A Systematic Guide to Lithium-Ion Battery Failure Analysis: Methods and Instrumentation

1. Overview: Why Lithium-Ion Battery Failure Analysis Matters

Lithium-ion batteries are a complex electrochemical system. As they become increasingly deployed in electric vehicles and grid-scale energy storage, the diversity of failure modes has grown correspondingly. Quantitatively analyzing battery failure to improve cell design and manufacturing processes is therefore a critical component of the R&D workflow.

Lithium-ion battery failure is broadly divided into two types. Performance failure includes capacity attenuation, capacity diving, abnormal rate performance, abnormal high/low-temperature performance, and poor cell consistency. Safety failure refers to incidents with safety risk arising from improper use or abuse—principally thermal runaway, gas evolution, leakage, lithium plating, short circuit, and expansion/deformation. The relationship between use conditions, failure mechanisms, and observed failure phenomena is summarized in Figure 1.^[1]

 

Figure 1. Lithium-ion battery failure modes — relationship between use conditions, failure mechanisms, and failure phenomena^[1]

As shown in Figure 2 ^[2], on the basis of the integrated and integrated system sub-platform of lithium-ion battery failure characterization-battery disassembly sample preparation/transfer/characterization, it is necessary to design a suitable lithium-ion failure analysis scheme for the specific failure phenomenon, and select the above mentioned suitable analysis and testing techniques for the material, electrode, and cell layers respectively, in order to efficiently and accurately obtain the cause of the lithium-ion battery failure. At the same time, it is also necessary to apply advanced testing and characterization and simulation techniques to the lithium-ion failure analysis, especially in-situ characterization and joint characterization techniques and devices. Advanced in-situ characterization techniques can help to deeply understand the reaction mechanism, structural evolution and interface evolution of the battery under the actual use conditions, and avoid the damage to the actual state of the battery after disassembling and testing.

Figure 2. System failure analysis method — integrated multi-level characterization workflow for battery cell failure analysis^[2]

IEST is a testing instrument supplier specializing in lithium-ion battery characterization. The failure analysis workflow described here integrates IEST instruments at each diagnostic level, from cell-level in-situ monitoring through material characterization.

The lithium-ion battery failure analysis process mainly consists of the following steps:

 

Figure 3. Lithium-ion battery failure analysis process — systematic workflow from cell-level diagnostics to material characterization

2. Level 1 — Battery Cell Failure Analysis (Non-Destructive)

Before disassembly, non-destructive analysis is performed on the failed cell to establish baseline electrical and dimensional data. The main steps are:

• Visual inspection and dimensional measurement. Adjust SOC (100% SOC for interface observation; 0% SOC for material analysis), photograph the cell, and record any damage, leakage, deformation, or gas production. Measure cell mass, thickness, and open-circuit voltage.
• Remaining capacity, DCR, and EIS testing. Cycle the failed cell at 0.33C or 1C in a 25 °C environment to determine remaining capacity (C_EOL). Conduct full-cell direct current resistance (DCR) and electrochemical impedance spectroscopy (EIS) tests to quantify changes in internal resistance before and after failure.
• In-situ swelling and gas evolution monitoring. Use the IEST SWE series in-situ swelling analyzer and GVM series in-situ gas-volume monitor simultaneously to track thickness change and volume change during charge-discharge after failure (Figure 4 and Figure 5). Comparing swelling behavior before and after failure reveals the contribution of irreversible gas accumulation and electrode deformation to the observed failure mode.

Figure 4. IEST GVM series in-situ gas production and volume test system — cell-level failure analysis tool for real-time gas evolution monitoring

Figure 5. IEST SWE series in-situ swelling testing system and principle — monitors thickness change for cell-level battery failure analysis

Figure 6. Application case: cyclic swelling data from battery failure analysis using SWE in-situ testing systems

Figure 7. Application case: gas evolution data from battery failure analysis using GVM in-situ systems

• Differential capacity (dQ/dV) analysis. Differential capacity is defined as the incremental charge per unit voltage change; peaks identify electrochemical phase transitions in electrode materials. Using a low charge/discharge rate (typically 0.04C) with high-frequency sampling (1 s intervals), dQ/dV and dV/dQ curves are generated. Combined with capacity and swelling data, peak shifts and intensity changes reveal cell polarization and active material loss.^[3]
• Tomographic analysis. X-ray computed tomography provides internal structural information—electrode dislocation, deformation, and separator shrinkage—without disassembly, establishing a reference for subsequent destructive analysis.

3. Level 2 — Interface and Electrolyte Failure Analysis

After completing all cell-level data collection, controlled disassembly begins. Cells are typically disassembled in two states: 100%/50% SOC (for interface characterization) and 0% SOC (for material analysis).

• Gas collection and GC analysis. Use a sealed gas collection bag to capture evolved gas during disassembly. Gas chromatography (GC) identifies species and quantifies concentrations. Characterizing the gas composition across the battery’s full life cycle is essential for revealing the interface reaction mechanisms and for improving safety and cycle life.
• Electrolyte extraction and analysis. After disassembling the 0% SOC cell, centrifuge the full jellyroll using the IEST electrolyte shake-off instrument (Figure 7)—which supports up to 280 Ah batteries—to extract inter-electrode electrolyte cleanly. IC, GC-MS, and ICP tests then quantify electrolyte consumption, additive degradation, and dissolved metal content.

Figure 8. Electrolyte centrifugation and consumption analysis process — supports cells up to 280 Ah for interface-level battery failure analysis

• Electrode interface characterization (100%/50% SOC). Record the interface conditions, electrode thickness, and positions using cameras and micrometers. Document black spots, lithium plating, stripes, coating delamination, and side-reactant layers. Key inspection points include: lithium precipitation on the anode surface, electrode peel strength, and the presence of metallic impurities, burrs, or foreign particles.

Lithium plating characterization requires monitoring the critical threshold at which plating is triggered and tracking its morphological evolution. Reduced peel strength is a common indicator of mechanical degradation: causes include repeated volume changes of the active material, binder failure from thermal stress, and current collector surface corrosion. Foreign particles pose a direct safety risk—they may pierce the separator or dissolve into the electrolyte and deposit as metal dendrites, causing micro-short circuits and self-discharge.

4. Level 3 — Material Hierarchy Failure Analysis

After all data collection for the electrolyte and interface is completed, material level analysis begins. At this time, different test items can be analyzed using different SOC electrodes. Different testing items require different pre-treatments. Some materials that are greatly affected by the electrolyte need to be soaked and cleaned in DMC before other tests are performed. The main analysis processes at the material level are as follows:

4.1 Analysis at 100% SOC

• Symmetric cell impedance and tortuosity analysis. Symmetrical cell EIS decomposes electrode impedance into ohmic resistance, membrane void structure impedance, ion transport impedance, and diffusion impedance. This isolates the source of resistance growth during the failure process. The IEST multi-channel ion conductivity tester enables rapid symmetric cell assembly, simultaneous EIS measurement, and electrode tortuosity testing.

Figure 9. IEST multi-channel ion conductivity testing system and Nyquist diagram of symmetric cells — impedance decomposition for material-level failure diagnosis

• Electrode Resistance Testing. The IEST BER series electrode resistance tester can be used to quickly test the electrode electronic resistance and analyze the source of growth in battery assembly. Due to the high-precision thickness sensor and pressure sensor, the pressure and resistance changes of the electrode can be tested in real time. The application case is shown in Figure 10. The black line is the \(R_s\) value of the electrode symmetrical battery, and the blue line is the electrode resistance \(R_e\) value. The growth rules of \(R_s\) and \(R_e\) are consistent, but the sources of resistance growth of the two are different during high temperature cycling and high temperature storage, showing that their failure modes are different.

Figure 10. Electrode resistance testing principle and IEST BER series instruments

Figure 11. Rs (symmetric cell impedance) and Re (electrode resistance) changes during high-temperature cycling and storage — divergent profiles indicate different failure mechanisms

• Material thermal stability analysis. Powder scraped from fully charged electrode plates is analyzed by TG-DSC to characterize thermal stability changes before and after failure. This is particularly important for cathode materials where thermal decomposition onset temperature is a key safety indicator.

4.2 Analysis at 0% SOC

• Capacity analysis. Single-side electrodes are assembled into half-cells (coin cells) and cycled for gram capacity measurement, quantifying remaining reversible capacity. Combined with full-cell dQ/dV analysis, this distinguishes lithium loss from polarization loss as the dominant degradation mechanism.^[4]
• Active surface area. CV-based analysis of electrochemically active surface area provides a quantitative indicator of material side reactions and SEI growth.
• Porosity testing. True-density method (preferred over mercury intrusion due to toxicity concerns) quantifies electrode porosity changes that contribute to ion transport resistance increases.
• Morphology and surface element analysis. CP-SEM-EDS characterizes material morphology (expansion, agglomeration, fragmentation, side-reactant accumulation) and surface elemental changes. For silicon anodes, the RSS (Rapid Swelling Screening) system and CP-SEM provide complementary data: the IEST silicon anode swelling rapid screening system (Figure 12) quantifies swelling magnitude under cycling conditions, while CP-SEM reveals the actual electrode thickness distribution after different processing routes (Figure 13).

Figure 12. Coulombic Swelling Testing System and Silicon Anode Swelling Rapid Screening System

Figure 13. Swelling variations of different silicon anode materials and actual electrode thickness — comparison between RSS Series screening and CP-SEM cross-section measurements

• Crystal and molecular structure analysis. XPS, NMR, Raman, XRD, TEM, and FTIR characterize crystal structure and surface molecular structure changes before and after failure. Combined with impedance analysis, these techniques enable precise failure source attribution.^[4]
• Elemental analysis. ICP analysis of cathode, anode, separator, and electrolyte samples determines element distribution changes—particularly useful for identifying coating failure and transition metal dissolution events that otherwise produce subtle electrochemical signatures.

5. Summary

Effective lithium-ion battery failure analysis requires a structured, multi-level approach. Cell-level non-destructive testing establishes the failure signature through electrical and dimensional data; interface-level analysis after disassembly identifies electrolyte degradation, lithium plating, and coating delamination; material-level characterization pinpoints the root cause—whether capacity loss, resistance growth, or structural degradation—using advanced spectroscopic and electrochemical techniques.

IEST instruments support this workflow at each level: GVM and SWE series for in-situ gas and swelling monitoring, the BER series for electrode resistance, and the ion conductivity tester for symmetric cell EIS and tortuosity. As lithium-ion battery applications expand into larger formats and more demanding duty cycles, the systematic battery failure analysis methodology described here becomes increasingly important for improving product consistency, reliability, and safety across the industry.

6. References

[1] Wang Qiyu, Wang Shuo, et al., Overview of Lithium-ion Battery Failure Analysis, Energy Storage Science and Technology, 2017, Vol5, No.15

[2] Wang Yi, Chen Xuebing, Wang Yuanxi, et al. Review of multi-level failure mechanism and analysis technology of energy storage lithium-ion batteries [J]. Energy Storage Science and Technology, 2023, 12(7):2079-2094.

[3] Dr. Kun, Li Xiang Life Public Account: Lithium-ion Battery Disassembly Failure Analysis Method, 2023-06-22

[4] Fang Chenxu, Research on the performance failure mechanism of long-term energy storage batteries, New Material Application and Characterization Technology (Xiamen) Exchange Conference, 2023

[5] Wei Liying, Failure Analysis of Key Materials in Li-ion Batteries, New Material Application and Characterization Technology (Xiamen) Exchange Conference, 2023

7. FAQs