Separator Porous Layer Retains Electrolyte
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Solution Overview
Problem
Conventional lithium ion batteries experience degradation in durability and performance during high-rate charge and discharge cycles due to a shortage of electrolytic solution between the positive and negative electrodes, leading to increased battery resistance.
Innovation Solution
A nonaqueous electrolyte secondary battery with a porous layer formed on the separator sheet, featuring an inorganic filler and binder, with an uneven surface to retain electrolytic solution, preventing solution shortage and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional lithium ion batteries are used for high-rate charge and discharge applications, then the battery can provide high power output, but the battery resistance increases significantly and durability decreases due to electrolytic solution shortage between electrodes
Solution Approach 1:
A porous layer is formed on the separator sheet to retain electrolytic solution. The porous structure provides large surface area and capillary action to hold electrolyte, preventing solution shortage between electrodes during high-rate charge and discharge cycles, thus improving durability while maintaining power output
Solution Approach 2:
The porous layer is pre-formed on the separator sheet before battery assembly to preliminarily retain electrolytic solution. This preliminary action ensures electrolyte is already positioned and retained in the separator before high-rate operation begins, preventing electrolyte depletion and maintaining reliable performance
2Productivity
If high-rate charge and discharge are repeated, then the battery can meet vehicular power source requirements, but the amount of electrolytic solution between positive and negative electrodes decreases due to solution being pushed out
Solution Approach 1:
The porous layer acts as an electrolyte reservoir that compensates for solution loss during high-rate operation. The porous structure's capillary forces retain electrolyte against the outward push during rapid charge-discharge cycles, maintaining sufficient electrolyte quantity between electrodes
Solution Approach 2:
The porous layer serves as an intermediary between the bulk electrolyte and the electrode surfaces. It mediates the electrolyte distribution, preventing direct electrolyte depletion at the electrode interfaces during high-rate charge and discharge by providing a buffered reservoir
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 porous layer effectively retains electrolytic solution, mitigating solution shortages and significantly increasing the battery's durability against high-rate charge and discharge cycles, maintaining performance and reducing resistance.
Implementation Method 1
a porous layer including an inorganic filler and a binder is formed on at least one surface of the separator sheet. A surface of the porous layer is made uneven by forming peaks and valleys, and a maximum difference of elevation on an uneven surface is 0.2 μm to 1.7 μm
Data Source
AI summary
A nonaqueous electrolyte secondary battery provided by the present invention includes an electrode body in which a positive electrode sheet and a negative electrode sheet 20 are laminated with a separator sheet 40 interposed therebetween. A porous layer 42 including an inorganic filler and a binder is formed on at least one surface of the separator sheet 40. The surface of the porous layer 42 is made uneven by forming peaks and valleys, and a maximum difference of elevation on an uneven surface 42a is 0.2 μm to 1.7 μm.