Battery Positive Electrode Conductive Layer for Higher Compacted Density
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Solution Overview
Problem
Lithium-ion batteries face limitations in energy density due to the large interaction forces between nanoscale conductive carbon particles, leading to difficulties in dispersion and increased sheet resistance, which reduces compacted density and competitiveness.
Innovation Solution
An electrochemical apparatus with a conductive layer having secondary particles of 0.1 μm≤D50≤0.4 μm, incorporating additives like polyether polyol and polycarboxylic acid salts to form a network bonding structure that disperses conductive agents effectively, maintaining particle size at a small level and reducing the thickness of the conductive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If nanoscale conductive carbon particles are used in the primer layer, then adhesion between active substance layer and current collector is improved, but dispersion becomes difficult due to large interaction forces between particles
Solution Approach 1:
The patent introduces a binder as an intermediary substance between the nanoscale conductive carbon particles and the solvent. The binder has functional groups that interact with both the particles and the solvent, facilitating dispersion while maintaining particle adhesion. This mediator resolves the contradiction by enabling easy mixing without compromising the strong particle-substrate bonding.
2Strength
If particle size of slurry is reduced to nanoscale, then adhesion is improved, but coating thickness is limited and compacted density decreases
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: particle size distribution (D10, D50, D90 values), binder molecular weight, solvent composition ratio, and coating thickness. By coordinating these parameters, the patent achieves a conductive layer thickness of 3-10 μm with compacted density >1.8 g/cm³, resolving the contradiction between fine particle adhesion and overall density.
3Strength
If thickness of conductive layer is increased, then adhesion is improved, but energy density and compacted density are reduced
Solution Approach 1:
The patent identifies an optimal conductive layer thickness range of 3-10 μm, which balances adhesion requirements with energy density constraints. Within this range, the layer provides sufficient bonding strength while minimizing the non-active material volume, thereby maintaining high compacted density (>1.8 g/cm³) and energy density.
4Ease of manufacture
If molecular weight of additives is increased, then dispersion of conductive agent is improved, but viscosity increases and stirring energy consumption increases
Solution Approach 1:
The patent specifies an optimal molecular weight range for the binder (10,000-1,000,000) that balances dispersion capability with viscosity control. Within this range, the binder provides sufficient steric stabilization and particle separation while maintaining slurry流动性 for efficient mixing, thereby reducing stirring energy consumption while achieving uniform conductive agent distribution.
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 approach enhances the energy density and compacted density of the electrochemical apparatus while maintaining adhesion, thereby improving the kinetic performance and reducing internal resistance.
Implementation Method 1
both the first additive and the second additive are bonded to the conductive agent, and intermolecular forces are present between the first additive and the second additive
Implementation Method 2
Under the action of shear force, this network-like bonding structure can effectively disperse the conductive agent
Data Source
AI summary
An electrochemical apparatus includes a positive electrode. The positive electrode includes a current collector, a conductive layer, and an active substance layer, with the conductive layer disposed between the current collector and the active substance layer, where the conductive layer includes secondary particles formed from primary particles of a conductive agent, and D50 of the secondary particles satisfies 0.1 μm≤D50≤0.4 μm. The thickness of the conductive layer in the positive electrode of the electrochemical apparatus is less than 1 μm, effectively increasing the compacted density and energy density of the electrochemical apparatus.