Composite negative electrode sheet, preparation method thereof, lithium ion battery using same
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Solution Overview
Problem
Conventional lithium ion battery separators made of resin materials like polyethylene or polypropylene are prone to shrinkage or melting at high temperatures, leading to direct contact between the positive and negative electrode sheets, causing thermal runaway, combustion, and explosion.
Innovation Solution
A composite negative electrode sheet is developed with a current collector, an active coating, and an insulation coating composed of a polymer, inorganic filler, and fast ion conductor, where the solubility parameter difference between the polymer and binder is greater than 0.5, enhancing structural stability and preventing direct contact between electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional resin separator materials (polyethylene or polypropylene) are used, then the battery structure is simple and manufacturing is easy, but the separator is prone to shrinkage or melting at high temperatures causing thermal runaway
Solution Approach 1:
The patent applies composite materials by combining polymer binder with inorganic fillers (such as aluminum oxide, aluminum hydroxide, magnesium hydroxide) and fast ion conductors to create an insulation coating that maintains thermal stability while preserving manufacturing simplicity. The composite structure allows the separator to resist high-temperature shrinkage and melting, preventing thermal runaway without complicating the manufacturing process.
Solution Approach 2:
The patent changes the physical and chemical parameters of the separator by incorporating inorganic fillers and fast ion conductors into the polymer matrix. This modifies the thermal properties, shrinkage resistance, and ionic conductivity of the separator material, enabling it to maintain structural integrity at elevated temperatures while still allowing ion transport.
2Stability of the object's composition
If the solubility parameter difference between polymer and binder is greater than 0.5, then the insulation coating has improved structural stability and impact resistance, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a solubility parameter difference |Δδ| > 0.5 between the polymer and binder as a critical parameter threshold. This parameter control ensures proper phase separation and interfacial adhesion in the insulation coating, achieving enhanced structural stability and impact resistance while maintaining manufacturability through defined compositional ranges.
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 composite negative electrode sheet improves impact resistance, mechanical strength, and cycle stability, reducing the risk of short circuits and thermal runaway, while maintaining high ionic conductivity and thermal stability.
Implementation Method 1
the insulation coating includes a polymer, an inorganic filler, and a fast ion conductor
Implementation Method 2
the insulation coating includes a polymer, an inorganic filler, and a fast ion conductor
Data Source
AI summary
A composite negative electrode sheet, a preparation method thereof, and a lithium ion battery using the same are provided. The composite negative electrode sheet includes a current collector, an active coating and an insulation coating that are disposed in sequence. The insulation coating includes a polymer, an inorganic filler, and a fast ion conductor, the active coating includes a binder and an active material, and a solubility parameter difference between the polymer and the binder is expressed as |Δϵ| that is greater than 0.5 (J/cm3)1/2.