Li-Ion Battery Ultrasonic Charging to Suppress Lithium Dendrites
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Solution Overview
Problem
Lithium dendrites formed on the anode of lithium-ion batteries during charging can lead to short circuits, fires, and explosions, and existing solutions like pressure sensors and magnetic fields are inadequate or inefficient in preventing this.
Innovation Solution
Generating longitudinal ultrasonic waves in the electrolyte with a variable frequency, transverse to the migration path of lithium ions, to disrupt their deposition on the anode and break existing dendrites, using piezo-electric ultrasonic transducers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If metallic lithium anodes are used to enable powerful accumulators, then energy density is improved, but the risk of dendrite formation and short circuits increases
Solution Approach 1:
The patent applies ultrasonic vibration to the anode surface during charging to mechanically disrupt dendrite formation. The vibration causes lithium ions to deposit more uniformly across the anode surface rather than concentrating at protrusions, thereby preventing dendrite growth while maintaining high energy density with metallic lithium anodes.
Solution Approach 2:
The patent employs periodic ultrasonic treatment during the charging process. By applying vibrations at specific intervals and frequencies, the system periodically disrupts the lithium ion deposition process, preventing the continuous growth of dendrites while allowing efficient charging and maintaining high energy density.
2Difficulty of detecting and measuring
If pressure sensors are installed to detect anode shape changes, then dendrite detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical pressure sensor system with an ultrasonic vibration-based prevention system. Instead of using multiple sensors to detect dendrite formation after it occurs, the ultrasonic vibration actively prevents dendrite formation at the source, eliminating the need for complex sensor arrays while maintaining safety.
Solution Approach 2:
The ultrasonic vibration system enables the anode to self-regulate its surface morphology during charging. The vibration causes lithium ions to redistribute uniformly across the anode surface, allowing the system to maintain its own safety without requiring external monitoring devices, thereby reducing device complexity.
3Reliability
If magnetic fields are applied to shield anode protrusions, then dendrite formation at protrusions is reduced, but smallest projections remain vulnerable and effectiveness is limited
Solution Approach 1:
The patent uses ultrasonic mechanical vibration instead of magnetic fields to prevent dendrite formation. The vibration physically agitates the electrolyte and lithium ions near the anode surface, ensuring that even the smallest projections cannot concentrate enough ions to initiate dendrite growth, thereby overcoming the limitation of magnetic field shielding.
Solution Approach 2:
The patent replaces the magnetic field approach with a mechanical vibration approach. The ultrasonic vibrations create physical disturbances in the electrolyte and at the anode surface that are more effective at preventing dendrite initiation on small projections compared to magnetic field effects, thereby improving reliability.
4Reliability
If complete discharge is performed periodically to reform dendrites, then surface roughness is reduced, but this solution is not suitable for automotive applications
Solution Approach 1:
The patent applies ultrasonic vibration during the charging process to prevent dendrite formation in the first place, rather than waiting for complete discharge to reform dendrites afterward. This preliminary prevention approach allows continuous operation without requiring full discharge cycles, making it suitable for automotive applications where continuous power delivery is needed.
Solution Approach 2:
The ultrasonic vibration treatment operates continuously during charging, maintaining constant prevention of dendrite formation. This continuous action eliminates the need for periodic complete discharge cycles to reform dendrites, enabling continuous operation that is essential for automotive applications while maintaining high 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
Effectively prevents and reduces the formation and growth of lithium dendrites, minimizing the risk of short circuits by disrupting lithium ion migration and breaking existing dendrites, even in complex battery systems.
Implementation Method 1
during a charging process longitudinal ultrasonic waves, of which the longitudinal direction in the electrolyte is running transverse to the normals to the anode and to the cathode, are generated in the cell or transmitted into the cell
Implementation Method 2
using piezo-electric ultrasonic transducers
Data Source
AI summary
A method for influencing the growth of lithium dendrites in a lithium-ion rechargeable battery having in a cell (1) a cathode (4) and opposite the latter an anode (3) consisting of lithium or having at least one surface containing lithium, an anhydrous electrolyte (5) being situated in an interspace between the cathode (4) and the anode (3) and a separator (6) permeable to lithium ions being arranged in said interspace. During an electrical charging process, longitudinal ultrasonic waves having a variable frequency are generated in the cell (1) or transmitted into the cell (1), the longitudinal direction of the ultrasonic waves in the electrolyte (5) extending transversely to the normals (16) to the anode (3) and the cathode (4), and the frequency of the ultrasonic waves being controlled such that it repeatedly passes through a frequency range.