Battery Performance Testing | Summary of Electrical Performance Test Items for Lithium-Ion Batteries
In the R&D, production, and outgoing quality inspection of lithium-ion batteries, electrical performance testing is one of the most fundamental components of quality evaluation. It is directly related to capacity delivery, cycle life, charge–discharge efficiency, and stability under different temperature conditions. This article comprehensively summarizes the electrical performance test items for polymer lithium-ion cells and batteries and, in conjunction with industry standards and practical testing specifications, delves into the purpose, methods, and judgment criteria of each test.
1、Overview of Electrical Performance Test Items
According to industry standards and enterprise testing specifications, common electrical performance test items include:
| No. | Test Item | Test Purpose | Judgment Criteria (Summary) |
|---|---|---|---|
|
1 |
Appearance, dimensions, weight, internal resistance |
Screen for appearance defects; verify installation dimensions and weight; check IR consistency |
Per specification/drawing standards |
|
2 |
Rate capability test |
Evaluate capacity delivery under different discharge rates |
Per specification/drawing standards |
|
3 |
Cycle life test |
Assess cycle fade and usable lifetime |
Number of cycles not fewer than 300 |
|
4 |
High-temperature discharge performance |
Verify capacity retention at high temperature |
Per specification standards |
|
5 |
Low-temperature discharge performance |
Verify discharge capability at low temperature |
Per specification standards |
|
6 |
Pulse discharge test |
Evaluate the battery’s pulse load capability |
Per specification standards |
|
7 |
Evaluation of excess lithium deposition |
Identify post-cycling lithium plating/internal short risks |
After teardown, the anode interface should appear golden-yellow with no visible lithium plating |
2、Detailed Explanations of Electrical Performance Test Items
2.1 Appearance, Dimensions, Weight, and Internal Resistance Test
Test Purpose:
Verify whether the cell or battery surface has scratches, defects, cracks, electrolyte leakage, and other issues that could affect normal performance, as well as whether weight and internal resistance meet requirements; verify whether the cell or battery dimensions satisfy the customer’s installation-size requirements.
Test Steps:
Appearance: Perform inspection under normal lighting or outdoor natural light, simulating the final use condition (eyes 30–50 cm from the object).
Dimensions: Use a vernier caliper to measure the battery’s thickness, width, height, and diameter (test per the standard drawing in Appendix 1).
Weight: Weigh with an electronic scale and record the battery weight.
Internal resistance: Connect the battery’s positive and negative terminals to the tester’s positive and negative terminals, respectively; when the displayed internal resistance stabilizes for 3 s, take it as the standard internal resistance.
Judgment Criteria:
Per specification/customer drawing standards; no leakage/swelling/cracks in appearance; dimensions and weight within tolerance; internal resistance not higher than the maximum value specified in the specification.
Figure 1. Dimensional Measurement Standard Schematic
2.2 Capacity Ratio Test
Test Purpose:
Evaluate the cell’s discharge performance at different discharge currents.
Test Steps:
① Discharge at 0.5C to 3.0 V, then rest for 10 min;
② Charge at 0.5C (use 1.0C for high-rate cells) to full, then rest for 10 min;
③ Discharge at 0.5C (use 1.0C for high-rate cells) to 3.0 V, record the discharge capacity A, then rest for 10 min;
④ Charge at 0.5C (use 1.0C for high-rate cells) to full, then rest for 10 min;
For high-rate cells, continue testing as follows (conventional capacity-type cells only perform ①–④):
⑤ Discharge at 10C to 3.0 V, record the discharge capacity B, then rest for 10 min;
⑥ Charge at 1.0C to full, then rest for 10 min;
⑦ Discharge at the maximum discharge current committed in the specification to 3.0 V, and record the discharge capacity C;
⑧ Capacity ratio calculation is as shown in Table 1 below:
Table 1. Capacity Ratio Calculation and Standards
Note: For conventional capacity-type cells, perform a 2C discharge test; the 2C capacity is for reference only.
Judgment Criteria:
Follow the standards in Table 1.
2.3 Cycle Life Test
Test Purpose:
Evaluate the cycle life performance of the cell or battery.
Test Steps:
Iray Energy standard:
① Rest for 10 min;
② Charge at 0.5C (use 1.0C for high-rate batteries) to full;
③ Rest for 10 min;
④ Discharge at 0.5C (for high-rate batteries, discharge at the maximum discharge current committed in the specification) to 3.0 V;
⑤ Repeat steps ①–④;
⑥ Record the battery’s discharge capacity every 50 cycles;
⑦ When the discharge capacity is lower than 80% of the initial discharge capacity for 3 consecutive times, the test can be stopped.
GB/T 18287 standard:
① At room temperature, charge at 1.0C constant current to 4.2 V, then switch to constant voltage charging until the current is less than or equal to 20 mA, then stop charging;
② Rest for 0.5 h–1 h;
③ Perform the next charge–discharge cycle until the discharge time is less than 36 min for two consecutive cycles, at which point the life is considered to have ended.
Judgment Criteria:
The number of cycles of the cell or battery shall be no fewer than 300, and the capacity retention shall be 80% or above.
2.4 High-Temperature (55 °C) Discharge Performance Test
Test Purpose:
Evaluate the discharge performance of the cell or battery under high-temperature conditions.
Test Steps:
① Charge at 0.5C (use 1.0C for high-rate batteries) to full, then rest for 10 min;
② Discharge at 0.5C (use 1.0C for high-rate batteries) to 3.0 V and record the discharge capacity A, then rest for 10 min;
③ Charge at 0.5C (use 1.0C for high-rate batteries) to full, then rest for 10 min;
④ Place the fully charged cell in a chamber at 55 ± 2 °C for 2 hours, then discharge at 0.5C (use 1.0C for high-rate batteries) to 3.0 V and record the discharge capacity B.
Judgment Criteria:
B/A ≥ 85%; no deformation in appearance; no explosion; no cracks.
2.5 Low-Temperature Discharge Performance Test (covering −20 °C / −10 °C / 0 °C)
Test Purpose:
Evaluate the discharge performance of the cell or battery under low-temperature conditions.
Test Steps:
① Charge at 0.5C (use 1.0C for high-rate batteries) to full, then rest for 10 min;
② For each temperature point, place the test sample at the target temperature for 4 h, then discharge at 0.2C to 3.0 V and record the capacity data;
③ After completing one temperature experiment, place the battery at room temperature for 4 h, then charge to full per step ①;
④ The discharge capacity ratio (%) at different temperatures is based on the discharge capacity at 25 °C.
Table 2. Discharge Capacity Ratio (%)
Judgment Criteria:
Follow the standards in Table 2.
Note: Test sequence: 25 °C → −20 °C → −10 °C → 0 °C.
2.6 Pulse Discharge Test
Test Purpose:
Simulate and analyze the performance of the cell or battery discharging with a certain rhythm.
Test Steps:
① Charge at 1.0C constant current to 4.2 V, then switch to constant voltage charging until the current drops to 0.02C; rest for 10 min;
② Discharge at the maximum pulse current A for the specified time T (T is the pulse duration) to 3.0 V; rest for 10 min;
③ Set the pulse cause-and-effect step; if the discharge cutoff voltage is greater than 3.0 V, then the step jumps to step ②.
Judgment Criteria:
Execute per the specification requirements.
2.7 Evaluation of Excess Lithium-Ion Deposition (Lithium Plating Evaluation)
Test Purpose:
Detect lithium plating and short-circuit conditions after cycling.
Test Steps:
① Fully discharge the sample to 3.0 V at 0.5C;
② At ambient temperature, cycle the sample 25 times with 1.0C charge–discharge; after cycling, charge the cell to full at 1.0C;
③ Dissect the fully charged cell after cycling and observe the separator and the anode electrode interface.
Judgment Criteria:
After cycling, the dissected sample’s anode interface should appear golden with no lithium plating.
3、Referenced Standards and Applicable Specifications
UL1642
UL2054
IEC62133
GB/T 18287
UN38.3
Certain customer-specific standards
4、Summary and Recommendations
The lithium-ion battery production process involves numerous steps, and electrical performance testing is the core gatekeeping stage that directly determines capacity delivery, consistency, and safety margin. It is recommended to advance electrical performance testing into R&D and pilot runs, and have it run through incoming materials, in-process control, and final inspection; unify boundary conditions and judgment criteria, establish SPC and a closed data loop, and use test results to drive material and process optimization to reduce failure risk. Pay particular attention to high- and low-temperature as well as pulse operating conditions, and verify using a temperature/rate matrix set according to the application.
