Negative Electrode Segmentation for Solid-State Battery Safety
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Solution Overview
Problem
Solid-state batteries using alloying active materials face a trade-off between energy density and safety due to the expansion of negative electrode active materials, which can penetrate through the solid electrolyte layer, leading to loss of function, and increasing the thickness of the electrolyte layer reduces energy density.
Innovation Solution
A battery design with a negative electrode active material layer comprising a first active material that forms an alloy with Li and a second active material layer acting as a buffer, which does not contain materials that form alloys with Li, enhancing safety and energy density by preventing penetration during expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the solid electrolyte layer is increased to prevent penetration of alloying active material, then safety is improved, but energy density deteriorates
Solution Approach 1:
The negative electrode active material layer is segmented into two distinct layers: a first active material layer containing alloying active material and a second active material layer containing non-alloying active material. This segmentation allows the alloying material to be isolated from the electrolyte interface, preventing penetration while maintaining high energy density without requiring a thicker electrolyte layer.
Solution Approach 2:
The second active material layer acts as an intermediary buffer layer between the alloying active material and the solid electrolyte. This intermediary layer prevents direct contact and potential penetration of the alloying material into the electrolyte, while still allowing lithium ion transport, thus maintaining safety without compromising energy density.
2Quantity of substance
If alloying active material is used to increase energy density, then energy density is improved, but safety deteriorates due to expansion and penetration
Solution Approach 1:
The negative electrode is divided into two functional layers: the first layer utilizes alloying active material (such as silicon or tin) to achieve high energy density, while the second layer uses non-alloying active material to provide structural stability and prevent penetration. This segmentation enables simultaneous achievement of high energy density and safety.
Solution Approach 2:
The negative electrode employs a composite structure combining alloying active material and non-alloying active material in distinct layers. This composite design leverages the high capacity of alloying materials while the non-alloying layer provides mechanical stability and prevents electrolyte penetration, achieving both high energy density and safety.
3Quantity of substance
If the negative electrode active material layer is made thicker to increase capacity, then energy density is improved, but the risk of penetration through electrolyte increases
Solution Approach 1:
The thick negative electrode active material layer is segmented into two sub-layers with different functions. The first sub-layer can be thicker to provide high capacity, while the second sub-layer acts as a protective buffer near the electrolyte interface. This segmentation allows increased overall capacity while maintaining safety by isolating the expansion-prone material from the electrolyte.
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 battery achieves both high energy density and safety by preventing the first active material from penetrating through the electrolyte layer while maintaining sufficient discharge capacity and lithium ion conductivity.
Implementation Method 1
a solid electrolyte layer located between the positive electrode and the negative electrode
Implementation Method 2
the first active material layer contains, as a first active material, a material that forms an alloy with Li
Data Source
AI summary
A battery of the present disclosure includes a positive electrode, a negative electrode, and an electrolyte layer located between the positive electrode and the negative electrode. The negative electrode includes a negative electrode current collector and a negative electrode active material layer located between the negative electrode current collector and the electrolyte layer. The negative electrode active material layer includes a first active material layer and a second active material layer located between the first active material layer and the electrolyte layer. The first active material layer contains, as a first active material, a material that forms an alloy with Li. The second active material layer contains a second active material and a solid electrolyte, and does not contain a material that forms an alloy with Li.