Lithium-Metal Separator Structure for Dendrite Suppression
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Solution Overview
Problem
Nonaqueous electrolyte energy storage devices using lithium metal as a negative active material face the challenge of lithium dendrite formation, which can lead to short circuits due to dendrite penetration through the separator and contact with the positive electrode.
Innovation Solution
The device incorporates a negative electrode with a lithium metal active material layer, a positive electrode with a fluorine-containing nonaqueous electrolyte, and a separator with an inorganic particle layer, ensuring the surface of the negative active material layer and inorganic particle layer face each other, and the separator has specific air permeability, preventing dendrite formation and short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as a negative active material to increase discharge capacity, then the discharge capacity per active material mass is significantly increased, but lithium dendrites form during charge which can penetrate the separator and cause short circuits
Solution Approach 1:
An inorganic particle layer is introduced as an intermediary between the lithium metal negative active material and the separator. This layer acts as a physical barrier that prevents lithium dendrites from penetrating through the separator to the positive electrode, while still allowing lithium ion transport. The inorganic particles provide a protective interface that maintains both high capacity and safety.
Solution Approach 2:
The separator is modified by adding an inorganic particle layer specifically at the region facing the negative electrode, where lithium dendrite formation occurs. This localized modification provides targeted protection against dendrite penetration without affecting other regions of the separator, optimizing both performance and safety.
2Productivity
If the separator air permeability is increased to improve lithium ion transport, then the charge-discharge performance is enhanced, but the mechanical strength and dendrite blocking capability are reduced
Solution Approach 1:
The separator is constructed as a composite structure combining an organic base material with an inorganic particle layer. The organic component provides mechanical strength and flexibility, while the inorganic particle layer provides enhanced thermal stability, chemical inertness, and dendrite blocking capability. This composite structure achieves both high productivity and strength.
Solution Approach 2:
The inorganic particle layer is designed with a porous structure that allows efficient lithium ion transport while maintaining mechanical integrity. The porous configuration enables high air permeability for good charge-discharge performance, while the interconnected pore structure and particle framework provide sufficient mechanical strength and dendrite blocking 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 configuration effectively suppresses dendrite growth and short circuit occurrence, maintaining uniform current distribution and enhancing oxidation resistance, thereby improving the safety and performance of the energy storage device.
Implementation Method 1
a separator having a substrate layer and an inorganic particle layer layered on a surface of the substrate layer
Implementation Method 2
a nonaqueous electrolyte interposed between the electrodes, and is configured to allow charge transport ions to be transferred between both the electrodes
Implementation Method 3
the separator has an air permeability of 110 [sec/100 cm3] or more and 450 [sec/100 cm3] or less
Data Source
AI summary
A nonaqueous electrolyte energy storage device according to one aspect of the present invention includes: a negative electrode having a negative active material layer containing lithium metal; a positive electrode having a positive active material layer; a nonaqueous electrolyte containing a liquid containing a fluorine atom; and a separator having a substrate layer and an inorganic particle layer layered on a surface of the substrate layer, wherein the surface of the negative active material layer and the surface of the inorganic particle layer are stacked so as to face each other, and the separator has an air permeability of 110 [sec/100 cm3] or more and 450 [sec/100 cm3] or less.