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Improving Battery Formation Protocols with Tescan Post-Mortem Characterization

Plasma FIB-SEM and ToF-SIMS analysis of the SEI formation reveals how cycling protocols impact capacity retention and long-term battery performance.

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How Formation Shapes Battery Lifespan and What Happens When It Fails 

Battery cell formation — the first controlled charge–discharge cycle — sets the stage for long-term performance. It also defines the properties of the Solid Electrolyte Interphase (SEI), a protective layer critical for stability and capacity retention.

Formation is often time-consuming and expensive, and the impact of different protocols can be difficult to evaluate. In this study, post-mortem analysis of three graphite–LFP cells using Tescan AMBER X 2 Plasma FIB-SEM, EDS, ToF-SIMS, and RSTEM revealed how formation choices influence surface morphology, elemental composition, and interfacial stability. These insights help battery developers shorten development cycles and improve formation efficiency.

Why Analyze Formation Protocols

with TESCAN

01
Root of the Problem

Why SEI Quality Depends on the Formation Process

The SEI layer forms during the first few cycles of a lithium-ion battery’s life. Its properties — thickness, homogeneity, chemical composition — directly affect cycle stability, Coulombic efficiency, and internal resistance. If the SEI is too fragile or uneven, lithium plating, graphite degradation, or excess side reactions may occur.

Different formation protocols (voltage windows, current densities, rest periods) influence how this layer develops. But without visual and chemical inspection, these effects can go unnoticed until performance drops. Post-mortem analysis provides a way to connect formation parameters with actual physical changes at the electrode surface.

02
Materials and Methods

Inert Handling, FIB Milling, and Multimodal Analysis

Three lithium-ion cells — identical in electrode chemistry (LFP cathode, graphite anode) — were formed using three different charge/discharge profiles. After 1000 cycles, they were disassembled in an argon glovebox. Graphite anode sections were transferred to the Tescan AMBER X 2 system via an inert gas transfer system.

Each sample underwent SEM imaging, EDS mapping, and ToF-SIMS elemental profiling of the SEI. Then, FIB-milled lamellae were prepared for RSTEM analysis, allowing cross-sectional imaging of internal SEI structure. Comparative datasets were collected for each formation protocol to assess differences in morphology and chemistry.

03
Results and Discussion

Surface Morphology, Fluorine Infiltration, and Capacity Loss

Visual comparison between the best- and worst-performing samples showed clear differences. Sample 1 (low-capacity retention) exhibited rougher surface morphology, greater fluorine presence, and signs of excessive side reactions. ToF-SIMS mapping detected higher fluorine signals in the SEI, suggesting instability or overreaction with electrolyte components.

In contrast, Sample 3 (highest capacity retention) showed a more uniform SEI, lower fluorine infiltration, and clearer lamella structure in STEM imaging. Elemental depth profiling highlighted better-controlled oxygen and fluorine distributions. These findings directly correlate SEI quality with formation protocols — offering manufacturers a path toward more efficient and stable battery designs.

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Tescan Instruments & Technology

Used in This Workflow

Tescan AMBER X 2

TESCAN AMBER X 2 enables correlative structural and chemical analysis of lithium-ion battery components — ideal for SEI inspection, lamella preparation, and advanced degradation studies.

  • Plasma FIB for fast lamella milling and volume sectioning

  • Field-free UHR SEM with low-kV imaging for surface-sensitive features

  • Integrated RSTEM for nanometer-scale subsurface analysis

  • Compatible with inert sample transfer workflows 

 

AMBER-X2

ToF-SIMS Module – High-Sensitivity Surface Chemistry Mapping

The integrated ToF-SIMS system allows for detection and spatial mapping of key battery-relevant elements including Li, F, O, and P. 

  • Elemental and isotopic mapping of surface and subsurface regions

  • Correlation with SEM/EDS for complete morphology-chemical context

  • Excellent for analyzing SEI composition and cycling-induced changes 

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Where can you find us: 

Tescan Brno
Libušina třída 21
623 00 Brno
Czech Republic

info@Tescan.com