Lithium-Ion Electrolyte Composition for Cathode Degradation Control
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Solution Overview
Problem
Lithium-ion battery life cycles deteriorate due to cathode active material degradation, which can be mitigated by using electrolyte fluids that limit this degradation.
Innovation Solution
The use of an electrolyte fluid with a solvent comprising dimethyl carbonate (DMC) and ethylmethylcarbonate (EMC) in specific weight percentages, along with propylene carbonate (PC) and ethylene carbonate (EC), and lithium salts and additives such as lithium difluoro (oxalato) borate (LiDFOB) to enhance stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If conventional electrolyte fluids are used, then battery capacity is maintained, but cathode active material degradation occurs leading to reduced battery life
Solution Approach 1:
The electrolyte fluid is formulated with specific additives (LiDFOB, SN, PS, HTCN) that proactively form protective films on the cathode active material surface before degradation can occur. This preliminary protective action prevents direct contact between the electrolyte and cathode material, thereby extending battery life while maintaining reliability.
Solution Approach 2:
The invention uses a composite electrolyte formulation combining multiple carbonate solvents (DMC, EMC, PC, EC) with lithium salts and specialized additives. This composite approach creates synergistic effects where each component contributes specific properties: DMC/EMC provide high dielectric constant for lithium salt dissolution, while PC/EC provide low volatility and film-forming capabilities, collectively enhancing both battery life and cathode stability.
2Reliability
If electrolyte additives are added to improve stability, then cathode degradation is reduced, but electrolyte composition complexity increases
Solution Approach 1:
The invention optimizes the concentration parameters of each electrolyte component within specific ranges: DMC 10-70 wt%, EMC 10-70 wt%, PC 2-20 wt%, EC 5-40 wt%, and additives at 0.1-5 wt% each. By controlling these parameters within defined boundaries, the formulation achieves effective cathode protection while managing composition complexity through systematic parameter optimization rather than arbitrary component addition.
3Productivity
If DMC and EMC are used as primary solvents, then discharge capacity is improved, but viscosity control becomes challenging
Solution Approach 1:
The electrolyte formulation applies local quality differentiation by assigning specific functional roles to different solvent components: DMC and EMC (50-80 wt% combined) provide high dielectric constant for superior lithium salt dissolution and high discharge capacity, while PC and EC (20-50 wt% combined) provide low viscosity and high ionic conductivity. This localized functional assignment allows each component to optimize its specific property while the mixture achieves balanced overall performance.
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 electrolyte composition improves discharge capacity, energy retention, and reduces internal resistance, particularly at increased cycle counts, thereby extending the lifespan of lithium-ion batteries.
Implementation Method 1
An electrolyte fluid as described herein is disposed between the cathode and anode
Implementation Method 2
a lithium salt selected from LiPF6, LiBF4, LiClO4, LiSO3CF3, LiN(SO2F)2, LiN(SO2CF3)2, LiBC4O8, Li[PF3(C2CF5)3], LiC(SO2CF3)3, and a combination thereof
Data Source
AI summary
This disclosure relates generally to battery cells, and more particularly, electrolyte solvents for use in lithium-ion battery cells.