Secondary Battery Electrode Coating via Linear Carbonate Electrolyte
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Solution Overview
Problem
Conventional secondary batteries do not effectively improve battery characteristics due to the SEI coating on the negative electrode surface, which causes resistance and limited degradation of cyclic carbonates during charging, leading to suboptimal battery performance.
Innovation Solution
A method for producing a secondary battery using an electrolytic solution with a specific metal salt and linear carbonate, involving a charging and discharging process that forms a coating containing S, O, and C on the electrode surfaces, enhancing battery characteristics by improving the degradation of the electrolyte and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a SEI coating is formed on the negative electrode surface using conventional electrolytic solutions containing cyclic carbonates, then the electrolytic solution degradation is inhibited and battery life is extended, but the battery characteristics are not improved and resistance increases
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolytic solution by replacing cyclic carbonate with specific linear carbonate compounds (ethyl methyl carbonate, ethyl propyl carbonate, or propyl propyl carbonate) and using lithium bis(fluorosulfonyl)imide as the electrolyte. This parameter change transforms the SEI coating properties to reduce resistance while maintaining protective functions.
Solution Approach 2:
The patent creates a composite electrolytic solution system combining specific linear carbonate esters with lithium bis(fluorosulfonyl)imide electrolyte. This composite approach generates a novel SEI coating with both protective and conductive properties, resolving the contradiction between battery life extension and resistance reduction.
2Reliability
If charging is performed at a slow rate of 0.1 to 0.3C to form a satisfactory SEI coating, then the SEI coating is sufficiently formed, but the productivity and charging speed are reduced
Solution Approach 1:
The patent changes the electrolyte composition parameters to enable rapid SEI coating formation. The specific linear carbonate esters combined with lithium bis(fluorosulfonyl)imide allow the SEI coating to form adequately even at high charging rates of 1C or higher, thus resolving the contradiction between coating quality and charging speed.
3Quantity of substance
If cyclic carbonate is used to dissolve the electrolyte and form SEI coating, then the electrolyte is suitably dissolved and SEI coating is formed, but the coating causes resistance and does not improve battery characteristics
Solution Approach 1:
The patent extracts and removes the cyclic carbonate component from the electrolytic solution, replacing it with linear carbonate esters. This extraction eliminates the source of high-resistance SEI coating while maintaining the essential functions of electrolyte dissolution and SEI formation through the alternative linear carbonate compounds.
Solution Approach 2:
The patent changes the chemical structure parameter of the carbonate from cyclic to linear form, specifically using ethyl methyl carbonate, ethyl propyl carbonate, or propyl propyl carbonate. This structural parameter change fundamentally alters the SEI coating properties to reduce resistance while preserving electrolyte dissolution capability.
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 method results in a secondary battery with excellent battery characteristics, including reduced resistance during charging and discharging, and improved durability due to the formation of a coating that facilitates faster lithium ion passage and enhances the battery's input-output performance.
Implementation Method 1
the electrolytic solution is considered to be degraded, by charging and discharging of the secondary battery, to forma coating called SEI (Solid Electrolyte Interphase) on the surface of a negative electrode
Implementation Method 2
a coating called SEI (Solid Electrolyte Interphase) on the surface of a negative electrode
Implementation Method 3
facilitates faster lithium ion passage
Data Source
AI summary
A method for producing a secondary battery including:an electrolytic solution containing a metal salt whose cation is an alkali metal, an alkaline earth metal, or aluminum and whose anion has a chemical structure represented by general formula (1) below, and a linear carbonate represented by general formula (2) below;a negative electrode;a positive electrode; anda coating on a surface of the negative electrode and/or the positive electrode, the coating containing S, O, and C,the method including forming the coating by performing a specific activation process on a secondary battery including the electrolytic solution, the negative electrode, and the positive electrode,(R1X1)(R2SO2)N general formula (1),R20OCOOR21 general formula (2).