Lithium-Ion Battery Electrolyte Composition for Long Cycle Retention
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face challenges in maintaining cycle characteristics after several thousand cycles, which have not been adequately addressed in existing technologies.
Innovation Solution
A lithium ion secondary battery design comprising a positive electrode with a specific ratio of positive to negative electrode capacity, adjusted nominal voltage, and a non-aqueous electrolyte solution containing LiPF6 and lithium imide salt, with a carbonate-based solvent, optionally including a surplus electrolyte solution, to enhance cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte formulations are used, then initial battery performance is adequate, but cycle characteristics deteriorate after several thousand cycles
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing specific additives (cyclic carboxylate and cyclic carbonate esters) and optimizing the ratio of electrolyte salts to improve long-term cycle characteristics while maintaining initial performance
Solution Approach 2:
The patent creates a composite electrolyte system by combining multiple electrolyte salts (lithium hexafluorophosphate and lithium imide salt) with specific cyclic additives to achieve synergistic effects that enhance both initial performance and long-term durability
2Reliability
If electrolyte concentration is increased to improve cycle characteristics, then long-term stability improves, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the concentration parameters within practical ranges (electrolyte salt: 0.5-2.0 mol/L, cyclic additive: 0.01-0.5 mol/L) to achieve improved cycle characteristics without excessive complexity in formulation or manufacturing
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 battery design significantly improves cycle characteristics by suppressing the decrease in capacity retention rate after multiple charging and discharging cycles, maintaining stable performance over extended use.
Implementation Method 1
the non-aqueous electrolyte solution comprises LiPF6 and a lithium imide salt as an electrolyte
Implementation Method 2
comprises a carbonate-based solvent as a solvent
Data Source
Figure 1~2
Figure 3
AI summary
[Problem] To provide a non-aqueous electrolyte secondary battery in which the decrease in cycle characteristics is improved as compared with conventional non-aqueous electrolyte secondary batteries. [Solution] A lithium ion secondary battery, which comprises a positive electrode comprising a positive electrode active material, a negative electrode, and a non-aqueous electrolyte solution, wherein the non-aqueous electrolyte solution comprises LiPF6 and a lithium imide salt as an electrolyte, and comprises a carbonate-based solvent as a solvent, the lithium ion secondary battery comprises or does not comprise a surplus electrolyte solution, the ratio of the positive electrode capacity to the negative electrode capacity is adjusted to less than 1, the nominal voltage is adjusted to less than 3.6 V, and the total content of LiPF6 and lithium imide salt comprised in the non-aqueous electrolyte solution per unit battery capacity and the ratio of the positive electrode capacity to the negative electrode capacity are adjusted to satisfy a specific relationship.