Battery Cell Compression Plates for Electrode Swelling Control
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Solution Overview
Problem
Existing battery cells experience significant swelling and shrinking due to the expansion and contraction of anode and cathode materials during charge and discharge cycles, leading to increased thickness, deformation of the outer casing, and poor ion diffusion, which affects cell performance and energy density.
Innovation Solution
A battery cell design featuring an intermediate casing with compression plates on either side, exerting uniform pressure on the stack of electrochemical elements to maintain consistent contact between the anode and cathode, ensuring uniform ion diffusion and electrochemical reaction despite expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the stack of electrochemical elements is manufactured with reduced thickness to increase the margin between the stack and the external casing, then the margin is increased, but the energy density of the cell is reduced
Solution Approach 1:
The patent applies a dynamic compression system where compression plates are moved from an initial position to a compressed position during cell operation. This dynamic adjustment allows the cell to maintain optimal electrode contact despite swelling, eliminating the need for excessive initial margin volume while preserving energy density.
Solution Approach 2:
The compression force applied to the electrochemical stack is changed as a parameter in response to cell swelling. By adjusting the compression parameter during operation, the system maintains effective electrode contact without requiring a reduced-thickness design that would compromise energy density.
2Reliability
If adhesive separators are used to ensure good electrode contact, then contact quality is improved, but manufacturing cost increases and manufacturing time is extended
Solution Approach 1:
The patent replaces the chemical adhesive bonding system with a mechanical compression system. Instead of using adhesive separators that require complex manufacturing processes, the invention uses compression plates that apply mechanical force to ensure electrode contact, significantly simplifying manufacturing and improving productivity.
Solution Approach 2:
The compression plates act as intermediary elements between the external casing and the electrochemical stack. These plates transmit compression force uniformly across the electrodes, ensuring good contact without requiring adhesive materials or complex assembly processes.
3Adaptability or versatility
If the cell allows expansion during operation, then the natural swelling of electrodes is accommodated, but homogeneous pressure and uniform ion diffusion are compromised
Solution Approach 1:
The compression plates are designed to move dynamically from an initial position to a compressed position as the cell swells during operation. This dynamic adjustment maintains homogeneous pressure on the electrodes throughout the expansion process, ensuring uniform ion diffusion while accommodating the necessary cell expansion.
Solution Approach 2:
The compression plates are pre-positioned to counteract the swelling force of the electrodes as they expand. By applying preliminary compression in the opposite direction of swelling, the system maintains pressure homogeneity and prevents deformation of the external casing.
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
Maintains homogeneous pressure across the electrodes, ensuring uniform ion diffusion and electrochemical reaction, reducing deformation and maintaining cell performance and energy density.
Implementation Method 1
each compression plate exerting pressure in a first transverse direction on each main face, transmitting the pressure in the first transverse direction to the stack of electrochemical elements
Implementation Method 2
carbon graphite tends to swell when intercalated with lithium ions between the graphene layers, so the distance between the graphene layers increases as the carbon graphite swells
Data Source
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AI summary
The cell (12) of the battery (10) comprises: an outer casing (18), a stack of electrochemical elements (14), and an intermediate casing (16) having two main faces (20). Each main face (20) carries a compression plate (22) exerting pressure in a first transverse direction (T1) on each main face, transmitting the pressure in the first transverse direction (T1) to the stack of electrochemical elements (14), when the stack of electrochemical elements (14) expands, causing the deformation of the outer casing (18) during the lifetime of the cell (12).