Silicon Anode Binder for Lithium Battery Cycle Life
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Solution Overview
Problem
Silicon-based and tin-based materials used as negative active materials in rechargeable lithium batteries undergo abrupt expansion and shrinkage during charge and discharge, disrupting binding and conductive networks, leading to performance issues such as reduced cycle-life characteristics.
Innovation Solution
A negative electrode is developed using a binder with a carboxyl group-containing polymer and an organic base having a cyclic structure, which provides strong peeling strength to suppress the expansion and shrinkage of the active materials, improving the cycle-life characteristics of the battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-based material or tin-based material is used as negative active material to improve discharge capacity, then energy density is improved, but the binding network is interrupted due to abrupt expansion and shrinkage during charge and discharge
Solution Approach 1:
The patent changes the chemical composition parameters of the binder by incorporating specific functional groups (carboxyl groups from polyacrylic acid and hydroxyl groups from polyvinyl alcohol) to enhance chemical bonding strength. This parameter change allows the binder to maintain binding network stability even when silicon-based or tin-based materials undergo abrupt expansion and shrinkage during charge-discharge cycles, thus resolving the contradiction between high energy density and binding network reliability
Solution Approach 2:
The patent uses a composite binder system combining polyacrylic acid and polyvinyl alcohol in specific weight ratios (0.1-10:0.1-10). This composite material approach creates a synergistic effect where the carboxyl groups and hydroxyl groups work together to form strong binding networks that can accommodate the volume changes of silicon-based or tin-based active materials, maintaining both high energy density and structural reliability
2Use of energy by moving object
If silicon-based material or tin-based material is used as negative active material to improve discharge capacity, then energy density is improved, but cycle-life characteristics deteriorate due to expansion and shrinkage
Solution Approach 1:
The patent modifies the binder's chemical parameters by introducing carboxyl and hydroxyl functional groups that form strong chemical bonds with the active material particles. This parameter change enables the binder to withstand repeated expansion and shrinkage cycles, significantly improving cycle-life characteristics while maintaining the high energy density provided by silicon-based or tin-based materials
Solution Approach 2:
The patent employs a three-dimensional network structure formed by the interaction between carboxyl groups and hydroxyl groups, creating a flexible yet robust binding matrix. This curved, interconnected network structure can accommodate the spherical or particulate morphology of silicon-based or tin-based materials during volume changes, preserving both energy density and cycle-life characteristics
3Stability of the object's composition
If conventional binder is used to maintain binding network, then structural stability is maintained, but peeling strength is insufficient to suppress expansion and shrinkage
Solution Approach 1:
The patent fundamentally changes the chemical parameters of the binder by incorporating polyacrylic acid with carboxyl groups and polyvinyl alcohol with hydroxyl groups. These functional groups form strong chemical bonds and hydrogen bonding networks, dramatically increasing peeling strength while maintaining binding network stability during the expansion and shrinkage of silicon-based or tin-based active materials
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 use of the binder with strong peeling strength enhances the adherence of the negative active material layer, leading to increased cycle-life characteristics and initial efficiency of the rechargeable lithium battery by minimizing material disruption during charging and discharging.
Implementation Method 1
a binder with a carboxyl group-containing polymer and an organic base having a cyclic structure, which provides strong peeling strength
Implementation Method 2
The use of the binder with strong peeling strength enhances the adherence of the negative active material layer
Data Source
Figure 1
AI summary
The invention relates to a negative electrode for a rechargeable lithium battery including a current collector (31) and a negative active material layer (32)positioned on the current collector. The negative active material layer includes a negative active material and a binder. The negative active material includes a silicon-based material, a tin-based material, or a combination thereof. The binder includes an organic acid including a carboxyl group-containing polymer and an organic base having a cyclic structure. A method of preparing the same, and a rechargeable lithium battery including the same are also disclosed.