Sensitivity Analysis of Electrolyte Conductivity and Thickness in a PILBCP-Inspired Solid-State Lithium-Ion Battery

This project uses PyBaMM to compare a conventional lithium-ion battery model with a PILBCP-inspired solid polymer electrolyte/separator battery model.

The goal of the project is to identify which electrolyte/separator property most strongly controls the performance gap between the conventional control model and the PILBCP-inspired baseline.

The project was inspired by polymerized ionic liquid diblock copolymer (PILBCP) electrolyte/separator materials for lithium-ion batteries.

Project Overview

Conventional lithium-ion batteries usually use a liquid electrolyte and a porous separator. In solid polymer electrolyte batteries, the electrolyte can potentially serve both roles: allowing lithium-ion transport while physically separating the electrodes.

In this project, a conventional lithium-ion battery model was first simulated as the control case. Then, a PILBCP-inspired baseline was created by modifying two electrolyte/separator-related parameters:

• Electrolyte ionic conductivity
• Separator/electrolyte thickness

The electrode system, voltage limits, temperature, and operating conditions were kept unchanged so that performance differences could be mainly attributed to electrolyte/separator properties.

Research Question

Which solid electrolyte/separator property most strongly controls the performance gap between a conventional lithium-ion battery and a PILBCP-inspired solid polymer electrolyte battery?

Modeling Approach

The simulations were performed using:

• PyBaMM
• Doyle-Fuller-Newman (DFN) model
• Chen2020 parameter set
• Isothermal conditions at 298.15 K
• Discharge simulations at 0.1C, 0.5C, and 1C

The PILBCP-inspired baseline used:

• Separator/electrolyte thickness: 50 μm
• Electrolyte conductivity: 0.1 S/m

Two main parametric sweeps were performed:

1. Conductivity sweep

   Conductivity values:

   0.005, 0.01, 0.03, 0.1, 0.3, 1.0, 3.0 S/m
   

2. Thickness sweep

   Thickness values:

   25, 35, 50, 75, 100, 125 μm
   

Battery performance was evaluated using:

• Discharge capacity
• Average discharge voltage
• Discharge energy
• Energy difference relative to the conventional control
• Energy gap closure

Main Results

The PILBCP-inspired baseline performed similarly to the conventional control at low C-rate, but the performance gap increased at higher C-rate.

At 1C:

• The PILBCP-inspired baseline showed an 8.70% energy loss compared with the conventional control.
• Increasing conductivity from 0.1 S/m to 1.0 S/m recovered about 95% of the energy gap.
• Reducing thickness from 50 μm to 35 μm recovered about 12% of the energy gap.
• Reducing thickness more aggressively to 25 μm recovered about 19% of the energy gap.

These results suggest that electrolyte conductivity has a stronger effect on short-term battery performance than separator/electrolyte thickness over the tested design ranges.

Key Conclusion

The main conclusion of this project is that improving ionic conductivity should be prioritized over film thinning for PILBCP-inspired solid polymer electrolyte batteries.

Thickness is still important because thinner films reduce ion-transport distance. However, thickness cannot be reduced without limit because the solid electrolyte must also maintain mechanical stability and separator function.

Related literature suggests that ion chemistry, especially using FSI⁻ instead of TFSI⁻, may be a promising strategy for improving conductivity in PIL diblock copolymer electrolytes.

Requirements

This project uses Python with the following main packages:

pybamm
numpy
pandas
matplotlib
jupyter

Install the required packages with:

pip install -r requirements.txt

The requirements.txt file should contain:

pybamm
numpy
pandas
matplotlib
jupyter

How to Run

1. Clone the repository:

git clone https://github.com/calebhan0404/Sensitivity-Analysis-of-Electrolyte-Conductivity-and-Thickness-in-a-PILBCP-Inspired-Solid-State-Lith.git

2. Move into the repository folder:

cd Sensitivity-Analysis-of-Electrolyte-Conductivity-and-Thickness-in-a-PILBCP-Inspired-Solid-State-Lith

3. Install the required packages:

pip install -r requirements.txt

4. Open Jupyter Notebook:

jupyter notebook

5. Run the notebooks in order from the Notebooks/ folder:

01_control_group_conventional_battery.ipynb
02_pilbcp_inspired_baseline.ipynb
03_conductivity_sweep.ipynb
04_thickness_sweep.ipynb
05_energy_gap_closure_comparison.ipynb

Running the notebooks will generate the simulation outputs and figures used in the report.

Project Files

• Notebooks/ — PyBaMM simulations and parametric sweeps
• figures/ — compiled PDF of figures used in the report
• reports/ — final written project report
• REFERENCES.md — literature and software references
• requirements.txt — Python package requirements

Report

The full written report is available in the reports/ folder.

For literature and software references, see REFERENCES.md.

Notes

This project is not an exact reproduction of the experimental PILBCP battery from the literature. Instead, it is a controlled modeling study inspired by PILBCP solid electrolyte/separator materials.

The same electrode system and operating conditions were kept constant while electrolyte/separator properties were varied. This approach was used to isolate how electrolyte conductivity and separator/electrolyte thickness affect short-term simulated battery performance.