Non-aqueous Electrolyte Battery Stabilizing Positive Electrode
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Solution Overview
Problem
Conventional non-aqueous electrolyte secondary batteries fail to provide excellent high-temperature storage characteristics and safety against overcharge due to high-rate charging, despite attempts to improve the stability of the positive electrode using additives like Zr or Mg.
Innovation Solution
A non-aqueous electrolyte secondary battery design incorporating a positive electrode with a layered lithium-transition metal composite oxide containing Mg, Al, or Ti, and a non-aqueous electrolyte with 3 to 80% tertiary carboxylic acid ester, such as methyl trimethylacetate, which enhances the stability and reduces reactions between the electrolyte and the electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a lithium-cobalt composite oxide is used as a positive electrode active material, then high energy density and high capacity are achieved, but the non-aqueous solvent reacts with the positive electrode and is decomposed to generate gas, reducing battery safety
Solution Approach 1:
The patent modifies the chemical composition parameters of the lithium-cobalt composite oxide by adding specific elements (Mg, Al, Ti, Zr) to change the material's properties. This compositional parameter change reduces the reactivity between the positive electrode and non-aqueous solvent, preventing gas generation while maintaining high energy density
Solution Approach 2:
The patent creates a composite positive electrode active material by combining lithium-cobalt composite oxide with other elements (Mg, Al, Ti, or Zr). This composite structure provides both high energy density from the lithium-cobalt base and improved safety from the additional elements that stabilize the material and reduce solvent decomposition
2Stability of the object's composition
If elements such as Zr or Mg are added to the lithium-cobalt composite oxide to improve structure stability, then structure stability is enhanced, but the problem of solvent decomposition and gas generation is not sufficiently solved
Solution Approach 1:
The patent optimizes the compositional parameters by specifying precise addition ranges of Mg, Al, Ti, or Zr (0.01-5 mol% each) to the lithium-cobalt composite oxide. This parameter optimization ensures sufficient structure stability while achieving adequate suppression of solvent decomposition and gas generation that was not accomplished by conventional additions
Solution Approach 2:
The patent develops an optimized composite material system where lithium-cobalt composite oxide is combined with specific amounts of stabilizing elements (Mg, Al, Ti, or Zr). This composite approach provides synergistic effects that simultaneously enhance structure stability and prevent solvent decomposition more effectively than conventional single-element additions
3Ease of operation
If conventional non-aqueous electrolyte compositions are used, then basic battery function is maintained, but excellent high-temperature storage characteristics and safety against overcharge due to high-rate charging are not achieved
Solution Approach 1:
The patent modifies the electrolyte composition parameters by incorporating specific additives (cyclic carboxylate compound and/or chain carboxylate compound) within defined concentration ranges. These parameter changes enable the electrolyte to provide excellent high-temperature storage characteristics and overcharge safety while maintaining basic battery function
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 significantly improves high-temperature storage characteristics and safety against overcharge by synergistically stabilizing the positive electrode and reducing electrolyte reactions, resulting in higher capacity retention rates and limiting currents.
Implementation Method 1
a positive electrode active material containing a layered lithium-transition metal composite oxide containing at least one element selected from the group consisting of Mg, Al, Ti, and Zr
Implementation Method 2
the non-aqueous electrolyte contains 3 to 80% by mass of a tertiary carboxylic acid ester... reduces the reaction between the non-aqueous electrolyte and the positive electrode active material
Data Source
AI summary
A non-aqueous electrolyte secondary battery includes a positive electrode containing a positive electrode active material; a negative electrode containing a negative electrode active material; and a non-aqueous electrolyte containing a non-aqueous solvent and an electrolyte salt. In order to improve the high-temperature storage characteristics and safety against overcharge due to high-rate charging of the battery, the positive electrode active material contains a layered lithium-transition metal composite oxide containing at least one of Mg, Al, Ti, and Zr. Furthermore, the non-aqueous electrolyte contains 3 to 80% by mass of a tertiary carboxylic acid ester expressed by Chemical Formula 2 below, based on the total mass of the non-aqueous solvent:where R1 to R4 are independent of each other and each represents an alkyl group having 4 or less carbon atoms and being able to be branched.