Porous Negative Electrode Void Layer for Solid-State Short-Circuit Control
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Solution Overview
Problem
Solid state batteries face issues with internal short circuits due to the deposition of metallic lithium or sodium on the negative electrode, leading to increased resistance and reduced battery life, particularly in high-capacity electrodes.
Innovation Solution
A negative electrode design featuring a metal porous body with a void layer containing a solid electrolyte and voids, where the specific surface area of the metal porous body is between 500 m2/m3 and 6000 m2/m3, and the solid electrolyte density in the void layer is 1.5 g/cc to 1.8 g/cc, allowing controlled deposition of metallic lithium in the voids, thereby suppressing internal short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high-capacity negative electrode is used to increase energy density, then the battery capacity is improved, but metallic lithium deposition is more likely to occur causing internal short circuits
Solution Approach 1:
The invention creates a localized buffer region between the solid electrolyte layer and negative electrode mixture layer where metallic lithium can be deposited. This buffer layer has different properties (larger specific volume) than the surrounding structures, providing a dedicated space for lithium deposition that prevents it from causing internal short circuits between electrodes.
Solution Approach 2:
The buffer layer acts as an intermediary structure between the solid electrolyte layer and negative electrode mixture layer. It mediates the lithium deposition process by providing a controlled environment for metallic lithium formation, preventing direct contact between lithium deposits and the negative electrode that would cause short circuits.
2Reliability
If the specific volume of the buffer layer is increased to accommodate lithium deposition, then internal short circuit risk is reduced, but the basis weight of the negative electrode decreases
Solution Approach 1:
The invention optimizes the buffer layer's specific volume within a specific range (0.03 mL/g or more and 0.20 mL/g or less) to balance its dual function: providing sufficient space for lithium deposition to prevent short circuits while maintaining adequate basis weight for battery capacity. This parameter optimization resolves the contradiction between reliability and quantity.
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 design suppresses internal short circuits and maintains battery life by concentrating metallic lithium deposition in the voids, enhancing energy efficiency and reducing energy density loss.
Implementation Method 1
when metallic lithium or the like is deposited on the negative electrode, metallic lithium or the like is likely to be deposited in a concentrated manner in the pores of the metal porous body which are voids in the void layer
Implementation Method 2
in the void layer, the solid electrolyte has a density of 1.5 g/cc or more and less than 1.8 g/cc. According to this configuration, it is possible to achieve both suppression of generation of cracks in a solid state battery manufacturing process and suppression of deterioration of ion conductivity
Data Source
AI summary
A negative electrode of a solid state battery includes: a negative electrode mixture layer formed by filling pores of a metal porous body with a negative electrode mixture containing a negative electrode active material; and a void layer including a portion containing a solid electrolyte and a portion having voids in the pores of the metal porous body on a solid electrolyte layer side in a thickness direction of the metal porous body pressurized in the thickness direction, wherein a specific surface area of the metal porous body before the pressurization is 500 m2/m3 or more and 6000 m2/m3 or less.