Porous Separator Layer Balancing Electrode Adhesion and Ion Flow
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Solution Overview
Problem
Lithium-ion batteries face a reduction in cycle capacity and service life due to gaps forming between the electrode and the separator during the charging and discharging process.
Innovation Solution
A separator with a porous layer comprising inorganic particles and a binder is used, where the ratio of Dv90 of the inorganic particles to the thickness of the porous layer is between 0.3 and 3.0, maintaining excellent adhesive force and improving the rate and cycle performance of the energy storage device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a conventional separator is used, then the structure is simple, but gaps form between the separator and electrode during charging and discharging, reducing cycle capacity and service life
Solution Approach 1:
The patent applies porous inorganic particles (such as alumina, silica, or boehmite) with specific pore structures to the separator surface. These porous materials maintain open channels that accommodate electrode expansion and contraction during cycling, preventing gap formation while preserving ionic conductivity. The pore size and distribution are controlled to balance mechanical flexibility with ion transport efficiency.
Solution Approach 2:
The separator is constructed as a composite material combining organic binder polymers (like polyvinylidene fluoride or carboxymethyl cellulose) with inorganic porous particles. This composite structure provides both the mechanical integrity needed to prevent gaps and the porous network required for ion transport and electrode accommodation during charge-discharge cycles.
2Strength
If the porous layer thickness is increased to maintain adhesive force, then adhesion improves, but ionic conductivity may be reduced due to potential pore blockage
Solution Approach 1:
The separator design implements local quality by creating a porous layer with specific thickness (0.2-10 μm) and controlled pore distribution. The porous structure provides enhanced adhesion to the electrode while the carefully controlled pore size and connectivity ensure that ionic pathways remain open. Different regions of the separator have optimized properties: the porous layer near the electrode provides adhesion, while the bulk maintains porosity for ion transport.
Solution Approach 2:
The patent optimizes critical parameters including the thickness of the porous layer (0.2-10 μm), the size distribution of inorganic particles (Dv90/thickness ratio of 0.3-3.0), and the porosity (20-90%). By precisely controlling these parameters, the separator achieves both strong adhesion and maintained ionic conductivity, resolving the trade-off between these two properties.
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 proposed separator effectively reduces the probability of pore blockage, enhances ionic conductivity, and improves the rate and cycle performance of lithium-ion batteries, thereby extending their service life.
Implementation Method 1
excellent adhesive force between the separator and the electrode can be maintained
Implementation Method 2
the rate performance and cycle performance of the energy storage device can be improved due to the pore structures maintained in the separator
Data Source
AI summary
An energy storage device includes a separator, the separator includes a porous substrate, and a porous layer arranged on a surface of the porous substrate. The porous layer comprises inorganic particles and a binder, and a ratio of Dv90 of the inorganic particles to the thickness of the porous layer is in a range from 0.3 to 3.0. Excellent adhesion exists between the separator and the electrode according to the present application, which ensures that the energy storage device has good safety performance. Moreover, the rate performance and cycle performance of the energy storage device can be greatly improved due to the existence of inorganic particles in the separator.