In
all-solid-state batteries, the liquid electrolyte is replaced by a solid-state
electrolyte membrane. Consequently, the front-end production process requires
the preparation of this solid electrolyte film in addition to the traditional
positive and negative electrode sheets. This process is a critical link in the
battery manufacturing workflow, directly determining the performance and
quality of the final cell. While the wet process currently dominates
solid-state battery production lines, the dry process is increasingly becoming
the mainstream direction for next-generation solid-state battery front-end
technology, thanks to its combined advantages in cost, process efficiency, and
material compatibility.
01.
Key Upgrades in Solid-State Battery Pre-Forming Production
The
manufacturing process for solid-state batteries fundamentally differs from that
of traditional liquid batteries. The front-end film preparation segment is the
critical, transitional phase in the battery manufacturing process. This stage
directly dictates the finished cell's energy density, rate performance, and
cycle life. In all-solid-state batteries, the solid-state electrolyte membrane
replaces the liquid electrolyte. Therefore, front-end preparation must include
not only the conventional positive and negative electrode sheets but also the
solid-state electrolyte film. This fundamental change introduces new challenges
and simultaneously presents opportunities for process upgrading.
02.
Technological Transformation: The Leap from Wet to Dry Process
Current
solid-state battery front-end preparation processes are mainly categorized into
two technical routes: wet and dry. The wet process still relies on the solvent
system of traditional liquid batteries, where electrode or electrolyte
materials are mixed with a binder to form a slurry, coated, and then dried to
complete film formation.
While
this process is relatively mature, it has inherent drawbacks: it requires the
use of large amounts of toxic organic solvents (such as NMP), necessitates
high-energy-consumption steps for drying and solvent recovery, and restricts
the application of certain cutting-edge materials sensitive to solvents.
In
contrast, the dry process innovates electrode manufacturing by eliminating the
use of solvents and the subsequent drying step. The dry process relies more
heavily on high-shear dry mixing and fibrillation equipment to achieve uniform
material dispersion and pre-forming, followed by multi-roll pressing to
complete the film formation directly.
The core
advantages of dry film formation technology are evident across three
dimensions:
• Cost
Efficiency: By omitting the coating, drying, and solvent recovery stages,
equipment investment is lower, energy consumption is reduced, and overall cell
manufacturing costs can be reduced by approximately 18%.
• Performance
Enhancement: The dry process effectively increases the active material's
compaction density, leading to an energy density increase of about 20%. SAIC
Group's semi-solid-state battery, integrated into its MG4 model, has achieved a
system energy density of 400Wh/kg, supporting a 12-minute fast charge for 400
km.
• Environmental
and Material Compatibility: The dry process eliminates the need for toxic
solvents, solving the environmental pollution issues of the traditional wet
process. Concurrently, it enables the application of more cost-effective
materials (such as manganese-based cathodes).
03.
Technology Matrix: Diversified Paths for Dry Film Formation
Dry film
formation is not a single process but a matrix encompassing various technical
routes. Currently, the more representative dry electrode preparation
technologies primarily include six types:
• Fibrillation
Method: Uses high shear force to fibrillate the binder, enabling it to tightly
encapsulate active materials and conductive agents, forming a self-supporting
electrode film. This process demands extremely high shear force and temperature
control capabilities from the equipment.
• Dry
Spray Deposition: Utilizes charged powder, which is uniformly deposited onto
the current collector under an electric field, followed by hot pressing to melt
and fix the binder, forming a self-supporting film.
• Other
Methods: Vapor deposition, hot-melt extrusion, direct pressing, and 3D printing
are applied based on different material characteristics and application
scenarios.
These
different paths vary in technical principles, applicable materials,
film-forming capability, and equipment complexity, and are suited for different
applications such as large-scale, flexible electrodes, small-sized devices, and
thick electrode sheets.
Comparison
of Major Dry Film Formation Technical Routes
|
Technical
Route
|
Core
Principle
|
Applicable
Scenarios
|
Equipment
Complexity
|
|
Fibrillation
Method
|
High
shear force fibrillates binder to wrap active material
|
Large
electrodes, all-solid-state batteries
|
High
|
|
Dry
Spray Deposition
|
Electrostatic
powder deposition followed by hot pressing
|
Flexible
electrodes, complex shapes
|
Medium
|
|
Direct
Pressing
|
Direct
pressing and forming of powder material
|
Thick
electrode sheets, experimental lines
|
Low
|
|
3D
Printing
|
Layer-by-layer
accumulation and forming
|
Small-sized
devices, customized structures
|
High
|
The
industry generally considers the Binder Fibrillation Method to exhibit superior
performance stability and processability, positioning it as the emerging
mainstream route.
04.
Industrialization Challenges: Bridging the Gap from Laboratory to Mass
Production
Despite
the clear advantages of dry film formation, scaling from the laboratory to mass
production faces numerous hurdles. Capacity and efficiency are paramount
concerns. Dry coating capacity and speed still lag behind traditional wet
processes, and uniformity and adhesion performance during wide-format spraying
require significant improvement.
Coating
uniformity and quality control present another major challenge. Non-uniform dry
electrode coatings can create "hot spots" within the electrode,
leading to accelerated battery performance degradation and potential safety
risks.
Binder
and material compatibility also need further optimization. Achieving uniform
distribution of PTFE fibrils within the mixture while preventing damage to active
material particles is essential. Furthermore, PTFE is unstable at low
potentials and reacts irreversibly with lithium, which limits its application
in negative electrodes.
Challenges
on the equipment side are equally severe. The dry process imposes higher
demands on core roller-pressing machinery. The performance and production
efficiency of the calendaring machine as the core equipment are central to
determining the dry process's viability for mass production.
TOB
NEW ENERGY is actively working to address these
challenges, aiming to control the binder content in the negative electrode to
0.7% and the positive electrode below 1.5% to achieve more efficient, low-cost
film-forming performance.
05.
Equipment Innovation: The Critical Force Driving Dry Process Implementation
Equipment
typically spearheads the industrialization of solid-state batteries. In the
realm of dry film formation, equipment innovation is the key driver for
technological implementation.
• Front-End
Process Equipment: Accounts for approximately 32% of the entire production
line's value, including core equipment for high-efficiency mixing, material
dispersion, coating, and high-shear treatment.
• Mid-End
Process Equipment: Accounts for approximately 45% of the line's value, centered
around high-efficiency stacking machine (25% of the line's value) and horizontal
isostatic presses (13% of the line's value), covering the entire process from
shaping to densification.
• Back-End
Process Equipment: Accounts for approximately 23% of the line's value,
including dry powder comprehensive testers and horizontal high-temperature
fixture solutions for solid-state battery integrated cabinets, achieving
high-voltage formation and capacity grading and assembly.
06.
TOB NEW ENERGY: Providing Comprehensive Solutions from Laboratory to Mass
Production
Addressing
the industrialization opportunities and challenges of dry film formation
technology, TOB NEW ENERGY leverages years of technical accumulation in battery
manufacturing to offer customers a complete solution spanning from the
laboratory to mass production.
Solutions
for Laboratory-Scale Dry Electrode Lines
We
provide a full suite of customized equipment and services for dry electrode
experimental lines. Our developed Laboratory Jet Mill integrates
miniaturization, intelligence, and high precision, suitable for
experimental-grade powder preparation needed for the fibrillation of lithium
battery dry electrode materials. The Lab Dry Electrode Film Forming Machine is a laboratory dry electrode research equipment that can be used for the powder to film forming process.
Solutions
for Pilot-Scale Production
We offer Dry Electrode Film Forming Machines that support various production line
requirements, including equipment for GWh-level mass production capacity.
Through precise tension control and thickness adjustment, we can achieve the
preparation of dry electrode sheets as thin as 27μm or
even thinner.
Solutions
for Industrial Mass Production
For
industrial mass production needs, we provide complete dry electrode
production line solutions. Our system covers all processes, including
controllable feeding, film formation, thinning, current collector compounding,
and quality inspection. Product width can reach 1000mm, with a thickness range
of 40-300μm, and is compatible with 2 to 6 dry
electrode sheets operating in parallel for high-efficiency production.
Our
technical team deeply understands every aspect of the dry film formation
process and can provide customized process optimization solutions based on the
client’s specific material systems (such as
graphite/silicon-carbon negative electrodes, ternary/LFP positive electrodes,
and various all-solid-state electrode materials) and equipment needs. On the
materials front, we support our clients with cutting-edge battery materials,
including specialized binders and modified conductive agents suitable for the
dry process, ensuring optimal compatibility between materials and process.
