Laminated Battery Cell Separator Edges for Lithium Debris Confinement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laminated battery cells, particularly those with lithium metal negative electrodes, are prone to short circuits during charging and discharging due to the generation of 'dead lithium' and 'powdered lithium', which can cause safety hazards such as fire or explosion.
Innovation Solution
A laminated battery cell design that includes an adhesive film layer on the separator's side edges to confine 'dead lithium' and 'powdered lithium' within an accommodating region, using a specific width and thickness relationship to prevent overflow and direct contact with the positive electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a laminated battery cell uses a conventional separator without adhesive film layer, then the manufacturing process is simple and device complexity is low, but dead lithium and powdered lithium can escape from the negative electrode sheet causing short circuits and safety hazards
Solution Approach 1:
The separator is divided into two functional layers: a separator body for basic isolation and an adhesive film layer for confining lithium debris. This segmentation allows each layer to specialize in one function, improving safety without significantly complicating the overall structure.
Solution Approach 2:
The adhesive film layer acts as an intermediary between the negative electrode sheet and the separator body. It mediates the confinement of lithium debris, preventing direct contact between dead lithium and the positive electrode while maintaining the basic separator function.
2Reliability
If the adhesive film layer is made wide to effectively confine negative electrode sheet and lithium debris, then safety is improved, but the adhesive film layer may overflow onto the main body of the negative electrode sheet after hot pressing
Solution Approach 1:
The width of the adhesive film layer is optimized to a specific range (greater than 1/3 but less than 1/2 of the width difference between separator body and negative electrode sheet). This parameter optimization ensures effective confinement while preventing overflow during hot pressing, balancing safety and manufacturing precision.
3Reliability
If the adhesive film layer is made thick to improve adhesion and confinement, then reliability is improved, but it may produce protrusions causing stress concentration in the battery cell
Solution Approach 1:
The thickness of the adhesive film layer is controlled to be not greater than the thickness of the negative electrode sheet. This parameter control ensures sufficient adhesion for confinement while avoiding protrusions that would cause stress concentration and potential failure points in the battery cell structure.
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 design effectively reduces the probability of short circuits, enhancing safety by immobilizing lithium debris and preventing direct contact with the positive electrode, thereby reducing the risk of fires or explosions.
Implementation Method 1
an adhesive film layer is disposed on at least part of the side edge
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
The present application belongs to the technical field of batteries, and particularly relates to an laminated battery cell, a secondary battery and an electrical apparatus. The laminated battery cell provided by the present application comprises a positive electrode sheet, a negative electrode sheet and a separator, the separator comprising a separator body; the separator body comprises a side surface facing the negative electrode sheet, the side surface being provided with a side edge, and at least part of the side edge being provided with an adhesive film layer; the adhesive film layer is arranged in a first direction and/or a second direction of the plane where the separator body is located, so as to form an accommodation area, the negative electrode sheet being located in the accommodation area. The laminated battery cell helps to improve the safety of batteries.