Cross-Linked Anode Binder for Dendrite-Resistant Lithium Batteries
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Solution Overview
Problem
Lithium batteries face issues with the formation of dendrites, poor initial efficiency, and electrode stability due to the use of protective layers that are thick, leading to increased current density and unstable solid electrolyte interphase (SEI) formation.
Innovation Solution
A binder is developed using a cross-linked polymer of fluorine-substituted polyamic acid or polyimide with a water-soluble polymer, forming a protective layer on the anode current collector, which inhibits volume change and enhances electrode stability through an ester bond cross-linking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of a protective layer is increased to obtain sufficient ionic conductivity, then ionic conductivity is improved, but the current density of a lithium battery increases
Solution Approach 1:
The patent changes the chemical composition parameters of the protective layer by incorporating fluorinated polymers and conducting polymers in specific ratios, allowing the layer to achieve sufficient ionic conductivity at reduced thickness. The fluorinated polymer component modifies the ionic transport properties, enabling thinner layers to maintain high ionic conductivity while reducing overall current density
Solution Approach 2:
The protective layer is designed as a composite material combining fluorinated polymer, conducting polymer, and binder in optimized proportions. This composite structure synergistically improves ionic conductivity while maintaining mechanical integrity and reducing thickness, thereby resolving the contradiction between ionic conductivity and current density
2Stability of the object's composition
If a hybrid binder of polyimide and polyvinyl alcohol is applied to a protective layer, then structural stability is improved, but a stable solid electrolyte interphase (SEI) is not easily formed during initial plating
Solution Approach 1:
The patent modifies the chemical parameters of the protective layer by introducing fluorinated polymer components with specific functional groups that promote stable SEI formation. The fluorinated groups alter the electrochemical properties at the electrode interface, enabling stable SEI formation while maintaining the structural stability provided by the polyimide-polyvinyl alcohol hybrid binder
3Stability of the object's composition
If a protective layer is used to inhibit dendrite formation, then electrode stability is improved, but volume change of the electrode and binder increases
Solution Approach 1:
The patent employs a thin film protective layer design that provides dendrite inhibition and electrode stability without significant volume change. The flexible yet stable polymer matrix accommodates minor volume fluctuations while maintaining overall structural integrity, preventing the binder from undergoing excessive volume changes during battery cycling
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 binder improves initial efficiency, lifespan characteristics, and electrode stability by inhibiting volume change, while maintaining effective ion flux and reducing dendrite formation.
Implementation Method 1
the first polymer is cross-linked to the second polymer by an ester bond formed via a reaction between the first functional group and the second functional group
Implementation Method 2
a binder including a third polymer as a cross-linked product of a first polymer and a water-soluble second polymer
Data Source
Figure 1~2
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AI summary
Provided are a binder, an anode comprising a protective layer including the binder, and lithium battery comprising the anode, wherein the binder comprises a third polymer that is product of a cross-linking reaction between one or more first polymers comprising a first functional group and being selected from among fluorine-substituted poly(amic acid) and fluorine-substituted polyimide and a second polymer comprising a second functional group and being water soluble, wherein the first polymer and the second polymer are cross-linked by forming an ester bond through a reaction between the first functional group and the second functional group.