Lithium Battery Wrinkle Prevention via Electrolyte Volume Control
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Solution Overview
Problem
Lithium secondary batteries with built-in film-covered batteries, featuring a lithium complex oxide sintered plate as a positive electrode, tend to develop wrinkles near the positive electrode tab terminal when subjected to repeated bending tests, as the excess electrolyte solution creates space that leads to wrinkles.
Innovation Solution
A lithium secondary battery design with a lithium complex oxide sintered plate, a carbon-containing negative electrode layer, a separator, and an optimized electrolyte solution volume, where the separator's outer peripheral portion is in close contact with the exterior film, and the electrolyte solution's volume is between 1.05 to 1.25 times the total void volume of the battery components, reducing excess space and internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a lithium complex oxide sintered plate is used as a positive electrode, then capacity and charge/discharge efficiency are improved, but wrinkles occur on the card surface during repeated bending tests
Solution Approach 1:
The patent optimizes the distance parameter Wp between the sealed part and the positive electrode plate within a specific range (1.0 to 3.0 mm) to prevent wrinkle formation while maintaining the benefits of the sintered plate structure for high capacity and charge/discharge efficiency
Solution Approach 2:
The patent pre-establishes a buffer space by controlling the distance Wp between the sealed part and the positive electrode plate, which cushions against the formation of wrinkles during repeated bending tests before they occur
2Ease of manufacture
If powder-dispersed positive electrodes are used, then manufacturing is easier, but packing density of active material is low resulting in reduced capacity
Solution Approach 1:
The patent uses a lithium complex oxide sintered plate as a composite material that combines high packing density of active material with the structural integrity needed for flexible card applications, overcoming the limitations of powder-dispersed electrodes
Data Source
AI summary
Provided is a lithium secondary battery including: a positive electrode plate being a lithium complex oxide sintered plate; a negative electrode layer; a separator; a positive electrode current collector foil; a negative electrode current collector foil; an electrolytic solution; a pair of exterior films having outer peripheral edges sealed with each other to form an internal space that accommodates the battery elements; a positive electrode tab terminal; and a negative electrode tab terminal, wherein the inner peripheral edge of the sealed part of the exterior films and the outer peripheral edge of the positive electrode plate are apart from each other at a distance Wp of 2.0 to 4.0 mm on the side on which the positive electrode tab terminal is sealed, and the electrolytic solution has a volume of 1.05 to 1.25 times the total void volume of the positive electrode plate, the separator, and the negative electrode layer.