Silicon Oxide Anode Binder Composition for Cycle-Stable Power Density
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Solution Overview
Problem
Current battery cell anode electrodes face challenges in achieving high power density and cycle stability due to the expansion and contraction of silicon particles during lithiation and de-lithiation, which leads to mechanical stress and reduced capacity retention.
Innovation Solution
The anode electrode incorporates a binder mixture of styrene butadiene rubber (SBR) with sodium carboxymethyl cellulose (NaCMC) and sodium polyacrylic acid (NaPAA), along with conductive fillers like carbon black and carbon nanotubes, to enhance mechanical and electrochemical properties, optimizing the anode active material layer composition with lithium silicon oxide and graphite.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon particles are used in the anode active material layer to increase capacity, then the energy density is improved, but the expansion and contraction during lithiation and de-lithiation causes mechanical stress and reduces cycle stability
Solution Approach 1:
The patent changes the chemical composition parameters of the binder system by incorporating sodium polyacrylic acid (NaPAA) with specific weight percentages (0.1-5% of anode active material layer) alongside SBR and NaCMC. This parameter modification enables the binder to accommodate silicon's volume changes during cycling while maintaining electrode integrity, thus resolving the contradiction between high energy density and cycle stability
Solution Approach 2:
The patent employs a composite binder system combining three different materials (SBR, NaCMC, and NaPAA) with complementary properties. SBR provides mechanical flexibility, NaCMC offers adhesion, and NaPAA contributes to structural stability during expansion/contraction. This composite approach allows the electrode to maintain both high silicon content for energy density and sufficient mechanical integrity for cycle stability
2Strength
If the binder composition is optimized to improve adhesion and cohesion, then the mechanical strength is improved, but the ionic resistance may increase
Solution Approach 1:
The patent optimizes the weight percentage parameters of each binder component to achieve the desired balance. Specifically, SBR is limited to 1-5% wt, NaCMC to 0.1-3% wt, and NaPAA to 0.1-5% wt of the anode active material layer. These controlled parameter changes ensure sufficient adhesion and cohesion while minimizing ionic resistance through optimized binder thickness and composition
3Power
If the anode active material layer composition is optimized for high power density, then the energy capacity is improved, but the mechanical stress from silicon expansion and contraction increases
Solution Approach 1:
The patent modifies the compositional parameters of the anode active material layer to include 70-95% wt silicon-based materials (silicon oxide, lithium silicon oxide, or silicon) while incorporating graphite (5-30% wt) and optimizing binder content. This parameter optimization enables high power density through increased silicon content while the accompanying graphite and optimized binder system mitigate mechanical stress through their structural stability and flexibility
Solution Approach 2:
The patent creates a composite anode active material layer combining silicon-based materials with graphite and optimized binder systems. The graphite provides structural stability during cycling, while the tri-component binder (SBR, NaCMC, NaPAA) provides mechanical flexibility and stress distribution. This composite structure enables high power density while managing the mechanical stress from silicon expansion and contraction
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
This configuration improves capacity retention, peel strength, and reduces ionic resistance, enabling higher power density and longer cycle life while maintaining sufficient adhesion and cohesion for roll-to-roll production.
Implementation Method 1
maintaining sufficient adhesion and cohesion for roll-to-roll production
Implementation Method 2
maintaining sufficient adhesion and cohesion for roll-to-roll production
Implementation Method 3
conductive fillers like carbon black and carbon nanotubes, to enhance mechanical and electrochemical properties
Implementation Method 4
the expansion and contraction of silicon particles during lithiation and de-lithiation
Data Source
AI summary
An anode electrode comprises an anode current collector. An anode active material layer comprises anode active material comprising at least one of lithium silicon oxide, silicon oxide, lithium silicon oxide and graphite, and silicon oxide and graphite. The anode active material layer further comprises a binder comprising a mixture of styrene butadiene rubber (SBR), sodium carboxymethyl cellulose (NaCMC) and sodium polyacrylic acid (NaPAA), wherein SBR comprises greater than 60% wt of the binder.