Carbonate Electrolyte Additives for Li-Ion Charging Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lithium ion secondary batteries experience capacity deterioration during charging due to changes in the positive electrode's crystal structure and increased reaction resistance at low potentials.
Innovation Solution
Incorporating a nonaqueous electrolytic solution containing carbonates as a solvent and specific additive agents like 2-vinylpyridine, vinyl benzoate, or 1-ethyl-3-methylimidazolium derivatives into the electrolyte to enhance the irreversible capacity of the negative electrode, forming a thicker coating film that stabilizes the positive electrode potential and reduces reaction resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the positive electrode potential is lowered during charging, then the charging capacity increases, but the reaction resistance increases and capacity deterioration occurs
Solution Approach 1:
The patent introduces a specific electrolyte composition containing cyclic carbonate and chain carbonate in a volume ratio of 20:80 to 80:20 as an intermediary medium. This electrolyte formulation mediates between the electrode and lithium ions, enabling efficient ion transport while maintaining stable electrode potential and preventing excessive reaction resistance during charging.
Solution Approach 2:
The patent changes the physical-chemical parameters of the electrolyte by specifying precise volume ratios of cyclic carbonate to chain carbonate (20:80 to 80:20). This parameter optimization allows the electrolyte to maintain appropriate viscosity, conductivity, and solvation capability, thereby enabling low potential charging without excessive reaction resistance.
2Quantity of substance
If the positive electrode potential is lowered during charging, then the charging capacity increases, but the crystal structure stability deteriorates
Solution Approach 1:
The electrolyte composition acts as a protective intermediary between the positive electrode and the aggressive low-potential charging conditions. The specific ratio of cyclic to chain carbonate provides optimal solvation for lithium ions while stabilizing the electrode's crystal structure during charging.
Solution Approach 2:
The patent uses a composite electrolyte system combining cyclic carbonate and chain carbonate in specific proportions. This composite electrolyte formulation provides both the high dielectric constant needed for ion dissociation (from cyclic carbonate) and the low viscosity for ion mobility (from chain carbonate), thereby stabilizing the electrode structure during charging.
3Reliability
If a thicker coating film is formed on the negative electrode, then the positive electrode potential stabilizes, but the irreversible capacity increases
Solution Approach 1:
The patent optimizes the electrolyte composition parameters (cyclic to chain carbonate volume ratio) to control the thickness and quality of the coating film formed on the negative electrode. By adjusting this ratio, the system achieves a balance where the coating film is thick enough to stabilize the positive electrode potential but thin enough to minimize irreversible capacity loss.
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 suppresses capacity deterioration and shortens charging time by maintaining a higher positive electrode potential, thereby preventing excessive reaction resistance and extending battery life.
Implementation Method 1
the nonaqueous electrolytic solution contains a nonaqueous solvent and an additive agent A... it is possible to suppress the capacity deterioration at the time when the electric charge is performed on the electric storage device
Data Source
AI summary
A technique is provided that can suppress a capacity deterioration when an electric charge is performed on an electric storage device. The herein disclosed electric storage device includes a nonaqueous electrolytic solution. The nonaqueous electrolytic solution contains a nonaqueous solvent and an additive agent A. The nonaqueous solvent is carbonates. The additive agent A is at least one of 2-vinylpyridine, vinyl benzoate, 3,4-thiophenedicarboxylic anhydride, 1-ethyl-3-methylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium methylphosphonate, and 1-ethyl-3-methylimidazolium bis(perfluoroethylsulfonyl)imide.