higher raw material cost than the wet process. Second, difficulty in controlling consistency in large-scale production. Especially during dry calendering, deviations in electrode thickness can affect device performance, requiring high-precision equipment and intelligent control systems.

Nevertheless, these issues are gradually being resolved with technological iteration and industrial supporting improvements: Domestic enterprises have developed low-cost binders dedicated to the dry process, narrowing the raw material cost gap to within 3%. Meanwhile, the introduction of AI visual inspection and real-time feedback systems has controlled the thickness deviation of dry-process electrodes to ±2 μm, meeting large-scale production requirements.

In the future, dry process technology will develop toward "multi-material compatibility" and "cross-device integration". On one hand, it can realize "co-line manufacturing" of lithium-ion batteries and supercapacitors, producing hybrid energy storage devices with both high energy and high power by adjusting the proportion of active materials. On the other hand, it is expected to integrate with new energy storage technologies such as solid-state batteries and sodium-ion batteries, further promoting the greenization and high-performance of the new energy industry.

The shift from wet to dry process is not only an upgrade in manufacturing technology but also a transformation of the energy storage industry from "high consumption" to "low carbon" and from "performance compromise" to "comprehensive breakthrough". With the popularization of dry process technology, lithium-ion batteries and supercapacitors will play greater roles in new energy vehicles, energy storage stations, smart grids, and other fields, injecting strong impetus into the achievement of "dual carbon" goals.