Secondary Battery Cap Assembly for Axial Expansion Buffering
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Solution Overview
Problem
Secondary batteries face performance and life issues due to excessive expansion forces from electrode assemblies, which can lead to fracturing and failure, as existing technologies do not effectively manage these forces within the battery module.
Innovation Solution
A secondary battery design featuring a cap assembly with an insulating member and buffer gaps to absorb and distribute expansion forces along the axial direction, preventing excessive force accumulation and ensuring even deformation of electrode units, thereby enhancing safety and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If electrode assemblies are arranged sequentially in battery modules, then battery capacity and energy density are improved, but expansion forces accumulate in the arrangement direction causing excessive composite force that presses secondary batteries
Solution Approach 1:
The electrode assembly is segmented into multiple electrode units stacked in the axial direction. This segmentation allows expansion forces to be distributed across multiple stacking directions rather than accumulating in a single arrangement direction, reducing the composite force pressing on secondary batteries while maintaining battery capacity through increased electrode unit quantity.
Solution Approach 2:
The patent transitions from a single-plane electrode arrangement to a three-dimensional stacked structure with electrode units arranged both in the axial direction (stacking) and radial direction (arrangement). This dimensional change disperses expansion forces across multiple spatial dimensions, preventing force accumulation in any single direction while preserving high battery capacity.
2Power
If electrode assemblies expand during charge/discharge processes, then electrochemical reactions are enhanced, but expanding forces accumulate and form excessive composite force pressing secondary batteries
Solution Approach 1:
Buffer gaps are designed between adjacent electrode units in the axial direction before assembly. These pre-designed buffer gaps provide cushioning space that absorbs expansion forces during charge/discharge processes, preventing excessive force accumulation that would compromise battery reliability while allowing unrestricted electrochemical reactions.
Solution Approach 2:
The buffer gaps act as intermediary spaces between electrode units, mediating the expansion forces generated during electrochemical reactions. These gaps absorb and distribute the mechanical stress, allowing the electrochemical reactions to proceed at high rates without transmitting excessive forces to the battery structure.
3Force
If buffer gaps are provided between adjacent electrode units, then expansion forces are absorbed and distributed, but manufacturing precision requirements increase
Solution Approach 1:
The buffer gaps are designed with dimensions that are intentionally larger than the minimum required for force absorption. This excessive action approach provides a tolerance margin that reduces manufacturing precision requirements, allowing buffer gaps to effectively absorb expansion forces even with normal dimensional variations during assembly.
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 manages expansion forces along the axial direction, preventing fracturing and ensuring the longevity and safety of secondary batteries by evenly distributing the expansive deformation, thus improving the overall performance and life of the battery module.
Implementation Method 1
the insulating member is positioned at a side of the electrode assembly in the axial direction... effectively manages expansion forces along the axial direction... evenly distributing the expansive deformation
Implementation Method 2
buffer gaps to absorb and distribute expansion forces along the axial direction, preventing excessive force accumulation and ensuring even deformation of electrode units
Data Source
Figure 1
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AI summary
The present disclosure provides a secondary battery and a battery module. The secondary battery includes an electrode assembly, a case and a cap assembly. The case includes an accommodating cavity, and the electrode assembly is accommodated in the accommodating cavity. The electrode assembly includes electrode units, which are stacked in an axial direction of the accommodating cavity. The cap assembly includes a cap plate and an insulating member disposed on an inner side of the cap plate. The cap plate is connected to the case, and the insulating member is located on a side of the electrode assembly in the axial direction. The insulating member is provided with a first surface at a side close to the electrode assembly, and the first surface is a flat surface. A battery module includes second batteries, which are arranged sequentially and an arrangement direction of which is perpendicular to the axial direction.