Non-aqueous electrolyte secondary battery with unsaturated additive
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face challenges in achieving high temperature lifetime and maintaining large current capacity after high temperature standing, particularly when using nonaqueous electrolytic solutions containing isocyanuric acid derivatives, which lead to increased internal resistance and impaired performance.
Innovation Solution
A nonaqueous electrolyte secondary battery design incorporating a positive electrode with a transition metal oxide composition of at least Ni and Co, along with a specific non-aqueous electrolytic solution containing a compound with a carbon-carbon unsaturated bond, such as an allyl or methallyl group, and additional components like cyclic carbonates and fluorinated species to enhance stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a nonaqueous electrolytic solution containing isocyanuric acid derivative is used, then high temperature lifetime is improved, but internal resistance increases and large current capacity deteriorates
Solution Approach 1:
The patent combines isocyanuric acid derivative (0.01-5 wt%) with specific cyclic carbonate solvents (ethylene carbonate, propylene carbonate, butylene carbonate) and chain carbonate additives to create a synergistic electrolyte system. This combination allows the isocyanuric acid derivative to provide high-temperature stability while the carbonate solvents maintain ionic conductivity and electrode interface stability, preventing excessive internal resistance increase.
Solution Approach 2:
The patent optimizes the concentration of isocyanuric acid derivative within a specific range (0.01-5 wt%) to balance its beneficial effects on high-temperature lifetime with its potential harmful effects on internal resistance. By controlling this parameter, the electrolyte achieves improved thermal stability while maintaining acceptable electrical performance.
2Object-affected harmful factors
If electrolyte composition is optimized for high temperature stability, then safety is improved, but battery characteristics (load characteristics, cycle characteristics) may deteriorate
Solution Approach 1:
The patent creates a composite electrolyte system combining isocyanuric acid derivative with multiple carbonate solvents and additives. This composite approach allows the isocyanuric acid derivative to provide overcharge protection and thermal stability, while the carbonate solvents (ethylene carbonate, propylene carbonate, butylene carbonate) maintain ion transport efficiency and electrode compatibility, ensuring good load characteristics are preserved.
Solution Approach 2:
The cyclic carbonate solvents act as intermediaries between the isocyanuric acid derivative and the electrode surfaces. They facilitate ion transport while the isocyanuric acid derivative provides protective functions, allowing safety improvements without significant loss of productivity or load characteristics.
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 improves high temperature lifetime and maintains large current capacity by reducing internal resistance and optimizing electrode reactions, leading to better battery characteristics and safety.
Implementation Method 1
a positive electrode containing a transition metal oxide capable of having occluded therein and releasing metal ions, the transition metal oxide containing at least Ni and Co... a negative electrode capable of having occluded therein and releasing metal ions... non-aqueous electrolytic solution
Data Source
AI summary
Provided is a non-aqueous electrolyte secondary battery which comprises a positive electrode containing a transition metal oxide capable of having occluded therein and releasing metal ions, the transition metal oxide containing at least Ni and Co and having the Ni and Co constituting 50 mol% or more of the transition metal; a negative electrode capable of having occluded therein and releasing metal ions; and a non-aqueous electrolytic solution comprising a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent, wherein the non-aqueous electrolytic solution contains a compound having a structure represented by the following general formula (1): wherein R1 to R3 are the same or different, and each is an organic group having 1 to 20 carbon atoms and optionally having a substituent, with the proviso that at least one of R1 to R3 has a carbon-carbon unsaturated bond; and wherein the transition metal oxide containing at least Ni and Co and having the Ni and Co constituting 50 mol% or more of the transition metal is a compound represented by the following compositional formula (4): Lia3Nib3Coc3Md3O2 ..... (4) wherein the following numbers: 0.9≤a3≤1.1, 0.35≤b3≤0.9, 0.1≤c3≤0.5 and 0.0≤d3≤0.5 satisfy the relationships: c3<b3 and 0.6≤b3+c3 and b3+c3+d3=1, and M represents at least one element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti, and Er.