Nonaqueous Battery High-Voltage Gas Generation
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face challenges in maintaining safety and reliability when charged at high electric potentials above 4.3 V, particularly at higher temperatures, due to increased gas generation and structural deterioration of the positive electrode active material.
Innovation Solution
Incorporating a halogenated cyclic carbonate in the nonaqueous electrolyte liquid and forming an inorganic insulating material particle layer on the surface of the positive electrode, negative electrode, or separator to reduce gas generation and enhance impact safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the charging voltage is increased above 4.3 V to achieve higher capacity and energy density, then the battery capacity and energy density are improved, but the gas generation increases and impact safety deteriorates
Solution Approach 1:
An inorganic insulating material particle layer is introduced as an intermediary between the electrode active materials and the electrolyte. This layer mediates the interaction by providing physical separation and chemical stability, preventing direct contact between the high-potential positive electrode and the electrolyte that would otherwise cause decomposition and gas generation. The particle layer acts as a buffer that maintains safety while allowing high-voltage operation.
Solution Approach 2:
The charging voltage parameter is changed from the conventional 4.2 V or lower to above 4.3 V, operating at higher electric potentials. This parameter change enables higher capacity utilization of the positive electrode active material, but requires the protective particle layer to maintain safety. The particle layer composition and properties are specifically selected to be compatible with these elevated voltage conditions.
2Speed
If the charging temperature is increased to accelerate charging rate, then the charging speed is improved, but the gas generation increases and structural deterioration of positive electrode occurs
Solution Approach 1:
The inorganic insulating material particle layer is applied beforehand to the electrode surfaces before charging operations begin. This pre-established protective layer cushions against the harmful effects of high-temperature charging by preventing direct thermal and chemical interaction between the electrolyte and electrode materials, thereby suppressing gas generation and structural deterioration even during fast charging at elevated temperatures.
Solution Approach 2:
The inorganic insulating material particle layer serves as a sacrificial protective element that can be easily replaced or regenerated. The layer absorbs the brunt of thermal and chemical stress during high-temperature charging, protecting the more valuable electrode active materials from irreversible damage. When degradation occurs, the particle layer can be replenished without replacing the entire electrode structure.
3Object-generated harmful factors
If a halogenated cyclic carbonate is added to the nonaqueous electrolyte liquid to reduce gas generation, then the gas generation is reduced, but the electrolyte composition complexity increases
Solution Approach 1:
The electrolyte composition is modified by incorporating halogenated cyclic carbonate components, changing the chemical parameters of the electrolyte system. This compositional change alters the electrochemical stability window and reaction characteristics of the electrolyte, reducing its tendency to decompose and generate gas at high potentials. The specific ratio and type of halogenated cyclic carbonate are optimized to achieve the desired effect while managing 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
The solution effectively reduces gas generation during continuous charging at higher temperatures, maintaining high impact safety and reliability, while allowing for higher charging potentials without compromising battery performance.
Implementation Method 1
an inorganic insulating material particle layer is formed on the surface of at least either of the positive electrode, the negative electrode and the separator
Implementation Method 2
in which the positive electrode contains a positive electrode active material charged at an electric potential higher than 4.3 V based on lithium and a halogenated cyclic carbonate is added in the nonaqueous electrolyte liquid
Data Source
AI summary
A nonaqueous electrolyte secondary battery 10 according to an embodiment of the invention includes a positive electrode 11, a negative electrode 12, a separator 13 and a nonaqueous electrolyte liquid in which not only the positive electrode 11 contains a positive electrode active material charged at or higher than 4.3 V based on lithium and a halogenated cyclic carbonate is added in the nonaqueous electrolyte liquid, but also an inorganic insulating material particle layer is formed on the surface of at least either of the positive electrode 11, the negative electrode 12 and the separator 13. By employing such a constitution in the present invention, a nonaqueous electrolyte secondary battery using a positive electrode charged at a high electric potential of 4.3 V or more based on lithium in which the amount of a generated gas is small even when the battery is overcharged at higher temperatures, and the impact safety and reliability thereof are high, can be provided.