All-Solid Battery Electrode Grain Sizing for Dense Sintered Layers
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Solution Overview
Problem
Existing all solid lithium ion secondary batteries face challenges in achieving high-density electrode layers due to difficulties in improving mutual dispersibility and filling properties of electrode active materials and solid electrolytes during the sintering process.
Innovation Solution
The all solid battery design includes a solid electrolyte layer sandwiched between positive and negative electrode layers, where the average grain size of the solid electrolytes in at least one of the electrode layers is 2.5 μm or less, and the average grain size ratio of the electrode active material to the solid electrolyte is between 0.4 and 10, ensuring high-density filling and effective contact points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode active material and solid electrolyte are filled densely to achieve many contact points, then the capacity characteristics improve, but it becomes difficult to improve mutual dispersibility and filling properties
Solution Approach 1:
The invention changes the grain size parameter of the solid electrolyte to 2.5 μm or less, and controls the grain size ratio between electrode active material and solid electrolyte to be 0.4 or more and 10 or less. This parameter optimization enables both high-density filling and effective mutual dispersibility during the sintering process, resolving the contradiction between capacity characteristics and manufacturing ease.
2Volume of stationary object
If the average grain size of solid electrolyte is reduced to 2.5 μm or less, then the density and contact points increase, but the manufacturing precision requirements increase
Solution Approach 1:
The invention specifies a concrete grain size parameter (2.5 μm or less) and a grain size ratio range (0.4 or more and 10 or less), providing clear manufacturing targets that balance density improvement with achievable manufacturing precision. This quantified approach transforms the contradiction into a solvable engineering specification.
Solution Approach 2:
The invention performs preliminary grain size control of the solid electrolyte before the sintering process, ensuring that the starting material meets the 2.5 μm or less requirement. This preliminary preparation simplifies the subsequent sintering process and reduces the precision burden during final manufacturing.
3Volume of stationary object
If the area occupancy ratio of solid electrolyte is controlled to achieve high density, then the porosity decreases to 10% or less, but the electrode layer structure becomes more complex
Solution Approach 1:
The invention controls the area occupancy ratio of solid electrolyte in the electrode layer cross-section to achieve optimal density while maintaining manageable structural complexity. By combining this with the grain size control (2.5 μm or less) and grain size ratio (0.4 or more and 10 or less), the invention creates a systematic approach that achieves high density (porosity 10% or less) without excessive structural complexity.
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 allows for the achievement of a high-density electrode layer, enhancing the battery's sinterability, overall conductivity, and capacity retention rate, while maintaining a porosity of 10% or less in the electrode layers.
Implementation Method 1
a sintering process using heat treatment is required
Implementation Method 2
a sintering process using heat treatment is required
Data Source
AI summary
An all solid battery includes a solid electrolyte layer including a first solid electrolyte, a positive electrode layer provided on a first main face of the solid electrolyte layer and including a positive electrode active material and a second solid electrolyte, and a negative electrode layer provided on a second main face and including a negative electrode active material and a third solid electrolyte. In one of the positive electrode layer or the negative electrode layer, an average grain size of the second or the third solid electrolyte is 2.5 μm or less, and an average grain size ratio of an average rain size of the positive electrode active material to an average grain size of the second solid electrolyte or an average grain size ratio of the negative electrode active material to an average grain size of the third solid electrolyte is 0.4 or more and 10 or less.