Secondary Battery Electrolyte and Electrode Assembly Against Metal Plating
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Solution Overview
Problem
Lithium or sodium precipitation at the negative electrode interface during the charge process of secondary batteries leads to safety risks such as battery swelling or combustion, primarily due to slow ion conduction rates and impedance imbalances.
Innovation Solution
Optimizing the structural dimension of the electrode assembly and the composition of the electrolyte in secondary batteries, including the use of a first additive with a reduction potential of 0.8 V to 1.8 V and a mass percentage of 0.1% to 15%, along with a chain ester compound and a second additive, to form a solid electrolyte interphase film, enhancing ion conduction and mitigating precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ion conduction rate is slow, then the battery can be manufactured with conventional electrolyte composition, but lithium or sodium precipitation occurs at the negative electrode interface leading to safety risks
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a first additive with specific reduction potential (0.8V to 1.8V) and a second additive, with controlled mass percentages (first additive: 0.1% to 15%, second additive: 1% to 10%). This parameter modification enables the formation of a optimized solid electrolyte interphase film that simultaneously improves ion conduction rate and prevents lithium/sodium precipitation, resolving the contradiction between safety and ion conduction speed.
2Reliability
If the electrode assembly structural dimension is not optimized, then the battery structure is simple, but deformation occurs and electrolyte infiltration is difficult leading to poor safety performance
Solution Approach 1:
The patent optimizes the structural dimension parameters of the electrode assembly by controlling the ratio n*x/y within the range of 20 to 2000, where n is the quantity of layers of the positive electrode, x is the dimension of the longest edge of the projection, and y is the maximum dimension along the thickness direction. This parameter optimization ensures the electrode assembly maintains appropriate structural dimensions that prevent deformation and facilitate electrolyte infiltration, thereby improving safety performance without excessive complexity.
3Reliability
If conventional electrolyte composition is used, then the manufacturing process is simple, but lithium or sodium precipitation occurs at the negative electrode interface during charging
Solution Approach 1:
The patent creates a composite electrolyte system by combining multiple components: a base electrolyte, a first additive with specific reduction potential (0.8V to 1.8V) at mass percentage 0.1% to 15%, and a second additive at mass percentage 1% to 10%. This composite electrolyte composition works synergistically to form a stable solid electrolyte interphase film that prevents lithium or sodium precipitation while maintaining ease of manufacture through controlled addition of specific additives to conventional electrolyte formulations.
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 optimized structure and electrolyte composition improve ion conduction rates, reducing lithium or sodium precipitation, maintaining structural stability, and enhancing safety performance by preventing adverse reactions at the negative electrode interface.
Implementation Method 1
The first additive in the electrolyte can form a solid electrolyte interphase film at a negative electrode interface that facilitates ion transport
Implementation Method 2
electrolyte infiltration is easy, maintaining structural stability of the battery during charge and discharge
Implementation Method 3
a certain amount of the chain ester compound can reduce a viscosity of the electrolyte, improving an ion conduction rate
Data Source
AI summary
An electrode assembly includes a positive electrode, a negative electrode, and a separator, and the separator is disposed between the positive electrode and the negative electrode; the electrode assembly satisfies 20≤n*x/y≤2000, where n represents a quantity of layers of the positive electrode along a thickness direction of the electrode assembly, x represents a dimension of the longest edge of a projection of the electrode assembly along the thickness direction, and y represents a maximum dimension of the electrode assembly along the thickness direction; the electrolyte includes a first additive with a reduction potential of 0.8 V to 1.8 V; and a mass percentage of the first additive in the electrolyte is denoted as a, where a is 0.1% to 15%.