Composite Binder for Self-Extinguishing Li-Ion Battery
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Solution Overview
Problem
Lithium ion batteries face frequent safety issues due to their high risk of combustion, which compromises their safety performance without affecting their electrochemical performance and structural stability.
Innovation Solution
A composite binder is developed by mixing ammonium polyphosphate and polyacrylic acid, followed by thermal treatment, to create a self-extinguishing lithium ion battery with enhanced flame retardancy, electrochemical performance, and structural stability, utilizing the synergistic effects of non-volatile phosphorus oxide and polyphosphoric acid to form a stable SEI film and improve mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binders are used in lithium ion batteries, then the battery can be manufactured with standard materials, but the battery exhibits poor flame retardancy and safety performance
Solution Approach 1:
The patent uses a composite binder system combining polyacrylic acid (PAA) and polyvinylidene fluoride (PVDF) with ammonium polyphosphate (APP). This composite material approach creates synergistic effects where PAA provides flame retardancy through phosphorus-containing char formation, PVDF ensures mechanical adhesion, and APP enhances thermal stability and flame suppression, collectively improving battery safety without compromising manufacturability
Solution Approach 2:
The patent optimizes the mass ratio of PAA to PVDF in the binder system (specifically 1:1 to 1:3), and controls the APP content at 5-20 wt% of the total binder mass. By adjusting these compositional parameters, the battery achieves optimal balance between flame retardancy, mechanical integrity, and electrochemical performance, resolving the contradiction between safety improvement and manufacturing complexity
2Reliability
If flame retardant materials are added to improve safety, then the flame retardancy is enhanced, but the electrochemical performance and structural stability may be affected
Solution Approach 1:
The patent merges the functions of multiple materials into a unified binder system where PAA contributes flame retardancy through phosphorus oxide and polyphosphoric acid formation, PVDF provides mechanical adhesion and structural integrity, and APP enhances thermal stability. This merging of functions allows the binder to simultaneously improve safety while maintaining structural stability and electrochemical performance
Solution Approach 2:
The patent creates local quality differentiation within the binder system by positioning PAA and APP primarily at the electrode surfaces where they form protective SEI films and char layers for flame suppression, while PVDF distributes throughout the binder matrix to maintain overall mechanical adhesion. This localized functional distribution allows flame retardancy enhancement without compromising bulk structural stability
3Reliability
If ammonium polyphosphate and polyacrylic acid are compounded to improve flame retardancy, then the flame retardancy and safety are enhanced, but the binder formulation becomes more complex
Solution Approach 1:
The patent achieves multi-functionality in the binder system where the PAA-APP-PVDF composite performs multiple roles: PAA and APP provide flame retardancy through phosphorus-containing char formation and non-volatile phosphorus oxide generation, PVDF ensures mechanical adhesion, and the combination collectively provides thermal stability, electrochemical performance, and safety. This multi-functional integration reduces the need for separate additive systems, simplifying the overall formulation despite the complex chemistry involved
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 composite binder significantly improves the flame retardancy, safety, coulomb efficiency, and cycle stability of lithium ion batteries while maintaining cost-effectiveness and environmental friendliness, with improved mechanical properties and reduced risk of combustion.
Implementation Method 1
ammonium polyphosphate is heated to promote the dehydration of the surface of an organic matter to generate carbides, and the generated non-volatile phosphorus oxide and polyphosphoric acid cover the surface of a substrate
Implementation Method 2
ammonium polyphosphate is heated to promote the dehydration of the surface of an organic matter to generate carbides
Implementation Method 3
the characteristic of polyphosphoric acid to inhibit the expansion of the volume can be utilized to combine polyphosphoric acid with ammonium polyphosphate, so as to take a synergistic effect so that a stable SEI film is formed
Implementation Method 4
ammonium polyphosphate and polyacrylic acid can be crosslinked after being heated due to the interaction of hydrogen bonds so as to form a three-dimensional network structure
Implementation Method 5
ammonium polyphosphate and polyacrylic acid can be crosslinked after being heated due to the interaction of hydrogen bonds
Data Source
AI summary
The present disclosure discloses a composite binder for a self-extinguishing lithium ion battery and a lithium ion battery. The composite binder is obtained by adding ammonium polyphosphate and polyacrylic acid into a solvent to prepare a mixed solution and then carrying out thermal treatment on the above mixed solution. The present disclosure combines the flame retardancy of ammonium polyphosphate with the feature of polyacrylic acid to inhibit volume expansion, so that a stable solid electrolyte interface (SEI) film is formed on the surface of the prepared lithium ion battery during the cycling, thereby significantly promoting the electrochemical performance of the lithium ion battery while improving the flame retardancy of the battery; besides, ammonium polyphosphate and polyacrylic acid can be crosslinked after being heated due to the interaction of hydrogen bonds to form a three-dimensional network structure, which significantly improves the structural stability of the battery.