Anode Layer Expansion Control for Solid-State Battery Resistance
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Solution Overview
Problem
Anode layers in all solid-state batteries experience resistance increases due to charge and discharge cycles, primarily due to ion and electron conductive path insulation caused by volume variation of active materials, which is not effectively addressed by existing technologies.
Innovation Solution
An anode layer comprising an active material with a specific expansion coefficient range (1.4% to 5%) including a Nb element, a W element, and an O element, combined with a solid electrolyte, such as a sulfide solid electrolyte, to minimize resistance changes during charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional anode materials are used in all solid state batteries, then the battery can operate with solid electrolyte, but resistance increases significantly due to volume variation causing insulation of ion and electron conductive paths
Solution Approach 1:
The patent changes the physical parameter of expansion coefficient by selecting specific anode materials (Li4Ti5O12, TiNb2O7, Li2SiO3) with expansion coefficients of 0.05% or less when charged to 200 mAh per 1 g. This parameter control prevents excessive volume variation during charge-discharge cycles, maintaining conductive path connectivity and reducing resistance increase.
Solution Approach 2:
The patent employs composite anode materials combining multiple components (Li4Ti5O12, TiNb2O7, Li2SiO3) with complementary properties. These composite structures achieve both low expansion coefficient (0.05% or less) and high Li diffusion capability, while maintaining structural stability to prevent conductive path insulation during cycling.
2Productivity
If anode materials with high Li diffusion capability are selected, then charge-discharge performance improves, but volume variation increases causing resistance increase
Solution Approach 1:
The patent optimizes the expansion coefficient parameter to 0.05% or less while selecting materials with inherent high Li diffusion capability. This parameter control allows the anode to accommodate fast Li insertion/extraction without excessive volume change, preventing conductive path disruption and maintaining low resistance during high-rate operation.
Solution Approach 2:
The patent uses materials with locally optimized structures where Li diffusion pathways are facilitated (high Li diffusion capability) while the overall structure maintains low expansion coefficient. The local structural features enable fast ion transport without causing global volume instability that would insulate conductive paths.
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 anode layer with a controlled expansion coefficient range exhibits reduced resistance increase during charge and discharge cycles, maintaining high thermal stability and Li diffusion capability, thereby enhancing the performance of all solid-state batteries.
Implementation Method 1
an expansion coefficient of the anode active material when charged to 200 mAh per 1 g is 1.4% or more and 5% or less
Data Source
AI summary
A main object of the present disclosure is to provide an anode layer with little resistance increase due to charge and discharge. In the present disclosure, the above object is achieved by providing an anode layer comprising: an anode active material including a Nb element, a W element, and an O element; and a solid electrolyte, and an expansion coefficient of the anode active material when charged to 200 mAh per 1 g is 1.4% or more and 5% or less.