Battery Pack Fluid Pressure Control for Cell Thickness Variation
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Solution Overview
Problem
Existing battery packs for electric and hybrid road vehicles face challenges in managing the thickness variation of electrochemical cells, requiring high initial compression forces to maintain contact between the solid electrolyte and electrodes, which leads to increased weight, volume, and complexity.
Innovation Solution
A battery pack design that incorporates adjustable pressure compartments filled with a fluid, allowing for variable pressure exertion on the cells based on operating conditions, thereby maintaining electrolyte contact without the need for cumbersome containment structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high initial compression force is applied to maintain electrolyte contact, then cell reliability is improved, but battery pack weight and volume increase
Solution Approach 1:
The patent applies dynamics by making the compression force adjustable rather than fixed. The compression device can vary the compression force applied to cells based on their state of charge and operating conditions. This allows high compression force to be applied only when necessary (e.g., during rapid recharging when thickness variation is significant) rather than continuously, reducing the overall weight and volume requirements of the compression structure while maintaining reliability.
Solution Approach 2:
The patent changes the parameter of compression force from a constant high value to a variable value that adapts to operating conditions. By monitoring cell thickness variation and state of charge, the system adjusts the compression force parameter dynamically, applying higher forces only when needed to maintain electrolyte contact during significant thickness changes, thereby optimizing the balance between reliability and weight.
2Reliability
If high initial compression force is applied to maintain electrolyte contact, then cell reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing a compression device that performs multiple functions: it provides mechanical compression to maintain electrolyte contact, serves as a structural support element, and integrates with the battery pack housing. This multi-functional approach reduces the need for separate containment structures and simplifies the overall device design while maintaining the necessary compression force for reliability.
Solution Approach 2:
The compression device is designed to automatically adjust its output based on the cell's needs without requiring complex external control systems. The system monitors cell parameters and self-regulates the compression force, reducing the need for additional sensors, actuators, and control mechanisms that would increase device complexity.
3Ease of manufacture
If fixed compression structure is used, then manufacturing simplicity is improved, but adaptability to varying operating conditions deteriorates
Solution Approach 1:
The patent implements dynamics by creating an adjustable compression device that can modify its compression force output based on operating conditions such as state of charge and temperature. This dynamic capability allows the system to adapt to varying cell thickness variations during different operating phases while maintaining a relatively simple structural design that doesn't require complex mechanical adjustment mechanisms.
4Temperature
If standard cooling fins are used, then cooling function is provided, but insufficient cooling efficiency occurs during rapid recharging
Solution Approach 1:
The patent applies dynamics by making the compression force adjustable rather than fixed. The compression device can vary the compression force applied to cells based on their state of charge and operating conditions. This allows high compression force to be applied only when necessary (e.g., during rapid recharging when thickness variation is significant) rather than continuously, reducing the overall weight and volume requirements of the compression structure while maintaining reliability.
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
This solution reduces the overall dimensions, weight, and cost of the battery pack while ensuring efficient cooling and maintaining electrolyte contact, even during rapid recharging and varying operating conditions.
Implementation Method 1
A battery pack design that incorporates adjustable pressure compartments filled with a fluid, allowing for variable pressure exertion on the cells based on operating conditions
Implementation Method 2
The battery packs of known type further comprise a plurality of cooling fins interposed between the cells and designed to cool the cells
Implementation Method 3
a first cooling fin (22) arranged between the second cell (12) and the second compartment (15b)
Data Source
AI summary
A battery pack for an electric road vehicle is described, comprising: a casing); at least a first electrochemical cell comprising, in turn, a cathode, an anode and a solid electrolyte electrically connected to the cathode and to the anode; the first cell has a thickness along a direction increasing following the activation of the first cell; the first cell is housed inside the casing; a compartment defined by the casing and designed to permit the thickness variation of the first cell; and feeding means designed to feed a fluid into the compartment with an adjustable pressure so as to exert a corresponding adjustable pressure on the first cell.