Lithium-Ion Battery Electrolyte for Suppressing Negative Electrode Plating
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Solution Overview
Problem
Lithium-ion batteries face safety issues due to lithium plating on the negative electrode plate, particularly in regions with uneven current densities and low CB values, leading to potential hazards.
Innovation Solution
An electrolyte containing metal ions such as K+, Rb+, and Cs+ with controlled molar concentrations (0.03 M to 0.25 M) is introduced to form electrostatic shielding and steric hindrance, homogenizing current densities and suppressing lithium plating, while maintaining electrochemical inertness within the operating voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte without metal ions is used, then the battery structure is simple and manufacturing is easy, but lithium plating occurs on the negative electrode plate leading to safety issues
Solution Approach 1:
Metal ions (K+, Rb+, Cs+) are introduced as intermediary substances in the electrolyte to mediate the interaction between lithium ions and the negative electrode plate. These metal ions migrate to low CB value regions and form electrostatic shielding, preventing direct lithium plating while maintaining electrolyte functionality. This intermediary mechanism resolves the contradiction by adding a functional component that actively prevents harmful lithium plating.
Solution Approach 2:
The electrolyte composition is modified by changing the concentration parameters of metal ions (0.03 M ≤ C M ≤ 0.25 M) and lithium ions (0.8 M ≤ C Li ≤ 1.2 M). By adjusting these concentration parameters, the electrolyte achieves optimal performance in preventing lithium plating while maintaining electrochemical stability and battery functionality.
2Reliability
If metal ions are added to the electrolyte to form electrostatic shielding, then lithium plating is suppressed, but the electrolyte composition becomes more complex
Solution Approach 1:
The concentration of metal ions is precisely controlled within the range of 0.03 M to 0.25 M to achieve effective lithium plating suppression. This parameter optimization ensures that sufficient metal ions are present to form electrostatic shielding in low CB value regions, while excessive metal ions that would increase complexity are avoided.
Solution Approach 2:
The electrolyte is formulated as a composite system containing multiple types of ions (metal ions K+/Rb+/Cs+ and lithium ions) with specific concentration ratios. This composite electrolyte composition synergistically combines the electrostatic shielding effect of metal ions with the charge transport function of lithium ions, achieving lithium plating suppression while maintaining overall system functionality.
3Reliability
If the concentration of metal ions is increased to improve shielding effect, then lithium plating suppression is enhanced, but capacity retention rate decreases
Solution Approach 1:
The metal ion concentration is optimized within the specific range of 0.03 M to 0.25 M to balance two competing requirements: providing sufficient metal ions for effective electrostatic shielding (requiring higher concentration) and maintaining good capacity retention rate (requiring lower concentration to minimize interference with lithium ion transport). This parameter optimization resolves the contradiction by identifying the optimal concentration window.
Solution Approach 2:
Instead of using a very high concentration of metal ions that would guarantee complete shielding but harm capacity retention, the invention uses a moderate concentration (0.03-0.25 M) that provides sufficient shielding effect in critical low CB value regions while allowing adequate lithium ion transport. This partial action approach achieves the necessary protection without excessive interference.
4Reliability
If CB value is increased to 1.03-1.2 to provide more lithium-ion active sites, then lithium plating risk is reduced, but the battery design becomes more constrained
Solution Approach 1:
The CB value parameter is optimized to the range of 1.03 to 1.2, which provides sufficient lithium-ion active sites to accommodate lithium ions that cannot intercalate due to electrostatic shielding. This parameter adjustment ensures that even with the shielding effect of metal ions, there are enough available sites to prevent lithium plating, thereby resolving the contradiction between plating prevention and design flexibility.
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
The electrolyte effectively mitigates lithium plating, enhancing the safety and capacity retention of lithium-ion batteries by stabilizing metal ions and adjusting the CB value to 1.03 to 1.2, ensuring more lithium-ion active sites and reducing the risk of plating.
Implementation Method 1
an appropriate amount of free metal ions in the electrolyte can move to positions on a negative electrode plate with uneven current densities, where lithium plating easily occurs, forming electrostatic shielding or steric hindrance, thereby mitigating/alleviating lithium plating on the negative electrode plate
Implementation Method 2
an appropriate amount of free metal ions in the electrolyte can move to positions on a negative electrode plate with uneven current densities, where lithium plating easily occurs, forming electrostatic shielding or steric hindrance
Implementation Method 3
potassium ions having a Stokes radius smaller than that of lithium ions are selected as the metal ions, and potassium ions move faster than lithium ions to the positions on the negative electrode plate with uneven current densities, where lithium plating easily occurs, effectively homogenizing the current densities on the negative electrode plate
Data Source
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AI summary
Disclosed in embodiments of the present application are an electrolyte, a lithium-ion battery, and an electric device. The electrolyte comprises a metal ion including at least one of K+, Rb+, and Cs+; and the molar concentration CM of the metal ion in the electrolyte satisfies: 0.03M ≤ CM. When applied in lithium-ion batteries, the electrolyte can effectively reduce the risk of lithium plating on the negative electrode and improve the safety performance of the lithium-ion batteries.