Secondary Battery With Solid Electrolyte Separator
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges in high temperature durability and low temperature output performance, particularly when used in vehicles, due to the limitations of nonaqueous electrolytes, which have low ion conductivity and poor thermal stability, and aqueous electrolytes, which suffer from hydrogen generation and low discharge capacity.
Innovation Solution
A secondary battery design incorporating a positive electrode, a negative electrode, a separator with lithium ion conductive solid electrolyte, and distinct electrolytes in each electrode, where the second electrolyte has a higher pH and increased lithium ion concentration to reduce hydrogen generation and improve ion conductivity, and the use of titanium-containing oxides to enhance lithium ion insertion and extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nonaqueous electrolytic solution is used, then ion conductivity is improved, but thermal stability deteriorates
Solution Approach 1:
The patent changes the concentration parameter of lithium ions in the electrolyte by using different lithium salt concentrations in different electrodes. The second electrolyte has a higher lithium ion concentration (4-12 mol/L) compared to conventional electrolytes, which improves ion conductivity while the specific composition maintains thermal stability.
Solution Approach 2:
The patent uses a composite electrolyte system where different electrolytes with specific compositions are used in different electrodes. The second electrolyte contains a lithium salt and water in a specific ratio, creating a composite material that achieves both high ion conductivity and thermal stability.
2Stability of the object's composition
If aqueous electrolytic solution is used, then thermal stability is improved, but hydrogen generation increases
Solution Approach 1:
The patent changes the pH parameter and lithium ion concentration parameter of the aqueous electrolyte. The second electrolyte has a higher pH and higher lithium ion concentration (4-12 mol/L), which suppresses hydrogen generation at the negative electrode while maintaining thermal stability of the aqueous system.
Solution Approach 2:
The patent introduces a solid electrolyte as an intermediary layer between the two electrodes. This solid electrolyte allows lithium ion conduction while preventing direct contact between the aqueous electrolyte and the negative electrode, thereby suppressing hydrogen generation.
3Reliability
If lithium ion concentration is increased, then ion conductivity is improved, but resistance increases
Solution Approach 1:
The patent optimizes the lithium ion concentration parameter in the second electrolyte to be in the range of 4-12 mol/L. This specific concentration range achieves high ion conductivity while managing resistance through the coordinated effect of high lithium ion concentration and high pH conditions.
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 enhances the battery's discharge capacity, cycle life, and high current performance by reducing resistance and hydrogen generation, making it suitable for both high and low temperature environments.
Implementation Method 1
The separator includes a lithium ion conductive solid electrolyte
Implementation Method 2
the use of titanium-containing oxides to enhance lithium ion insertion and extraction
Implementation Method 3
the second electrolyte has a higher pH and increased lithium ion concentration to reduce hydrogen generation
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
According to one approach, a secondary battery including a positive electrode (3), a negative electrode (4), a separator (5), a first electrolyte, and a second electrolyte is provided. The separator (5) is provided at least between the positive electrode (3) and the negative electrode (4). The separator (5) includes an alkali metal ion conductive solid electrolyte. The first electrolyte is contained in at least the positive electrode (3). The first electrolyte includes a first alkali metal salt and a first aqueous solvent. The second electrolyte is contained in at least the negative electrode (4). The second electrolyte includes a second alkali metal salt and a second aqueous solvent.