What is 21700 Battery OEM ODM Manufacturing?
Blog | Published by Alex on August 1, 2025
1. 21700 Battery Background and Market Demand
The
21700 Battery cylindrical cell has become a key battery format across electric vehicles (EVs), energy storage systems (ESS), and power tools due to its high energy density, cost efficiency, and manufacturing maturity. According to EVTank, global shipments of 21700 Battery cells exceeded 60 GWh in 2024, with a year-on-year growth of over 20%. As brands demand higher capacity, shorter lead times, and tighter quality consistency, professional OEM/ODM battery manufacturing is now a critical link in the supply chain.
2. 21700 Battery Technical Specifications and Performance Parameters
| Parameter |
Typical Range |
| Dimensions |
Diameter: 21 mm × Height: 70 mm |
| Cell Capacity (NCM811) |
3300–6000 mAh |
| Nominal Voltage |
3.6V / 3.7V |
| Energy Density |
230–270 Wh/kg |
| Cycle Life (80% DOD) |
≥1000 cycles |
| Continuous Discharge Rate |
1C–2C; Pulse: up to 3C–5C |
| Internal Resistance (AC 1kHz) |
≤22 mΩ (Typical 15–25 mΩ) |
3. Core Manufacturing Processes of 21700 Battery OEM
1) Electrode Preparation
Slurry Mixing: Automated vacuum planetary mixers with PLC control ensure homogeneous slurry without air bubbles.
Coating: Dual-side simultaneous coating lines, operating at ≥80 m/min with thickness control of ±1.5μm.
Calendering: Multi-roller high-precision calender machines maintain electrode compaction density at 3.4–3.6 g/cm³ (cathode).
2) Slitting and Winding
Slitting Accuracy: Precision cutting with deviation ≤ ±0.05 mm; anti-burr, anti-powder shedding.
Winding: High-speed multi-station winders with CCD alignment; offset control < ±0.2 mm.
3) Assembly and Electrolyte Filling
Case Assembly: Laser or ultrasonic welding ensures structural integrity and consistency.
Vacuum Filling: Electrolyte dosing accuracy within ±0.03g; typical electrolyte system: EC + DMC + EMC + LiPF6.
4) Formation and Grading
Formation: Multi-channel formation under controlled temperature and voltage for stable SEI film formation.
Grading: Testing of initial capacity, internal resistance, and voltage consistency:
Capacity deviation: < 20 mAh
Voltage deviation: < 10 mV
Internal resistance deviation: < 2 mΩ
4. 21700 Battery Key Equipment Configuration
| Process |
Equipment |
Performance Parameters |
| Mixing |
Dual-shaft vacuum planetary mixer |
Viscosity: 3000–8000 cp |
| Coating |
High-speed dual-side coater |
Thickness ±1.5μm, auto tension control |
| Calendering |
Six-roller precision calender |
Density control ±0.02 g/cm³ |
| Slitting |
Burr-free high-speed slitter |
Smooth edges, anti-burr |
| Winding |
CCD servo-position winders |
Deviation ±0.2 mm, auto separator control |
| Welding |
Laser tab welding system |
Depth control ±0.01 mm, <1% spatter |
| Electrolyte |
Vacuum precision filler |
Accuracy ±0.03g, with thermal control |
| Formation |
Multi-channel BTS tester |
Accuracy 0.05%, up to 256 channels |
5. Quality Control System
A full
MES +
SPC traceability system is in place, enabling complete tracking from coating to warehousing for every single cell.
Key Quality Control Points:
IQC: Incoming inspection of cathode/anode materials, moisture content, and conductivity.
IPQC: Monitoring winding yield, welding strength sampling.
FQC: Final capacity sorting, pressure drop, internal resistance classification (Grade A/B).
Routine Reliability Testing: Thermal shock, high-temperature aging, nail penetration, crush, safety standards.
6. 21700 Battery OEM/ODM Capabilities
Contract manufacturing based on client materials and specifications.
In-house design of cell structure, chemistry, and battery pack integration.
Customizable Parameters:
Capacity: 3300~6000 mAh
Chemistry: NCM811 / NCM622 / LFP
Max Continuous Discharge Rate: 3C~10C
Max Continuous Fast Rate: 2C
Operating Temperature: -20°C~60°C
Production Capacity:
Daily Output: 220,000 PCS
Lead Time: Samples in 1~3 days; mass production in 15~30 days
Certifications: UN38.3, MSDS, UL 1642, CE, IEC 62133, CB, BIS IS 16046, UKCA, PSE (Optional)
7. Summary
With surging global demand for clean energy and storage, the
21700 Battery lithium-ion cells market continues to expand. OEM manufacturers with robust process control, advanced equipment, and superior consistency are becoming essential partners for both upstream materials suppliers and downstream application brands. By optimizing every detail in manufacturing and logistics, we aim to deliver highly cost-effective, reliable 21700 Battery cell solutions tailored to customer needs.
