Electrode Coating Strategy for Stable Secondary Battery Cycling
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Solution Overview
Problem
Conventional lithium ion secondary batteries face instability due to undesired side reactions between electrode active materials and electrolytic solutions, leading to inadequate cycle characteristics, as unreacted lithium compounds can react with organic solvents, causing gas generation and material deterioration.
Innovation Solution
The battery design includes an electrode assembly where both the electrode active material and conductive auxiliary agents are coated with a covering material, such as a metal oxide or silicon-based compound, to prevent these side reactions and enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrode active material particles are mixed with conductive auxiliary agent, then electrode conductivity is improved, but particle fracture surfaces are exposed and deterioration reactions with electrolytic solution occur
Solution Approach 1:
A covering layer is formed on the electrode active material particles before mixing with the conductive auxiliary agent. This preliminary covering prevents the conductive auxiliary agent from contacting and fracturing the particle surfaces, thereby preventing exposure of fresh surfaces that would otherwise undergo deterioration reactions with the electrolytic solution.
Solution Approach 2:
The covering layer acts as an intermediary between the electrode active material particles and the conductive auxiliary agent. It allows the conductive auxiliary agent to be present in the electrode structure without directly contacting and damaging the particle surfaces, thus mediating the interaction to prevent harmful fractures while maintaining conductivity.
2Stability of the object's composition
If unreacted lithium compound reacts with organic solvent or electrolytic solution, then gas generation occurs and stability deteriorates, but complete reaction of lithium compound is difficult to achieve
Solution Approach 1:
The covering layer serves as an intermediary barrier between the unreacted lithium compound in the electrode active material and the electrolytic solution. It prevents direct contact between these substances, thereby preventing gas-generating side reactions while allowing the battery to contain unreacted lithium compound without stability issues.
Solution Approach 2:
The patent replaces the chemical reaction system with a physical barrier system. Instead of relying on complete chemical reaction of the lithium compound, a physical covering layer is used to prevent harmful reactions, substituting the need for complete reaction with a protective barrier approach.
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 approach significantly improves the cycle characteristics of the battery by suppressing gas generation and reducing cycle resistance deterioration, leading to better retention of discharge capacity and reduced electrode resistance.
Implementation Method 1
both the electrode active material and conductive auxiliary agents are coated with a covering material, such as a metal oxide or silicon-based compound, to prevent these side reactions
Data Source
AI summary
Provided is a secondary battery including an electrode including an electrode active material and another electrode-constituting material other than the electrode active material. In the secondary battery, at least a part of the electrode active material is covered with a covering material, and at least a part of the another electrode-constituting material is also covered with the covering material.