Dynamic Battery Pressure Control via Piezoelectric Actuation
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Solution Overview
Problem
Lithium ion batteries experience mechanical stresses due to volume changes during charging and discharging, leading to increased internal resistance and potential damage, which existing methods fail to adequately address.
Innovation Solution
A method and device that adjust pressure on the battery as a function of its volume and state of charge, reducing pressure when the battery volume increases and increasing it when volume decreases, using adjustable pressure generating means such as piezoelectric elements to maintain optimal cell alignment and reduce mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If constant contact pressure is applied to prevent layer separation, then mechanical stability is improved, but internal electrical resistance increases due to overcompression of separator and deformation of electrode materials
Solution Approach 1:
The patent applies a dynamic pressure adjustment mechanism that varies the contact pressure based on the battery's state of charge. When the battery is charged (expanded state), lower pressure is applied to prevent overcompression of the separator and deformation of electrode materials. When discharged (contracted state), higher pressure is applied to maintain layer contact and prevent separation. This dynamic adaptation resolves the contradiction between maintaining mechanical stability and avoiding increased internal resistance.
2Strength
If constant pressure is applied to maintain layer contact, then mechanical stress resistance is improved, but cycle life is reduced due to cumulative mechanical stress during volume changes
Solution Approach 1:
The dynamic pressure adjustment mechanism adapts the contact pressure to the battery's current volume state, applying higher pressure only when the battery is discharged and contracted, and reducing pressure when charged and expanded. This prevents cumulative mechanical stress that would occur with constant pressure application, thereby extending cycle life while maintaining adequate mechanical stress resistance when needed.
Solution Approach 2:
The patent changes the pressure parameter dynamically based on the state of charge and volume of the battery. By adjusting the pressure level according to these parameters, the system optimizes the balance between maintaining layer contact and minimizing mechanical stress accumulation, thus improving cycle life without sacrificing mechanical stability.
3Strength
If rigid housing is used to maintain structural integrity, then mechanical strength is improved, but pressure-induced stress builds up during battery expansion and contraction
Solution Approach 1:
The patent introduces a dynamic pressure adjustment mechanism that compensates for the rigid housing's inability to accommodate volume changes. By reducing the applied contact pressure when the battery is charged and expanded, and increasing it when discharged and contracted, the system prevents pressure-induced stress buildup while maintaining structural integrity through active control rather than passive rigid constraints.
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 approach significantly increases the cycle life of lithium ion batteries by minimizing mechanical stress and maintaining low internal resistance, while allowing for real-time monitoring and adjustment of pressure conditions.
Implementation Method 1
at least one piezoelectric pressure generating means (15) which acts on the battery (10) and by changing the voltage applied across said piezoelectric pressure generating means (15), pressure can be generated on the battery (10)
Data Source
AI summary
A method and device is disclosed for application of a pressure to a battery which has at least one or more cells, in order to reduce adverse effects on operation which occur because of different battery states of charge. The device is designed to carry out the method such that the pressure is adjusted as a function of the respective battery volume and/or of the respective battery state of charge.