Multi-layer Electrolyte Holder for Lithium Battery
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving long cycle life and preventing solution shortage and dendrite precipitation when used in industrial applications, such as vehicle mounting, due to insufficient porosity adjustment in separators and increased binding agent usage affecting capacity and cost.
Innovation Solution
A multi-layer electrolyte holder with hydrophilic fibrous layers of varying porosities is used, where the porosity at the anode interface is lower than at the cathode interface, maintaining high overall porosity to prevent dendrite growth and solution migration, ensuring efficient lithium ion migration and retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the porosity of the separator is increased to prevent solution shortage and dendrite precipitation, then battery safety and cycle life are improved, but the mechanical strength and structural stability of the separator deteriorate
Solution Approach 1:
The separator is constructed as a composite material consisting of a base separator layer and a porous coating layer. The base separator provides mechanical strength and structural stability, while the porous coating layer (with porosity of 5-50 micrometers) provides solution retention and dendrite prevention. This composite structure resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
A porous coating layer is formed on the separator surface with controlled porosity (5-50 micrometers). This porous structure increases the separator's ability to retain electrolyte solution and prevent dendrite precipitation while maintaining overall structural integrity through the underlying base separator.
2Productivity
If a multi-layer structure with varying porosities is used to optimize lithium ion migration, then battery performance is improved, but the device complexity increases
Solution Approach 1:
The separator employs local quality variation through a porous coating layer with specific porosity (5-50 micrometers) applied only on the surface facing the electrodes. This localized modification optimizes lithium ion migration at the critical interface where dendrite formation occurs, while the rest of the separator maintains its original simple structure for manufacturing ease.
Solution Approach 2:
The separator is divided into two functional segments: a base separator layer providing mechanical support and a porous coating layer providing ion migration optimization. This segmentation allows each layer to be optimized independently for its specific function while maintaining overall system simplicity.
3Object-affected harmful factors
If the porosity of the fibrous layer at the anode interface is decreased to prevent dendrite growth, then battery safety is improved, but the electrolyte retention and ion migration at the cathode interface deteriorate
Solution Approach 1:
The porous coating layer is applied specifically on the separator surface facing the electrodes, creating a localized low-porosity region (5-50 micrometers) exactly where dendrite formation occurs. This local modification prevents dendrite growth at the critical interface while leaving the rest of the separator structure unchanged to maintain electrolyte retention and ion migration efficiency.
Solution Approach 2:
The porous coating layer acts as an intermediary between the separator and the electrodes. It provides a controlled porous structure that mediates lithium ion transport, allowing ions to pass through while physically blocking dendrite formation. This intermediary layer resolves the contradiction by providing selective functionality at the electrode interface.
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 electrolyte holder effectively prolongs battery cycle life to 10,000 to 20,000 cycles and 10 to 20 years, allowing high-current charging and discharging while preventing short circuits and electrolyte shortage, making it suitable for industrial use.
Implementation Method 1
the electrolyte holder consists of a multi-layer structure having at least two hydrophilic fibrous layers having different porosities
Implementation Method 2
to repeatingly occlude and discharge lithium ions
Implementation Method 3
restraining dendrite from precipitating and growing
Data Source
AI summary
The present invention provides an electrolyte holder for a lithium secondary battery capable of holding an electrolytic solution inside electrodes or at an interface between the separator and each of the electrodes, preventing electrolyte shortage inside the electrodes, and restraining dendrite from precipitating and growing and also provide the lithium secondary battery, using the electrolyte holder, which is capable of achieving a cycle life to such an extent that the lithium secondary battery can be used for industrial application. An electrolyte holder (3) for use in the lithium secondary battery consists of a multi-layer structure having at least two hydrophilic fibrous layers (A, B) having different porosities. The electrolyte holder (3) is composed of an electrode group formed by winding a cathode (2) and an anode (1) or laminating the cathode (2) and the anode (1) one upon another with an electrolyte holder (3) serving as a separator interposed between the cathode (2) and the anode (1). The organic electrolytic solution is permeated into the electrode group or the electrode group is immersed in the organic electrolytic solution. A porosity (40% to 80%) of the fibrous layer (A) disposed at an interface between the fibrous layer (A) and the anode (1) is set smaller than a porosity (60% to 90%) of the fibrous layer (B) disposed at an interface between the fibrous layer (B) and the cathode (2). An average porosity of the entire fibrous layer is set to not less than 50%. The fibrous layers are formed by using cellulose fibers as a main material thereof. An active substance for use in the anode (1) is a carbon material.