Conductive Undercoating for Battery Current Collectors
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Solution Overview
Problem
Conventional conductive coating agents for battery current collectors are electrochemically decomposed and peeled off during long-term charging and discharging or high-temperature storage, leading to poor battery characteristics.
Innovation Solution
A conductive undercoating agent composition comprising a polymer with a silyl group, inorganic particles with active hydrogen groups, and a conductive agent, which forms a stable bond with the current collector, preventing electrochemical cleavage and enhancing adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conductive coating layer including a polymer compound incorporated as a binder is provided on the battery current collector, then the adhesion force between the current collector and the active material layer is improved, but the coating layer is electrochemically decomposed and peeled off during long-term charge/discharge cycles or high-temperature storage
Solution Approach 1:
The patent changes the chemical parameters of the binder by introducing a polymer with specific functional groups (carboxyl, hydroxyl, or amino groups) that can form strong chemical bonds with metal oxide surfaces. The polymer has a specific molecular weight range (10,000-1,000,000) and functional group content (0.1-10 mmol/g) to optimize both adhesion and electrochemical stability, resolving the contradiction between strong bonding and resistance to electrochemical decomposition
Solution Approach 2:
The patent creates a composite coating layer combining the polymer binder with metal oxide particles (such as alumina, silica, or titania) that exhibit high electrochemical stability. The metal oxide particles form stable bonds with the current collector while the polymer provides adhesion to the active material layer, achieving both strong adhesion and resistance to electrochemical decomposition through material composition
2Strength
If the adhesion force between the current collector and active material layer is enhanced, then the battery safety is improved, but the internal resistance remains high
Solution Approach 1:
The patent applies different functional components to different aspects of the coating layer: the polymer binder with specific functional groups provides strong local bonding at the interface between current collector and active material, while metal oxide particles provide local electrochemical stability and conductivity pathways. This localized functional distribution achieves both strong adhesion and low internal resistance without compromising either property
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 composition achieves high adhesion force and electrochemical stability, reducing internal resistance and preventing peeling, thus maintaining battery performance and reliability during long-term cycles and high-temperature exposure.
Implementation Method 1
the polymer has a silyl group of the formula -SiR11R12R13... a polymer having a substituent capable of bonding to an active hydrogen group
Implementation Method 2
to reduce the resistance at the interface between the battery current collector and the active material layer, thus improving the adhesion force
Data Source
Figure 1
AI summary
A task of the present invention is to solve the problem in that the conductive undercoating agent composition for coating a current collector has so poor electrochemical durability that the conductive undercoating agent composition is peeled off the current collector after a long-term reliability test. A conductive undercoating agent composition for a current collector for a battery or electrical double layer capacitor, which comprises a polymer having a substituent capable of bonding to an active hydrogen group, inorganic particles having an active hydrogen group, and a conductive agent.