Pouch Battery Cell Seal Coating Against Anode-Edge Lithium Plating
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Solution Overview
Problem
Lithium plating occurs at the edges of anode electrodes due to torn anode tabs, leading to internal short circuits and electrolyte bridges in battery cells, which is a common issue during operation and assembly.
Innovation Solution
A seal coating is applied around the cathode and anode current collectors to prevent lithium plating, using a polymer coating that is enhanced by a pre-treatment coating like vinyl phosphoric acid (VPA) to improve bonding, and forming empty spaces for electrolyte reservoirs within the unit cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anode tabs are used for electrical connection, then current collection is improved, but lithium plating occurs at the edges leading to internal short circuits
Solution Approach 1:
A seal coating layer is introduced as an intermediary between the anode tab edge and the electrolyte/active material. This seal coating prevents direct contact that would otherwise lead to lithium plating, while still allowing the anode tab to perform its electrical connection function. The seal coating acts as a protective barrier that eliminates the harmful interaction without compromising the electrical connectivity.
Solution Approach 2:
The invention converts the potentially harmful exposed edge of the anode tab into a beneficial sealed structure. By applying the seal coating to the tab edges, the previously harmful feature (exposed edge causing lithium plating) is transformed into a protective feature that prevents lithium plating while maintaining electrical functionality.
2Reliability
If seal coating is applied around current collectors, then lithium plating is prevented, but manufacturing complexity increases
Solution Approach 1:
The seal coating is applied by modifying the coating parameters - specifically, applying a polymer coating at a controlled thickness (e.g., 1-10 micrometers) around the current collector edges. By controlling the coating parameters such as thickness, composition, and application method, the manufacturing process remains manageable while achieving effective lithium plating prevention.
Solution Approach 2:
The seal coating is applied locally only where needed - specifically at the edges of the current collectors where lithium plating occurs. This localized application approach minimizes the overall amount of coating material required and simplifies the manufacturing process compared to coating the entire current collector surface, while still providing effective protection at the critical locations.
3Strength
If pre-treatment coating is applied to enhance bonding, then seal coating adhesion is improved, but manufacturing steps increase
Solution Approach 1:
A pre-treatment coating layer is applied to the current collector surface before applying the seal coating. This preliminary action prepares the surface by improving its bonding characteristics, ensuring that the subsequent seal coating adheres strongly. The pre-treatment creates an optimized surface that facilitates strong bonding without requiring complex manufacturing procedures.
Solution Approach 2:
The invention uses a composite structure consisting of multiple coating layers: a pre-treatment coating layer (such as vinyl phosphoric acid or chromate) combined with a seal coating layer (polymer coating). This composite coating system leverages the complementary properties of different materials - the pre-treatment provides bonding enhancement while the seal coating provides the protective function, achieving strong adhesion through material composition rather than mechanical complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The seal coating prevents lithium plating and electrolyte bridges, enhancing battery safety and longevity by maintaining electrolyte levels and preventing dry-out, while utilizing low-cost materials and existing fabrication processes.
Implementation Method 1
A seal coating is applied around the cathode and anode current collectors to prevent lithium plating
Implementation Method 2
a pre-treatment coating like vinyl phosphoric acid (VPA) to improve bonding
Implementation Method 3
The seal coating comprises a polymer coating that is spaced from and around the cathode and anode active material layers
Data Source
AI summary
A method for manufacturing a battery cell comprising manufacturing C cathode electrodes by coating first and second cathode active material layers on opposite sides of C cathode current collectors, and applying first and second seal coatings on the C cathode current collectors to surround the first and second cathode active material layers, respectively. The method includes manufacturing A anode electrodes by coating first and second anode active material layers on opposite sides of A anode current collectors; and applying first and second seal coatings on the A anode current collectors to surround the first and second anode active material layers, respectively. The method includes arranging S separators between the C cathode electrodes and the A anode electrodes to form a battery cell stack, where C, A and S are integers greater than one.