Oxide Solid-State Battery Capacity Ratio for Longer Cycle Life
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Solution Overview
Problem
Existing solid-state batteries using oxide-based solid electrolytes face challenges in enhancing cycle characteristics without requiring additional configurations like a conductive resin layer, and carbon-based negative electrode materials cause reduction decomposition during firing.
Innovation Solution
A solid-state battery design with a specific charging capacity ratio (negative electrode capacity/positive electrode capacity) of 0.74 to 0.96, using oxide-based solid electrolytes, and a production method involving a stacked body formation and firing process to integrate positive and negative electrode layers with an oxide solid electrolyte layer in between.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric capacity ratio of the negative electrode is increased to improve cycle characteristics, then the capacity retention rate is improved, but the total surface area of the negative electrode active material increases causing reaction between moisture and Li ions on the particle surface, thereby reducing the amount of Li ions that can contribute to charge and discharge
Solution Approach 1:
The patent changes the electric capacity ratio parameter to a specific range (0.95 ≤ negative electrode capacity/positive electrode capacity < 1.20) to balance cycle characteristics improvement with preservation of Li ion contribution. This parameter optimization resolves the contradiction by finding the optimal value that prevents excessive surface area increase while still improving capacity retention.
2Device complexity
If carbon-based material is used as negative electrode active material, then the battery structure is simplified, but the material causes reduction decomposition of the oxide-based solid electrolyte during firing
Solution Approach 1:
The patent extracts the carbon-based negative electrode material from the system and replaces it with oxide-based negative electrode active material. This removal eliminates the harmful reduction decomposition reaction with the oxide-based solid electrolyte during firing, while maintaining the battery's functional structure.
Solution Approach 2:
The patent converts the potential harm of using carbon-based materials (which would reduce the oxide electrolyte) into a benefit by selecting oxide-based negative electrode materials that are chemically compatible with oxide-based solid electrolytes, ensuring stability during the firing process while maintaining structural integrity.
3Reliability
If a conductive resin layer is added to fix the electrode active material layer to the current collector layer, then the charge-discharge characteristics are improved, but the device complexity increases
Solution Approach 1:
The patent removes the conductive resin layer from the battery structure and instead uses direct contact between the oxide-based negative electrode active material particles and the oxide-based solid electrolyte to establish electrical connection. This eliminates the additional layer while maintaining charge-discharge performance through the inherent conductivity of the oxide-based materials.
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 enhances cycle characteristics by balancing the charging capacities of the positive and negative electrodes, preventing deterioration of the positive electrode active material and improving battery performance without needing a conductive resin layer.
Implementation Method 1
the obtained stacked body is fired at a predetermined temperature to fire the oxide-based solid electrolyte
Data Source
AI summary
The present application provides a solid-state battery that eliminates the need for additional components such as conductive resin layers, makes it possible to enhance cycle characteristics, and can also be applied to solid-state batteries in which oxide-based solid electrolytes are used. The present application also provides a method for producing the solid-state battery. The present invention is intended to solve the problems described above and relates to a solid-state battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer arranged between the positive electrode layer and the negative electrode layer, in which the ratio (negative electrode capacity/positive electrode capacity) of the charge storage capacity of the negative electrode layer to the charge storage capacity of the positive electrode layer is 0.74-0.96.