Description
Critical Challenges in Battery Manufacturing, Usage & Recycling
From production-line inconsistency to end-of-life assessment — six key pain points across the battery life cycle
Battery Manufacturers
Challenges in production and quality control
Q1Production Screening
Higher-capacity cells have lower internal resistance — conventional electrochemical workstations lack resolution for accurate measurement, while external current boosters are prohibitively expensive.
Q2Batch Sorting
OCV or 1 kHz ACIR alone cannot distinguish subtle variances between cell batches. How can we achieve refined, high-precision sorting?
Q3Failure Analysis
When abnormal cells emerge, how can production defects be rapidly pinpointed — welding defects, formation issues, or active material degradation?
Battery End-Users & Recyclers
Challenges in deployment, reuse, and second-life applications
Q4Module Consistency
Prior to assembling battery modules, how can cell consistency be reliably evaluated? Relying merely on OCV or 1 kHz ACIR is no longer sufficient.
Q5Supplier Variability
Do latent performance differences exist between nominally identical cells from different vendors, and can they be safely mixed in the same pack?
Q6Second-Life SOH
For retired or disassembled cells, what is the remaining State of Health (SOH)? How can they be accurately graded for second-life cascading utilization?
⚡ From production-line screening to end-of-life assessment — precision electrochemical testing is the essential link across the entire battery life cycle.
In new energy vehicles or energy storage power stations, lithium batteries are often used in the form of multiple paralel modules or packs. Therefore, high consistency requirements are placed on the battery cells in the same module or pack. Otherwise, thermal runaway may occur easily due to overcharging/overdischarging of a certain battery cell, leading to many after-sales problems.
Electrochemical impedance spectroscopy (EIS) has good sensitivity and correlation with the SOC, SOH, internal temperature, internal short circuit, etc, of the battery celll. By usine fast EIS testing and neural network algorithm modeling, you can effectively screen the consistency othe battery cells and help the cascade utilization of the battery cells.
2. Application
3. IEST Creative Solutions
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Electrochemical Impedance Spectroscopy (EIS) is a characterization technique that treats the battery cell as a “black box,” applying voltage and current perturbations across different frequencies while collecting the corresponding response signals to quantify the resistance and impedance of electrochemical processes with distinct time constants.
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Introducing EIS testing prior to cell shipment or during incoming inspection—and comparing impedance variances among cells—enables: (1) screening cell-to-cell consistency; (2) identifying anomalous cells; and (3) unraveling cell failure mechanisms!
3. BIT6000 Introduction
Functions & Features:
- Fast EIS Frequency Sweep Testing: Executes rapid, multi-channel coupled electrochemical impedance spectroscopy(EIS) across a wide 1500 Hz to 0.1 Hz frequency range, executing high-speed cell grading without compromising spectral data integrity.
- Ultra-Wide Capacity Envelope: Universally calibrated to evaluate massive cell spectrums scaling from 1 Ah to 1000 Ah, effortlessly optimizing sorting workflows for large-scale power batteries and high-capacity grid storage modules.
- Dynamic Multi-Parameter Fitting: Employs advanced internal algorithms for real-time mathematical curve fitting during batch battery consistency screening , enabling high-precision rapid compartmentalization and abnormal cell detection.
- Unified Multi-Modal Characterization: Combines high-accuracy Open Circuit Voltage (OCV) profiling, Direct Current Internal Resistance (DCR) evaluation, and continuous constant-current testing parameters into a centralized automated testing sequence.
Applications
1. Application Scenario
2. ElS Test of Battery With Large Capacity & Low Internal Resistance.
IEST BIT6000 can easily test the EIS of batteries with large capacity (2Ah~1000Ah) and low internal resistance (0.05mΩ~100mΩ). We also support customization various testing fixtures and automation testing equipment.
Note: The EIS test frequency range can be adjusted according to the production line progress and process section
3. EIS Testing During Battery Cycling
- IEST BIT6000 can be integrated with any cycler. Users can first use the cycler tester to perform the cyclic aging on the battery, and BIT6000 can automatically perform the EIS testing under different SOH states, which can save the switching time between ”temperature adiustment ⇔ charge and discharge instrument ⇔ electrochemical workstation”
- IEST BIT6000 can also perform the EIS testing during the charging & discharging process, i.e., dynamic EIS or operando EIS.
4. Battery Cell Failure Analysis (Production Troubleshooting)
Distribution of Relaxation Times (DRT) analysis is a mathematical method for interpreting EIS spectra. Unlike conventional Equivalent Circuit Model (ECM) fitting, DRT analysis eliminates common issues such as: ① dependency on initial parameter values; ② fitting distortion; and ③ ambiguous mechanistic interpretations when multiple distinct models can fit the same data.
Distribution of Relaxation Times (DRT) analysis is a mathematical method for interpreting EIS spectra. Unlike conventional Equivalent Circuit Model (ECM) fitting, DRT analysis eliminates common issues such as:
- Dependency on initial parameter values.
- Fitting distortion.
- Ambiguous mechanistic interpretations when multiple distinct models can fit the same data.
5. Battery Consistency Sorting (Abnormal Cell Screening)
- For battery manufacturers producing and assembling modules/packs, EIS testing can be used to check the quality and consistency of battery in the same module/pack.
- For EV/energy-storage manufacturers sourcing batteries externally, EIS testing ensures incoming battery quality to maintain the consistency of battery in the same module/pack.
6. Rapid SOH Estimation (Cascade Utilization)
6.1 Traditional Battery Capacity Grading & Cascade Utilization
- A batch of recycled / retired batteries
- Perform charge-discharge cycling on batteries
- Group and sort batteries based on measured capacity for cascade utilization
Three Major Limitations:
- A batch of recycled batteries
- Perform charge-discharge cycling on batteries
- Group and sort batteries based on measured capacity for cascade utilization
6.2 IEST Rapid Capacity Grading Solution:
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A batch of recycled batteries
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Perform EIS testing on batteries
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Execute rapid capacity grading based on EIS-capacity correlation models
As the State of Health (SOH) decreases, the battery EIS impedance response changes accordingly.
6.3 EIS-Based Rapid SOH Estimation Model
SOH Estimation Accuracy<5% (Big Data Modeling Required)
7. Case
7.1 EIS screening is conducted on 30 prismatic cells with a capacity of 50Ah each (at 50% state of charge) over a frequency range from 1500Hz to 0.1Hz.
Especially for the battery represented by the green line, its impedancein the high-frequency region is consistent with other batteries, and only the impedance in the medium and low-frequency regions has a large difference. In this case, if only the electronic resistance or 1000Hz impedance is tested, it cannot be effectively distinguished, but swept frequency EIS can effectively screen and identify!
7.2 EIS screening is conducted on 40 cylindrical cells with a capacity of 30Ah each (at 6.5% state of charge) over a frequency range from 1500Hz to 0.1Hz.
In zone Ⅰ: For ohmic impedance and SEI impedance, the 30 batteries are distributed relatively concentratedly, with no obvious differences; In zone Ⅱ: Rct is divided into two concentrated areas, indicating that there are certain differences in the ionic impedance of the 40 batteries, which will affect the capacity after long cycles
Specifications
| Category | Battery Impedance Tester | Adjustable Prismatic Cell Fixture | Adjustable Cylindrical Cell Fixture |
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| Product Image |  |
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| Model | BIT6000 | APTB1000 | ACTB1000 |
| Current Excitation Range | 0.01 ~ 10A |
Suitable for various prismatic cells
Max L × W × H:
284 × 94 × 255 mm Tab Pitch:
40 ~ 240 mm (Custom dimensions supported)
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Suitable for 18650 / 21700 and other cylindrical cells
Max Length:
130 mm Diameter Range:
18 ~ 50 mm (Custom dimensions supported)
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| Current Control Accuracy | ±0.05% F.S. | ||
| Voltage Test Range | 0 ~ 5V | ||
| Voltage Control Accuracy | ±0.006% F.S. | ||
| EIS Frequency Range | 20 kHz ~ 0.01 Hz | ||
| Applicable Internal Resistance | 0.05 mΩ ~ 5 mΩ | ||
| Compatible Battery Capacity | 3 ~ 1000 Ah Li-ion Batteries | ||
| Specifications |
Dimensions (W×D×H):
412 × 180 × 300 mm Weight: 11 kg
Rated Power: 1200 W
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Dimensions (W×D×H):
350 × 310 × 522 mm Weight: 7.5 kg
Max Probe Current: 30A
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Dimensions (W×D×H):
474 × 100 × 143 mm Weight: 3 kg
Max Probe Current: 30A
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IEST Battery Consistency & Battery Impedance Tester
