Process Adaptation Comparison for Solid-State Batteries: Can Dry Electrodes Replace Traditional Wet Electrodes?

Solid-state batteries completely eliminate liquid electrolytes and rely on solid electrolytes for ion transmission. With disruptive advantages in energy density, safety performance and cycle life, they have become the core development direction of next-generation energy storage and power batteries. As a key procedure in battery manufacturing, the traditional wet coating process inherits the mature system of liquid batteries but has inherent limitations when applied to solid-state batteries. Featuring solvent-free operation, stable structural performance, excellent interfacial contact, and low energy consumption and cost, the solvent-free dry electrode process is highly compatible with the material system and mass production requirements of solid-state batteries. Focusing on the core industry question — whether dry electrodes can fully replace traditional wet electrodes for solid-state battery mass production — this article conducts an objective comparative analysis from four dimensions: process adaptability, performance manifestation, mass production bottlenecks and application scenarios.

1. Fundamental Adaptation Differences Between the Two Processes

The traditional wet electrode process adopts an organic solvent system to mix active materials, conductive agents and binders into liquid slurry, which is then processed through coating, high-temperature drying and solvent recovery to complete electrode preparation. This process is well-suited for traditional liquid batteries, where liquid electrolyte infiltration can compensate for microscopic electrode defects and optimize ion transmission. However, solid-state batteries have no liquid electrolyte for penetration and filling, which fully exposes the inherent shortcomings of the wet process and greatly limits its adaptability.

The solvent-free dry electrode process adopts an entirely physical forming method. Electrodes are fabricated through powder dry mixing, PTFE fibrillation bridging and constant-temperature hot-press film forming. The whole process requires no solvents, high-temperature drying or material migration. The finished electrodes feature uniform pore structure, dense material bonding and stable interfacial contact, which perfectly matches the core operating mechanism of solid-state batteries — solid-solid contact without liquid infiltration — and fundamentally adapts to the technical characteristics of solid-state battery systems.

2. Core Limitations of Wet Electrodes in Solid-State Battery Applications

2.1 Poor solid-solid interfacial contact and rapid performance degradation: The high-temperature drying procedure of the wet process easily causes active material agglomeration, particle migration and uneven internal pores, resulting in loose microscopic electrode structures. Liquid batteries can compensate for voids through electrolyte infiltration, while solid-state batteries have limited solid-solid contact areas. Loose electrode structures hinder ion transmission, increase interfacial impedance, and lead to contact failure and rapid capacity attenuation after long-term cycling. Test data shows that wet electrodes achieve only 33.3% effective contact coverage in solid-state systems, significantly restricting battery performance release.

2.2 Solvent residues threaten cell stability: The wet process cannot completely avoid trace solvent residues. These residual substances cause side reactions with solid electrolytes, damage interfacial stability, and reduce the cycle life and safety performance of batteries, becoming a hidden hazard for the long-term stable operation of solid-state batteries.

2.3 High energy consumption and high production costs: The wet process relies on energy-intensive procedures including slurry preparation, long-distance drying, and NMP solvent recovery and rectification. Drying and solvent recovery alone account for approximately 46% of total production energy consumption. In addition, high costs from solvent consumption, equipment investment, environmental operation and maintenance, and plant occupation make it difficult to meet the large-scale cost reduction requirements of solid-state battery mass production.

2.4 Insufficient process compatibility: Most solid electrolyte materials are sensitive powders that cannot withstand high temperatures and are vulnerable to interference from liquid systems. The liquid-phase stirring and high-temperature drying procedures of the wet process may damage the activity of solid materials and weaken the overall electrochemical performance of cells.

3. Core Advantages of Dry Electrodes for Solid-State Battery Adaptation

3.1 Optimized solid-solid interface and improved electrochemical performance: The dry process uniformly wraps active materials through a physical fibrillar network structure, producing electrodes with dense internal structures and controllable pores without drying stress or material migration. When applied to solid-state batteries, dry electrodes achieve sufficient contact with solid electrolytes, with effective contact coverage reaching 67.2%. This significantly reduces interfacial impedance, improves ion conduction efficiency, fully releases battery energy density and rate performance, and delivers substantially better cycling stability than wet electrodes.

3.2 Zero solvent residues and wide material compatibility: The entire process involves no organic solvents, completely eliminating side reactions caused by solvent residues. It is perfectly compatible with various solid electrolyte systems including sulfides, oxides and polymers, maximally retaining the intrinsic performance of active materials and electrolytes, and ensuring long-term stable operation of battery cells.

3.3 Energy saving and cost reduction for large-scale mass production: By eliminating all high-energy-consuming wet procedures, the dry process reduces comprehensive production line energy consumption by 38%–46%, cuts fixed asset investment by 10%–15%, and reduces production line floor area by approximately 70%. It also lowers material loss, environmental operation and maintenance costs, achieving an overall manufacturing cost reduction of 10%–20% and solving the core cost bottleneck restricting large-scale solid-state battery production.

3.4 Superior structural stability and longer cycle life: Dry electrodes maintain stable interlayer bonding force with minimal structural deformation during charge and discharge cycles, effectively inhibiting internal resistance growth and slowing capacity attenuation. Under the same material system and production specifications, solid-state batteries equipped with dry electrodes achieve a 10%–20% longer cycle life, along with better high-temperature stability and batch consistency than wet electrode cells.

4. Objective Status: Substitution Boundaries and Mass Production Progress

In terms of technical adaptability, dry electrodes are the optimal process for solid-state batteries and fully meet the technical conditions to replace wet electrodes, representing a widely recognized mainstream technical direction for the industry. However, limited by the large-scale iteration of supporting equipment and the improvement of process standardization systems, full universal substitution has not yet been realized in actual mass production, with phased application boundaries existing at this stage.

Current solid-state battery mass production adopts a "dry-wet combined" transition solution. The mature and stable wet process is mainly applied to electrolyte layers and auxiliary negative electrode preparation, while the dry process is preferentially deployed for core positive electrodes and high-performance solid-state cells. The core restriction lies in the ongoing iteration and optimization of large-scale dry-process production equipment and standardized processes, rather than insufficient technical adaptability. The industry is currently in a stage of wet process upgrading and incremental dry process substitution.

As solid-state batteries evolve toward higher energy density, longer cycle life and lower-cost large-scale manufacturing, the inherent shortcomings of the wet process will become increasingly prominent. The dry process’s core advantages in interface adaptation, performance stability and production cost will continue to expand, achieving gradual dominant substitution of traditional wet processes in the future.

5. Conclusion

The core logic of process matching for solid-state batteries focuses on adapting to solid-solid interface characteristics, rather than simply inheriting mature wet processes. Restricted by the inherent attributes of liquid-phase manufacturing, traditional wet electrodes suffer from poor interfacial contact, rapid performance attenuation, high energy consumption and costs, and weak material compatibility, limiting their role as only a transitional process for current mass production. Fundamentally matching the structural and material characteristics of solid-state batteries, the solvent-free dry electrode process delivers all-round advantages in interfacial stability, electrochemical performance, energy conservation and long-cycle stability. Technically, it can completely replace wet electrodes; in mass production, substitution and industrialization are being rapidly promoted, serving as a core process support for the large-scale, industrialized and high-end development of solid-state batteries.