IEST Instruments
Industrial-Grade Battery Impedance Testing & Application Solutions
IEST Battery Impedance Tester BIT6000
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ElS Test for Large-capacity Batteries (Single & Cycle test)
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Battery Consistency Screening (Abnormal Battery Screening) -
SOH Rapid Estimation(Cascade Utilization) -
Battery Failure Analysis (Production Problem Troubleshooting)
Lithium Battery Industry Pain Points
Battery Manufacturers
Q1: The larger the battery capacity, the smaller the internal resistance. Traditional electrochemical workstations cannot perform effective testing and they are expensive if used with current amplifiers.
Q2: Diferent batteries can't be distinguished by OCV or 1000Hz AClR alone. How can the batteries be sorted more finely?
Q3: lf there is an abnormality in the battery, how can we quickly locate the production problem? is it a poor welding? Or a poor formation? Or is it a material failure?
Battery Use & Recycling Companies
Q1: How to judge the battery consistency before assembling the battery module? Relying solely on OCV or 1000Hz ACIR is no longer sufficient.
Q2: Are there diferences between the same type of batteries purchased from different manufacturers? Can they be mixed?
Q3: For recycled or disassembled batteries, what is the remaining SOH (State of Health), and how can they be utilized in echelon applications?
Innovative Solutions of IEST
- Electrochemical Impedance Spectroscopy (EIS) is a method that treats a battery cell as a "black box," applies voltage or current perturbations at varying frequencies, collects the corresponding response signals, and characterizes the impedance magnitudes of electrochemical processes with different time constants.
- Introducing EIS testing before battery shipment or upon incoming material inspection, and comparing impedance variations between cells, enables:
1) Screening battery consistency.
2) Identifying abnormal cells.
3) Assisting in analyzing cell failure mechanisms!
BIT6000 Introduction
Functions & Features:
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Wide range of applicable cells, ranging from 1Ah to 500Ah
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Fast EIS frequency sweep testing, with a frequency rangeof 1500Hz~0.1Hz;
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Equipped with OCV testing, DCR testing, constant current charge-discharge testing, etc.
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Battery Consistency Screening.
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Dynamic fitting screening algorithm for batch screening.
Application Scenario.
Battery Recycling & Cascade Utilization
Battery Pack After-Sales Center
Used Car Recycling
ElS Test of Battery With Large Capacity & Low Internal Resistance.
ElS Test for 280Ah LFP Battery(1500 Hz~0.1 HZ)
Frequency vs. Total Test Time
Support Customization of Various Test Lines or Fixtures
The EIS test frequency range can be adjusted according to the production line progress and process section
EIS Test During Battery Cycling.
Coin cell Cycle EIS Test: 0.01Hz~100kHz, EIS test every 10% SOC
Save the switching time between ”temperature adiustment ←→ charge and discharge instrument ←→ electrochemical workstation”
Battery Consistency Screening (Abnormal Battery Screening).
Traditional Battery Sorting Method
lEST's Innovative Battery Sorting Method
Using EIS (Electrochemical Impedance Spectroscopy) for refined screening of batteries ensures charge-discharge consistency across all individual cells within a battery module.
SOH Rapid Estimation (Cascade Utilization).
Traditional battery grading and cascade utilization:
- A batch of recycled batteries
- Charge and discharge the batteries
- Grouping and tiered utilization based on capacity
Three Major Disadvantages:
- Long grading time
- High power consumption
- Many channels occupied
IEST’s Rapid Grading Solution:
- A batch of recycled batteries
- Perform ElS test on the batteries
- According to the correlation model between ElS and capacity, conduct rapid capacity division
Major Advantages:
As the battery health (SOH) decreases, its EIS test results will also change accordingly.
SOH Estimation Accuracy<5% (Big Data Modeling Required)
Battery Cell Failure Analysis (Production Problem Troubleshooting).
Distribution of Relaxation Times (DRT) analysis is a mathematical method for interpreting EIS spectra. Unlike conventional equivalent circuit fitting, DRT analysis can avoid issues such as:
- The fitting model’s dependence on initial values;
- Distortion of the fitting results;
- The fact that while different models can be fitted, their mechanistic interpretations are inconsistent.
- Contact Impedance Rs: The total sum of all electronic resistances within the battery, which is associated with various issues.
- Contact Impedance Rc ⇔ Area 1: Problems such as poorly welded tabs and inadequate contact.
- SEI Film Impedance RSEI ⇔ Area 2: Issues including improper formation and electrode creasing or wrinkling.
- Charge Transfer Impedance Rct ⇔ Area 3: Problems related to poor interfacial kinetics and lithium plating.
- Ionic Diffusion Impedance Rdiff ⇔ Area 4: Issues such as insufficient electrode compression and inadequate electrolyte wetting.
