Non-Aqueous Li-Ion Electrolyte for Cathode Stability Under Cycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion battery life cycles deteriorate due to degradation of the cathode active material structure, which can be improved by using electrolyte fluids that limit this degradation.
Innovation Solution
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 a lithium salt and additive such as lithium difluoro(oxalato)borate (LiDFOB).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte fluids are used, then the battery can operate, but the cathode active material structure degrades over time reducing battery life
Solution Approach 1:
The electrolyte fluid is formulated with specific carbonate solvents (DMC, EMC, PC, EC) and lithium salts before battery operation begins. This preliminary composition design creates a stable electrochemical environment that prevents cathode material degradation from the start, rather than attempting to repair damage after it occurs. The pre-configured electrolyte composition establishes protective conditions for the cathode structure throughout the battery's operational life.
Solution Approach 2:
The invention changes the chemical composition parameters of the electrolyte fluid by specifying precise weight percentages of different carbonate solvents (DMC: 10-70%, EMC: 10-70%, PC: 2-20%, EC: 5-40%) and lithium salts. These parameter changes optimize the electrolyte's ability to maintain cathode material stability, directly addressing the degradation issue by tuning the chemical properties of the electrolyte to be more compatible with cathode structures.
2Stability of the object's composition
If the electrolyte composition is optimized for stability, then cathode material degradation is limited, but the discharge capacity and energy retention must be maintained
Solution Approach 1:
The electrolyte fluid employs a composite composition combining multiple carbonate solvents (DMC, EMC, PC, EC) with lithium salts and additives. This composite approach leverages the complementary strengths of each component: DMC and EMC provide good ion conductivity and stability, while PC and EC enhance cathode material compatibility. The synergistic combination maintains both cathode structure stability and high discharge capacity, resolving the trade-off between stability and energy performance.
Solution Approach 2:
The electrolyte formulation applies different functional qualities to different components: DMC and EMC contribute to overall stability and cycle life, while PC and EC specifically target cathode interface stability. The lithium salts provide ionic conductivity, and additives like LiDFOB, SN, PS, and HTCN provide localized protection at the cathode surface. This distributed functional assignment allows the electrolyte to simultaneously achieve cathode protection and maintain high energy performance.
3Productivity
If the battery operates for increased cycle counts, then more energy can be delivered, but internal resistance increases and performance deteriorates
Solution Approach 1:
The electrolyte is pre-formulated with stable carbonate components and protective additives before the battery begins cycling. This preliminary configuration creates a robust electrochemical environment that resists the formation of resistive layers on the cathode surface during cycling. The pre-configured composition prevents internal resistance buildup from the outset, enabling the battery to maintain low resistance even after increased cycle counts and continued high productivity.
Solution Approach 2:
The invention optimizes the electrolyte composition parameters by adjusting the ratios of carbonate solvents and adding specific lithium salts and additives. These parameter changes enhance the electrolyte's ability to maintain stable ionic conductivity over time, preventing the increase in internal resistance that typically occurs with cycling. The optimized composition ensures that energy loss remains minimal even after extended operational cycles.
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 electrolyte fluid composition enhances discharge capacity, energy retention, and reduces internal resistance, particularly at increased cycle counts, thereby improving the overall performance and longevity of lithium-ion battery cells.
Implementation Method 1
An electrolyte fluid as described herein is disposed between the cathode and anode
Implementation Method 2
the electrolyte fluid includes 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.