Solid-State Battery Anode Composition for Low Interface Resistance
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Solution Overview
Problem
Conventional solid-state batteries face challenges in reducing interface resistance between the negative electrode active material and the solid electrolyte, leading to decreased lithium ion mobility and lower volume energy density due to the difficulty in forming a dense interface.
Innovation Solution
Incorporating a negative electrode layer composed of a Li composite oxide and an oxide glass-based solid electrolyte, with a content percentage of the solid electrolyte ranging from 20% to 60% by mass and a density ratio of the negative electrode active material to its true density between 0.3 to 0.6, to enhance the interface contact and ion conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a garnet-type oxide-based solid electrolyte is used in the negative electrode layer, then the battery structure is simplified, but the interface resistance between the active material and solid electrolyte increases due to difficulty in forming a dense interface
Solution Approach 1:
The patent changes the physical and chemical parameters of the negative electrode layer by controlling the density ratio (actual density/true density) to be 0.25 to 0.65 and the solid electrolyte content to be 20-60 wt%. These parameter adjustments optimize the interface contact between active material particles and solid electrolyte, reducing interface resistance while maintaining structural simplicity.
Solution Approach 2:
The patent creates a composite negative electrode layer comprising Li composite oxide particles and oxide glass-based solid electrolyte in specific proportions. This composite structure ensures adequate contact between different materials, achieving both structural simplicity and low interface resistance through the synergistic combination of active material and solid electrolyte.
2Reliability
If the solid electrolyte content in the negative electrode layer is increased to reduce interface resistance, then lithium ion mobility improves, but the volume energy density decreases due to increased porosity
Solution Approach 1:
The patent optimizes the solid electrolyte content parameter to be within 20-60 wt% of the total negative electrode layer mass. This parameter range is carefully selected to balance two opposing requirements: sufficient solid electrolyte for low interface resistance and good lithium ion mobility, while limiting excessive solid electrolyte that would increase porosity and reduce volume energy density.
Solution Approach 2:
The patent applies local quality by ensuring the solid electrolyte is distributed throughout the negative electrode layer in optimal amounts, creating locally dense interfaces between active material particles and solid electrolyte. This localized optimization reduces interface resistance without requiring overall high solid electrolyte content that would increase porosity.
3Quantity of substance
If the density ratio of the negative electrode active material is increased to improve volume energy density, then the volume energy density improves, but the interface contact between active material and solid electrolyte deteriorates
Solution Approach 1:
The patent establishes an optimal range for the density ratio (actual density/true density) of the negative electrode active material to be 0.25 to 0.65. This parameter optimization ensures that the active material maintains sufficient porosity for good solid electrolyte penetration and interface contact, while still achieving high volume energy density through efficient space utilization.
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 reduces interface resistance, improves lithium ion mobility, and enhances the volume energy density of the solid-state battery, achieving charge-discharge efficiencies of 85% or more.
Implementation Method 1
a solid electrolyte interposed between the electrode layers of the positive electrode layer and negative electrode layer
Data Source
AI summary
A solid-state battery including: a negative electrode layer including: a negative electrode active material including a Li composite oxide; and an oxide glass-based solid electrolyte, in which a content percentage of the solid electrolyte is 20% by mass to 60% by mass based on a total amount of the negative electrode active material and the solid electrolyte in the negative electrode layer, and a ratio (B/A) of an actual density B of the negative electrode active material to a true density A of the negative electrode active material is 0.3 to 0.6.