Binder Composition for Electrical Storage Device Electrodes
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Solution Overview
Problem
Existing electrode binders for high-lithium occlusion capacity materials in electrical storage devices suffer from insufficient adhesion, durability, and long-term storage stability, leading to degradation during charge and discharge cycles.
Innovation Solution
A polymer-based binder composition with specific repeating units and an isothiazoline-based compound is used, which includes a surface acid content of 1-6 mmol/g, zeta potential of -80 to -10 mV, and a mass ratio of repeating units derived from conjugated diene, aromatic vinyl, and alpha, beta-unsaturated nitrile compounds, enhancing adhesion and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a known electrode binder is applied to a material having a high lithium occlusion capacity, then the lithium occlusion capacity is improved, but the adhesion decreases and the active material is removed due to volume changes
Solution Approach 1:
The patent changes the chemical composition parameters of the binder by incorporating specific functional groups (carboxyl, hydroxyl, amine, or isocyanate groups) that can form strong chemical bonds with high-capacity active materials like silicon and graphite. This chemical parameter modification enables the binder to maintain adhesion despite the significant volume changes (up to 300% or more) that occur during lithium occlusion and release cycles.
Solution Approach 2:
The patent creates a composite binder system combining organic polymers with specific functional groups that provide both mechanical binding and chemical adhesion. This composite approach integrates materials with complementary properties: the polymer matrix provides structural integrity while the functional groups provide strong chemical bonding to the active material particles, resulting in a durable composite that withstands volume expansion and contraction.
2Duration of action of stationary object
If the electrode binder is stored for a long time in a warehouse, then the storage stability should be maintained, but the binder may change in quality due to precipitation or degradation
Solution Approach 1:
The patent incorporates preservative agents into the binder composition before electrode manufacturing, performing preliminary protection against degradation. These preservatives are pre-selected and pre-dosed to prevent microbial growth, oxidation, and other degradation mechanisms that would occur during long-term storage, ensuring the binder maintains its properties throughout the electrode's service life.
3Quantity of substance
If a material having a high lithium occlusion capacity is used, then the energy density is improved, but the volume change during charge and discharge increases significantly
Solution Approach 1:
The patent employs the binder as a cushioning matrix that anticipates and accommodates volume changes before they cause damage. The binder's viscoelastic properties and strong adhesion create a protective cushion around active material particles, absorbing mechanical stress during expansion and contraction cycles, thereby preventing particle fracture and maintaining electrode integrity throughout the battery's operational life.
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 composition achieves excellent adhesion, charge-discharge characteristics, and long-term storage stability, particularly with high-lithium occlusion capacity materials like silicon, maintaining electrode integrity and performance over repeated cycles.
Implementation Method 1
a polymer (A) and a liquid medium (B)... the polymer (A) including a repeating unit (A4) derived from an unsaturated carboxylic acid... the polymer particles having a surface acid content of more than 1 mmol/g and 6 mmol/g or less
Implementation Method 2
JP-A-2012-9775 discloses a technique that adds a preservative in order to improve the storage stability
Data Source
AI summary
An electrical storage device electrode binder composition containing a polymer (A) and a liquid medium (B). A repeating unit (A4) derived from an unsaturated carboxylic acid compound is included in the polymer (A) in an amount of 5-40 parts by mass based on 100 parts by mass of the total repeating units in polymer (A). The polymer (A) is in particle form, and the polymer particles have a surface acid content of 1-6 mmol/g.