Variable Battery Stack Pressure for Silicon Anode Swelling
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Solution Overview
Problem
Lithium-ion batteries experience significant mechanical stresses due to volume variations of silicon particles during charging and discharging cycles, leading to performance degradation and premature aging.
Innovation Solution
A system that applies variable pressure to the battery using a mechanism with multiple springs and cams controlled by an actuator, adjusting pressure based on the battery's charging and discharging phases to maintain optimal contact between silicon particles and the current collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon particles are used to increase battery capacity, then energy density is improved, but mechanical stress and particle degradation worsen due to volume expansion up to 300%
Solution Approach 1:
The battery stack is divided into multiple individual cells, each capable of independent pressure management. This segmentation allows localized adaptation to volume changes in silicon particles without affecting the entire battery structure, maintaining particle integrity while accommodating capacity increases.
Solution Approach 2:
A dynamic pressure management system is implemented that actively adjusts the pressure applied to the battery stack based on real-time monitoring of cell voltage and state of charge. The system increases pressure during discharge when silicon particles contract and reduces pressure during charging when particles expand, preventing mechanical degradation while maintaining electrical contact.
2Reliability
If pressure is applied to maintain contact between silicon particles and current collector, then electrical connectivity is improved, but particle splitting and separation worsen due to mechanical stress
Solution Approach 1:
The pressure management system operates in periodic cycles synchronized with battery charge-discharge cycles. Pressure is increased during discharge when particles contract and connectivity is at risk, then reduced during charging when particles expand. This periodic modulation maintains connectivity without applying continuous stress that would cause particle splitting.
Solution Approach 2:
The system dynamically changes the pressure parameter based on battery operating conditions, specifically adjusting pressure magnitude and timing according to state of charge and current flow. This parameter modulation ensures adequate contact pressure for electrical connectivity while avoiding excessive stress that would fragment silicon particles.
3Duration of action of stationary object
If variable pressure control is implemented to manage volume variations, then battery lifespan is improved, but device complexity increases due to additional actuators and control systems
Solution Approach 1:
The pressure management system incorporates feedback control where cell voltage and state of charge are continuously monitored to determine when pressure adjustment is needed. This feedback mechanism automates the complex pressure control decisions, extending battery lifespan through adaptive pressure management while minimizing the complexity of control logic by using straightforward voltage-threshold-based triggering.
Solution Approach 2:
The system uses the battery's own operational parameters (voltage, state of charge) to automatically control the pressure management actuator. The battery essentially manages its own mechanical stress through feedback from its electrical performance, eliminating the need for external complex control systems while extending lifespan through adaptive pressure adjustment.
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 helps maintain battery performance over time and significantly slows down aging by mitigating mechanical stresses through optimized pressure management.
Implementation Method 1
a first assembly comprising a first actuation wall extending parallel to the two end plates and located opposite the first end plate, said first assembly comprising at least one first spring inserted between the first actuation wall and the first end plate
Implementation Method 2
said first actuation wall being able to move toward or away from the first end plate to exert pressure on said first plate, under the effect of the movement of a link extending parallel to the first actuation wall and moved by an actuator, said link being connected to said first actuation wall by at least one cam
Data Source
AI summary
A system applies a variable pressure to an electric battery including at least one electrochemical cell inserted between a first end plate and a second end plate which are parallel to one another. The system includes a first assembly including a first actuating wall, at least a first spring inserted between the first actuating wall and the first end plate, a link extending parallel to the first actuating wall and moved by an actuator. The link is connected to the first actuating wall by at least one cam, a first end of which is rotatably mounted on the link, and a second end of which is rotatably mounted about an axis of rotation rigidly connected to a stationary wall. The second end bears against the first actuating wall.