Lithium Cell Electrolyte Additive Suppresses Voltage Delay
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lithium primary cells with iron disulfide (FeS2) cathodes face issues of lithium passivation and voltage delay due to the use of ethylene carbonate/propylene carbonate electrolyte solvent mixtures, which reduce cell performance and reliability.
Innovation Solution
A nonaqueous electrolyte system using cyclic organic carbonates such as ethylene carbonate, propylene carbonate, and dimethoxyethane, with the addition of elemental iodine or bromine, which reduces lithium passivation and voltage delay, stabilizes the cathode binder, and maintains electrochemical reaction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ethylene carbonate/propylene carbonate electrolyte solvent mixtures are used, then the electrochemical reaction efficiency is maintained, but lithium passivation and voltage delay occur which reduce cell performance and reliability
Solution Approach 1:
The patent converts the harmful effect of lithium passivation into a beneficial protective layer by controlling the formation of a stable solid electrolyte interface (SEI) layer through the use of cyclic carbonate co-solvent. The passivation that was previously harmful is now harnessed to create a protective barrier that prevents further detrimental reactions while maintaining electrochemical performance.
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by introducing cyclic carbonate co-solvent (1,3-propanesultone or 1,4-butanesultone) at specific concentrations (0.1-5% by weight). This parameter change modifies the electrolyte's properties to reduce lithium passivation and eliminate voltage delay while maintaining reaction efficiency.
2Duration of action of stationary object
If conventional electrolyte systems are used, then the cell structure is simple, but the service life is reduced due to lithium passivation and voltage delay
Solution Approach 1:
The patent extends service life by changing the electrolyte composition parameters - specifically adding cyclic carbonate co-solvent (1,3-propanesultone or 1,4-butanesultone) at controlled concentrations (0.1-5% by weight). This parameter modification reduces lithium passivation and voltage delay, thereby extending the operational duration of the cell.
Solution Approach 2:
The patent creates a composite electrolyte system by combining conventional carbonate solvents (dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate) with cyclic carbonate co-solvent (1,3-propanesultone or 1,4-butanesultone). This composite electrolyte formulation synergistically improves service life while managing the complexity through defined composition ratios.
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 proposed electrolyte system significantly reduces lithium passivation and voltage delay, enhancing the performance and service life of lithium primary cells by maintaining consistent voltage and improving the electrochemical reaction rate.
Implementation Method 1
The FeS2 theoretical capacity is based on a 4 electron transfer from 4Li per FeS2 to result in reaction product of elemental iron Fe and 2Li2S
Implementation Method 2
electrolyte comprising a lithium salt and nonaqueous solvent
Implementation Method 3
A nonaqueous electrolyte system using cyclic organic carbonates such as ethylene carbonate, propylene carbonate, and dimethoxyethane, with the addition of elemental iodine or bromine, which reduces lithium passivation and voltage delay
Implementation Method 4
nonaqueous electrolyte system using cyclic organic carbonates such as ethylene carbonate, propylene carbonate, and dimethoxyethane
Data Source
AI summary
A primary cell having an anode comprising lithium and a cathode comprising iron disulfide (FeS2) and carbon particles. The electrolyte comprises a lithium salt dissolved in a nonaqueous solvent mixture which contains an additive, preferably iodine, suppressing voltage delay. A cathode slurry is prepared comprising iron disulfide powder, carbon, binder, and liquid solvent. The mixture is coated onto a conductive substrate and solvent evaporated leaving a dry cathode coating on the substrate. The anode and cathode can be spirally wound with separator therebetween and inserted into the cell casing with electrolyte then added.