Secondary Battery Anode Layer Structure Against Lithium Dendrites
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Solution Overview
Problem
Lithium-ion secondary batteries face issues with lithium dendrite growth, leading to separator puncture, short circuits, and safety hazards, while conventional solutions to prevent lithium evolution reduce energy density.
Innovation Solution
A secondary battery design with a negative electrode plate featuring a negative electrode current collector, an insulation layer, and a reaction layer, where the capacity of the positive electrode active material layer is larger than that of the negative electrode, and the insulation and reaction layers are composed of materials like graphite and aluminum oxide to physically and chemically inhibit lithium dendrite growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating is provided on a separator to prevent puncturing by lithium dendrites, then safety is improved, but the coating may be broken under tension and becomes ineffective
Solution Approach 1:
The patent introduces a buffer layer between the separator and the coating layer. This buffer layer acts as an intermediary that absorbs the tension stress, preventing the coating from breaking under mechanical stress while maintaining its protective function against lithium dendrites
Solution Approach 2:
The patent creates a composite structure consisting of the separator, buffer layer, and coating layer. This multi-layer composite design combines the mechanical strength of the separator with the protective properties of the coating, while the buffer layer provides stress relief
2Reliability
If the capacity of the positive electrode is made smaller than that of the negative electrode to prevent lithium evolution, then safety is improved, but the energy density is reduced
Solution Approach 1:
The patent converts the harmful lithium dendrites into beneficial lithium storage material by providing a reaction layer that reacts with the dendrites to form lithium storage compounds. This transforms the safety hazard into a useful function for maintaining capacity balance
Solution Approach 2:
The patent extracts the lithium evolution problem from the electrode capacity design by introducing a separate reaction layer that handles lithium dendrite management, allowing the electrodes to be optimized for energy density without capacity ratio constraints
3Reliability
If a coating is provided on the separator to prevent lithium dendrite puncture, then safety is improved, but the lithium storage amount of the coating material is low
Solution Approach 1:
The patent creates a composite reaction layer combining materials with high lithium storage capacity such as silicon oxide, tin oxide, or zinc oxide. These composite materials provide both the protective barrier function and sufficient lithium storage capability
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 design enhances energy density and safety by preventing lithium dendrite-induced short circuits and improving cycle performance without increasing battery volume, ensuring effective absorption of lithium dendrites and reducing the risk of battery failure.
Implementation Method 1
an insulation layer and a reaction layer are sequentially provided on the surface of the negative electrode active material layer
Implementation Method 2
the reaction layer comprises at least one of graphite, silicon, silicon oxide, silicon suboxide, tin oxide, copper oxide, and zinc oxide
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3~5
AI summary
Provided in the present application is a secondary battery comprising a positive electrode plate and a negative electrode plate, wherein the negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, an insulation layer and a reaction layer are sequentially provided on the surface of the negative electrode active material layer on the side opposite to the negative electrode current collector side, and the reaction layer comprises at least one of graphite, silicon, silicon oxide, silicon suboxide, tin oxide, copper oxide, and zinc oxide, and when the capacity of the positive electrode active material layer per unit area in the positive electrode plate is denoted as A1, and the capacity of the negative electrode active material layer per unit area in the negative electrode plate is denoted as B1, B1/A1 < 1. In the secondary battery provided by the present application, by making B1/A1 < 1, the energy density is improved, and by providing a special layer structure, it has better cycle performance.