Hard Carbon Anode Binder with Controlled Latex Size for Flexibility
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Solution Overview
Problem
Existing anode plates with hard carbon materials face challenges in achieving a balance between binding capability, cohesion, and flexibility, leading to issues such as carbon deintercalation and brittleness, which affects the stability and energy density of secondary batteries.
Innovation Solution
A styrene-acrylic emulsion with latex particles of 350-900 nm is used as a binder for the anode active material layer, providing improved binding and cohesion forces while maintaining flexibility, by using a styrene acrylate copolymer with a specific particle size range and glass transition temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional binders are used in anode plates with hard carbon materials, then the binding capability can be achieved, but the cohesion and flexibility deteriorate, leading to carbon deintercalation and brittleness
Solution Approach 1:
The patent changes the particle size parameter of the binder from conventional larger sizes to specifically 350-900 nm range, and controls the glass transition temperature of the styrene acrylate copolymer to be in a specific range. These parameter changes enable the binder to simultaneously achieve strong binding capability and maintain flexibility, resolving the contradiction between binding strength and flexibility.
Solution Approach 2:
The patent uses a composite binder system consisting of styrene acrylate copolymer with specific composition ratios (styrene 30-80%, acrylate 20-70%). This composite material combines the advantages of different monomers to achieve both strong adhesion to hard carbon particles and sufficient flexibility, preventing carbon deintercalation while maintaining ease of operation.
2Strength
If the binder amount is increased to improve binding force, then the binding capability improves, but the flexibility and energy density deteriorate
Solution Approach 1:
The patent optimizes the particle size parameter of the binder to 350-900 nm, which provides a large specific surface area that enhances binding force per unit mass. This parameter change allows achieving strong binding force with minimal binder quantity, thereby maintaining high energy density while improving binding capability.
3Quantity of substance
If high coating weight is applied to increase capacity, then the energy capabilities improve, but the flexibility and cycle stability deteriorate
Solution Approach 1:
The patent controls the particle size of the styrene acrylate copolymer binder within 350-900 nm and its glass transition temperature within a specific range. These parameter changes enable the binder to maintain strong adhesion and flexibility even at high coating weights, ensuring both high energy capabilities and good cycle stability by preventing carbon deintercalation during 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 solution enhances the binding force and cohesion of the anode plate, ensuring better cycle stability and energy capabilities without compromising the flexibility, even at high coating weights, thus improving the overall performance of secondary batteries.
Implementation Method 1
the binder is derived from the styrene-acrylic emulsion... providing improved binding and cohesion forces
Implementation Method 2
the binder is derived from the styrene-acrylic emulsion... providing improved binding and cohesion forces
Implementation Method 3
adding an initiator to carry out a polymerization reaction to produce a styrene-acrylic emulsion having a latex particle with a Dv50 particle size of 350-900 nm
Data Source
AI summary
The present application relates to a styrene-acrylic emulsion and a preparation method therefor, an anode plate, a secondary battery and an electric device. A Dv50 particle size of a latex particle in the styrene-acrylic emulsion is 350-900 nm, optionally 350-800 nm. The anode plate includes an anode current collector; and an anode active material layer disposed on at least one surface of the anode current collector, the anode active material layer includes a hard carbon material and a binder, the binder is derived from the above-mentioned styrene-acrylic emulsion.