Sodium-Ion Battery Electrolyte With Cyclic Sulfate for Low Resistance
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Solution Overview
Problem
Existing sodium ion secondary batteries face high negative electrode resistance and excessive gas generation during durability tests, which are not adequately addressed by existing additives.
Innovation Solution
A non-aqueous electrolyte solution for sodium ion secondary batteries containing a cyclic sulfate and NaPF6 at specific ratios, along with a non-aqueous solvent, is used to reduce negative electrode resistance and limit gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a non-graphitic carbon material is used as a negative electrode material to achieve high capacity, then the battery capacity is improved, but the negative electrode resistance increases
Solution Approach 1:
A cyclic sulfate compound is introduced as an intermediary substance in the electrolyte solution. This compound mediates between the non-graphitic carbon negative electrode and the sodium ions, facilitating smoother ion transport and reducing interfacial resistance while maintaining high capacity utilization
Solution Approach 2:
The electrolyte solution composition is modified by adding a cyclic sulfate compound at a specific concentration ratio (0.001 to 1.5 molar ratio relative to NaPF6). This parameter change in the electrolyte composition alters the interfacial properties between the electrolyte and negative electrode, reducing resistance without compromising capacity
2Reliability
If conventional electrolyte additives are used to improve battery performance, then capacity retention is improved, but gas generation during durability tests increases
Solution Approach 1:
The cyclic sulfate compound undergoes controlled reductive decomposition during initial charging cycles, converting the potential harmful gas-generating side reactions into a beneficial process. This decomposition forms a stable coating film on the negative electrode that prevents further unwanted reactions and minimizes gas generation during subsequent durability testing
Solution Approach 2:
The cyclic sulfate compound performs preliminary protective action by forming a stable interface coating film during initial charging cycles. This preliminary film formation prevents subsequent harmful reactions between the electrolyte and electrode materials, thereby reducing gas generation during long-term durability tests while maintaining capacity retention
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 results in a sodium ion secondary battery with low resistance and minimal volume change after durability testing, enhancing battery performance and stability.
Implementation Method 1
the stability of a negative electrode coating film formed by reductive decomposition of a solvent during initial charging varies between a sodium ion secondary battery and a lithium ion secondary battery
Implementation Method 2
sodium ion secondary batteries using sodium ions as a charge carrier
Data Source
AI summary
The present invention is aimed at providing: a non-aqueous electrolyte solution for a sodium ion secondary battery, with which a sodium ion secondary battery having a low resistance and showing a limited amount of gas generation after a durability test can be provided; and a sodium ion secondary battery obtained by using the same. The non-aqueous electrolyte solution for a sodium ion secondary battery comprises: a non-aqueous solvent; NaPF6; and a compound represented by the following Formula (1) (wherein, R1 and R2 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and n represents 0 or 1), and a ratio of the content of the compound represented by Formula (1) with respect to the content of NaPF6, [compound represented by Formula (1)]/[NaPF6] (molar ratio), is 0.001 to 1.5: