Lithium Ion Battery Negative Electrode Slurry with Composite Binders
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Solution Overview
Problem
Lithium ion secondary batteries face challenges in achieving excellent cycle property and low-temperature output performance, particularly in reducing size, weight, and improving performance for portable electronic devices.
Innovation Solution
A slurry composition for lithium ion secondary battery negative electrodes is developed, comprising a negative electrode active material, conductive material, water-soluble polymer, and particulate binder, with specific ranges for the conductive material and water-soluble polymer viscosity, and a combination of particulate binders A and B with varying surface acid amounts to enhance dispersibility and binding properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binders are used to produce negative electrodes, then basic battery function is achieved, but cycle property and low-temperature output property remain insufficient
Solution Approach 1:
The invention uses a composite binder system comprising both polymer binder and particulate binder in specific weight ratios (polymer binder: 5-50 wt%, particulate binder: 50-95 wt%). This composite approach combines the advantages of both binder types to achieve excellent cycle property and low-temperature output property that neither binder type can achieve alone.
Solution Approach 2:
The invention specifies precise parameter ranges for the binder components: polymer binder content (5-50 wt%), particulate binder content (50-95 wt%), and number average particle diameter (0.1-10 μm). These controlled parameter changes optimize the electrode structure to improve cycle stability and low-temperature performance.
2Reliability
If electrode materials are optimized for high performance, then battery performance improves, but battery size and weight increase
Solution Approach 1:
The invention creates a porous electrode structure through the particulate binder system with controlled particle size (0.1-10 μm number average diameter). This porous structure provides efficient ion transport pathways, maintaining high performance while reducing material density and overall battery weight.
Solution Approach 2:
The invention applies different binder components in specific proportions (polymer binder 5-50 wt%, particulate binder 50-95 wt%) to create localized functional zones within the electrode. The particulate binder provides structural framework while polymer binder ensures electrical continuity, achieving high performance with minimal material usage.
3Power
If conductive material amount is increased to reduce resistance, then low-temperature output property improves, but cycle property deteriorates
Solution Approach 1:
The invention introduces particulate binder as an intermediary component that mediates between conductive material and active material particles. The particulate binder (50-95 wt%) creates a stable structural framework that maintains electrical connectivity through low-temperature conditions while preventing excessive conductive material aggregation that would harm cycle life.
Solution Approach 2:
The composite binder system (polymer binder + particulate binder in specific ratios) creates a dual-function network: the polymer binder ensures flexible electrical connectivity for low-temperature output, while the particulate binder provides rigid structural stability for cycle longevity. This composite approach balances power and reliability.
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 results in lithium ion secondary batteries with improved cycle property and low-temperature output performance, characterized by increased binding force, reduced resistance, and enhanced dispersibility of conductive materials, leading to better battery performance and longevity.
Implementation Method 1
the water-soluble polymer has a 1% aqueous solution viscosity of 10 mPa·s to 3,000 mPa·s
Implementation Method 2
the particulate binder contains a combination of a particulate binder A with a relatively lower surface acid amount and a particulate binder B with a relatively higher surface acid amount
Data Source
AI summary
A slurry composition for a lithium ion secondary battery negative electrode including a negative electrode active material, a conductive material, a water-soluble polymer, and a particulate binder, wherein an amount of the conductive material with respect to 100 parts by weight of the negative electrode active material is 0.1 parts by weight to 10 parts by weight, the water-soluble polymer has a 1% aqueous solution viscosity of 10 mPa·s to 3,000 mPa·s, and the particulate binder contains a particulate binder A having a surface acid amount of 0.01 meq/g or more and 0.10 meq/g or less and a particulate binder B having a surface acid amount of 0.15 meq/g or more and 0.5 meq/g or less.