Latest Developments in Solid State Battery Processes 2025
Solid State Battery Core Process Difference Matrix
| process steps | Liquid lithium battery | Semi-solid state battery | All-solid-state battery |
|---|---|---|---|
| Front section – electrode sheet manufacturing | Wet coating (NMP solvent) | Wet coating + membrane modification | Dry electrode/wet film formation |
| Electrolyte treatment | Electrolyte injection | Slightly saturated (electrolyte reduced by 30%) | Solid Electrolyte Membrane Integration |
| Middle section – Cell forming | Winding/stacking + liquid injection | Compatible with traditional laminated coils | Isostatic pressing + adhesive frame lamination |
| Back end – Activation | Chemical decomposition | Pre-lithiation + capacity separation | High-pressure conversion (＞10MPa)） |
| critical equipment | Coating machine/liquid filling machine | High Porosity Membrane Production Line | Dry roller press/isostatic press equipment |
I. Semi-solid-state batteries: progressive process upgrades
1. Diaphragm technology innovation
Pore size increased to 200-400nm (50-100nm for traditional diaphragm)
Wet stretching + ceramic coating to improve strength (puncture force>500gf)
2. Pre-lithiation core process
Lithium replenishment: 5-8% (to compensate for first time efficiency loss)
Comparison of solutions:
| technical approach | Applicable scenarios | Energy density gain |
|---|---|---|
| Silicon anode pre-lithiation | High nickel ternary system | +15% |
| Lithium supplement for positive electrodes | lithium iron phosphate | +8% |
Case study: Weilan New Energy’s semi-solid-state battery achieves 360Wh/kg through lithium supplementation in the cathode
II. All-solid-state batteries: dry/wet route showdown
▶ Dry Electrode Process
Process:
Dry blending of actives + PTFE –> Fibrillization –> Thermal calendering –> Compounding with fluid collectors
Advantage:
- Solvent-free use (eliminates NMP recycling)
- Electrode density ＞3.5g/cm³ (wet ≤3.2g/cm³)
Challenges:
- Thickness uniformity ±3μm → Nano-scale powder dispersion required
- Equipment requirements: twin-screw extruder accuracy ±0.5°C
▶ Wet Film Formation Process
Innovative direction:
- Sulfide electrolyte: use of cyclohexane non-polar solvent (to avoid side reactions)
- Ultra-thin coating: electrolyte film thickness 10-20 μm (dry >30 μm)
Limitations:
- Poor compatibility of lithium metal anode (solvent residue leads to dendrites)
III. Subversive changes in the process of the middle and back section
1. Isostatic pressure technology
Pressure range: 200-300MPa
Effect: Solid-solid interface contact resistance <50Ω-cm²
2. High Pressure Formation
Activation mechanism: Lithium ion channel molding under 10MPa pressure
vs. traditional formation:
| parameters | liquid battery | All-solid-state battery |
|---|---|---|
| energy loss | 8-10% | 15-20% |
| Improved cycle life | 1.2 times | 3 times |
IV.The equipment side of the transformation and upgrading path
1. Dry core equipment
High-mixing machine:
Inert atmosphere control (oxygen content <10ppm)
Dispersion uniformity CV value <5%
Fiberization equipment:
KJI screw extruder temperature control ±1℃
Roller press:
Pressure accuracy ±0.1kN (traditional ±1kN)
2. Wet compatibility program
Coating machine modification:
Micro-gravure coating head (accuracy ±1μm)
Flash drying instead of hot air (solvent residue <10ppm)
Industrialization bottleneck and breakthrough direction
1. Dry process consistency problem
Solution:
Nano-coated active substance (primary particle D50=200nm)
AI vision real-time monitoring of membrane defects (detection rate 99.99%)
2. Electrolyte membrane thickness paradox
Optimize the equilibrium:
| thickness | advantage | risk |
|---|---|---|
| ＜20μm | energy density＞400Wh/kg | Poor mechanical strength (increased breakage rate) |
| ＞30μm | Thermal runaway temperature > 300°C | Internal resistance increased by 20% |
3. Pre-lithiation technology route
- Lithium metal foil: compatible with dry process (Phaidon Technology solution)
- Lithium silicide powder: wet slurry mixing addition (Tsing Tao Energy patent)
