Integrated Fibrous Separator for Battery Electrode Strength

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Solution Overview

Problem

Existing electrochemical cell separators lack sufficient mechanical strength and resistance to cracking, particularly when subjected to the stresses of electrode swelling and contraction, which can lead to short circuits and reduced battery performance.

Innovation Solution

Incorporating a fibrous ceramic separator layer with ceramic particles and fibers, where the fibers are oriented laterally to enhance lateral strength and interpenetrate with active material layers, forming a non-planar interlocking region that reduces interfacial resistance and maintains mechanical integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separator layer is used in electrochemical cells, then short circuit prevention is improved, but mechanical strength and resistance to cracking are insufficient

Engineering Contradiction:

Improveshort circuit preventionVSAvoidmechanical strength and cracking resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The separator layer is formed as a composite material comprising ceramic particles dispersed within a polymer matrix. The ceramic particles (such as alumina, silica, or zirconia) provide enhanced mechanical strength, thermal stability, and crack resistance, while the polymer matrix maintains the separator's flexibility and ion conductivity. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both reliability and mechanical strength.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The separator layer exhibits non-uniform local properties through controlled variations in ceramic particle distribution, porosity, and thickness. Regions with higher ceramic particle concentration provide enhanced mechanical strength and crack resistance, while regions with optimized porosity maintain ion conductivity. This local quality variation allows the separator to simultaneously achieve both mechanical integrity and electrical function.

Inventive Principle:

Principle #3Local quality

2Strength

If the separator layer is made thicker to improve mechanical strength, then cracking resistance is improved, but ion mobility and electrode performance deteriorate

Engineering Contradiction:

Improvecracking resistanceVSAvoidion mobility and electrode performance

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The separator layer's properties are optimized by controlling key parameters including ceramic particle size distribution (typically 0.1-10 micrometers), ceramic-to-polymer ratio, porosity (30-70%), and thickness (5-50 micrometers). By adjusting these parameters, the separator achieves adequate mechanical strength and cracking resistance while maintaining sufficient ion mobility through the porous structure, thus resolving the contradiction between thickness-related strength and performance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The separator layer utilizes a porous structure with controlled pore size and distribution to balance mechanical strength and ion mobility. The porous network allows efficient ion transport pathways while the ceramic particle reinforcement within the porous matrix provides mechanical strength and cracking resistance. This porous composite approach enables the separator to achieve both properties without requiring excessive thickness.

Inventive Principle:

Principle #31Porous materials

3Strength

If a fibrous structure is added to increase lateral strength, then mechanical integrity is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvelateral strengthVSAvoidmanufacturing complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The fibrous reinforcement elements are merged with the ceramic-polymer composite matrix to form an integrated separator structure. The fibers (such as glass fibers, carbon fibers, or cellulose fibers) are incorporated during the same manufacturing process as the ceramic particle dispersion, creating a unified composite material. This merging approach enhances lateral strength while avoiding the need for separate assembly steps, thus resolving the contradiction between mechanical integrity and manufacturing complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The separator layer is formulated as a multi-component composite material comprising ceramic particles, polymer matrix, and fibrous reinforcement. This composite structure provides synergistic effects where the fibers contribute lateral strength and crack bridging, the ceramic particles provide thermal stability and puncture resistance, and the polymer matrix ensures flexibility and ion conductivity. The integrated composite approach achieves enhanced mechanical properties through a single-manufacturing process rather than multiple assembly steps.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS11594784B2Integrated fibrous separator

Publication Date: 2023.02.28 ENPOWER INC

AI summary

An electrode including an integrated fibrous separator may include an active material layer layered onto a current collector substrate, and an integrated separator layer comprising a mixture of ceramic particles and fibers layered onto the active material layer. The fibers may be oriented substantially horizontally, and may be configured to increase a lateral strength of the electrode. In some examples, the electrode includes two or more active material layers disposed between the integrated separator layer and the current collector substrate. In some examples, the electrode includes an interlocking region disposed between the active material layer and the integrated separator layer.