Gel Polymer Electrolyte Bonding for Low-Resistance Lithium Batteries
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Solution Overview
Problem
Lithium secondary batteries using gel polymer electrolytes face issues with electrode adhesion, leading to interface resistance and safety concerns, such as short circuits and reduced lifespan, due to low adhesion between the electrolyte and electrodes.
Innovation Solution
Incorporating a binder with an epoxy group or functional groups capable of ring-opening reactions in the electrode active material layer, which participates in the polymerization of the gel polymer electrolyte, enhancing adhesion and reducing interface resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a gel polymer electrolyte is used to prevent electrode degradation, then electrode stability is improved, but interface resistance increases due to poor adhesion
Solution Approach 1:
The coating layer acts as an intermediary that maintains electrode stability while ensuring low interface resistance. The binder in the coating layer creates strong interfacial bonds, preventing the electrode degradation issues associated with poor adhesion, while the coating layer itself provides a stable interface with the gel polymer electrolyte.
Solution Approach 2:
The interface properties are optimized by controlling the parameters of the coating layer, including binder content, coating thickness, and chemical composition. By adjusting these parameters, the interface resistance is minimized while maintaining the stability benefits of the gel polymer electrolyte system.
2Reliability
If a binder with epoxy group is incorporated to enhance adhesion, then adhesion is improved, but device complexity increases
Solution Approach 1:
The binder with epoxy group is incorporated locally in the coating layer at the electrode-electrolyte interface, rather than throughout the entire electrode structure. This localized approach improves adhesion where it is most needed while minimizing the increase in overall device complexity. The coating layer is a thin interface layer that does not significantly add to the device's overall 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
Improved adhesion between the gel polymer electrolyte and electrodes results in reduced internal short circuits, increased lifespan, and enhanced high-temperature safety of the battery.
Implementation Method 1
the oligomer and the binder comprise an epoxy group, a functional group capable of ring-opening reaction with an epoxy group, or a combination thereof
Implementation Method 2
a gel polymer electrolyte formed by polymerizing an oligomer
Data Source
AI summary
The present invention provides a lithium secondary battery including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and a gel polymer electrolyte formed by polymerizing an oligomer, wherein one or more electrodes selected from the positive electrode and the negative electrode includes an electrode current collector, an electrode active material layer formed on the electrode current collector, and a coating layer formed on the electrode active material layer and including a first binder, and the first binder is bonded to the gel polymer electrolyte, or a lithium secondary battery including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and a gel polymer electrolyte formed by polymerizing an oligomer, wherein an electrode active material layer of one or more electrodes selected from the positive electrode and the negative electrode includes a second binder bonded to the gel polymer electrolyte through an epoxy ring-opening reaction.