All Solid Battery Inert Atmosphere Suppresses Lithium Carbonate
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Solution Overview
Problem
All solid secondary batteries using a solid electrolyte degrade over time due to the generation of resistive lithium carbonate at the cathode active material interface, which increases electrical resistance and reduces discharge capacity.
Innovation Solution
An all solid secondary battery is designed with a lithium composite transition metal oxide cathode active material, including nickel and other metals like cobalt, manganese, aluminum, or magnesium, and a sulfide-based solid electrolyte, with reduced partial pressures of carbon dioxide and oxygen to suppress lithium carbonate generation, using an inert gas substitution or evacuation to maintain low partial pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a solid electrolyte is used in the all solid secondary battery, then the energy density is improved, but lithium carbonate is generated at the cathode active material interface over time, increasing electrical resistance
Solution Approach 1:
The patent applies the inert atmosphere principle by maintaining the battery interior at reduced partial pressures of carbon dioxide and oxygen (total pressure ≤200 Pa). This creates an inert environment that prevents the chemical reaction between lithium hydroxide on the cathode surface and atmospheric gases that would otherwise form resistive lithium carbonate. The inert environment is achieved through evacuation or substitution with inert gases, directly addressing the contradiction by preserving energy density while preventing resistance increase.
Solution Approach 2:
The patent applies parameter changes by controlling the partial pressures of carbon dioxide and oxygen to be 200 Pa or less. This parameter control prevents the formation of lithium carbonate by maintaining conditions where the harmful chemical reaction cannot occur. By adjusting and maintaining this critical pressure parameter, the system achieves both high energy density and long-term reliability without electrical resistance increase.
2Productivity
If lithium nickel oxide is used as the cathode active material, then the discharge capacity is improved, but lithium carbonate generation occurs at the interface, degrading battery performance over time
Solution Approach 1:
The patent uses the inert atmosphere principle to protect the lithium nickel oxide cathode from reacting with carbon dioxide and oxygen. By maintaining the interior pressure at ≤200 Pa, the inert environment prevents lithium carbonate formation at the interface, thereby preserving both the high discharge capacity and the operational lifespan of the battery.
Solution Approach 2:
The patent applies preliminary anti-action by pre-establishing the reduced pressure environment before battery operation begins. This preventive measure counteracts the potential harmful reaction between lithium hydroxide and atmospheric gases, ensuring that the cathode interface remains clean and functional throughout the battery's service life, thus maintaining both productivity and duration.
3Reliability
If the partial pressures of carbon dioxide and oxygen are reduced to suppress lithium carbonate generation, then the electrical resistance is decreased, but additional processing steps are required to maintain the low pressure environment
Solution Approach 1:
The patent addresses the complexity issue by implementing the inert atmosphere principle through evacuation or inert gas substitution to achieve and maintain reduced partial pressures of carbon dioxide and oxygen (≤200 Pa). This approach creates a simple yet effective pressure control system that prevents lithium carbonate formation, thereby decreasing electrical resistance while avoiding overly complex active control mechanisms.
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 solution effectively decreases interfacial resistance and enhances the discharge capacity of the battery by minimizing lithium carbonate formation, improving energy density and stability.
Implementation Method 1
a solid electrolyte layer disposed between the cathode and the anode
Implementation Method 2
a cathode including a cathode active material including a transition metal oxide
Data Source
AI summary
An all solid secondary battery including: an exterior body; a cathode including a cathode active material including a transition metal oxide, an anode; and a solid electrolyte layer disposed between the cathode and the anode, wherein the cathode, the anode, and the solid electrolyte layer are disposed in the exterior body, wherein the transition metal oxide is a lithium composite transition metal oxide that contains nickel and at least one metal element other than nickel that belongs to Group 2 to Group 13 of the periodic table, and wherein the total of partial pressures of carbon dioxide and oxygen in the exterior body is 200 pascals or less.