Phase-Separating Lithium Battery Electrolytes for Longer Cycle Life
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Solution Overview
Problem
Current electrolytes in lithium batteries undergo rapid degradation during repeated charge-discharge cycles, leading to limited cycle lifetimes and reduced performance.
Innovation Solution
Incorporating an electrolyte composition comprising a lithium salt, an organic solvent, and an aromatic hydrocarbon solvent with limited solubility, which induces phase separation, thereby reducing degradation and enhancing cycle life and low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional carbonate electrolytes are used in lithium batteries, then the batteries can operate with standard electrolyte composition, but the electrolytes undergo rapid degradation during repeated charge-discharge cycles resulting in limited cycle lifetimes
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing aromatic hydrocarbons (toluene, xylene, or trimethylbenzene) at specific concentrations (1-50 wt%) into the carbonate electrolyte system. This parameter modification fundamentally alters the electrolyte's stability characteristics, preventing rapid degradation during charge-discharge cycles and extending cycle lifetime while maintaining functional performance.
Solution Approach 2:
The patent creates a composite electrolyte system by combining conventional carbonate solvents (EC, DMC, DEC, EMC) with aromatic hydrocarbon components. This composite formulation leverages the beneficial properties of both material types: the carbonate solvents provide good ionic conductivity and solvation, while the aromatic hydrocarbons provide enhanced stability and reduced degradation, resulting in a synergistic electrolyte composition that resolves the contradiction between reliability and substance loss.
2Reliability
If aromatic hydrocarbon solvent is added to the electrolyte composition, then cycle lifetime increases, but the electrolyte may undergo phase separation at certain concentrations
Solution Approach 1:
The patent precisely controls the concentration parameter of aromatic hydrocarbon additives within specific ranges (1-50 wt%, with preferred ranges of 5-30 wt%). By optimizing this parameter, the electrolyte maintains homogeneous single-phase composition during operation. The patent identifies critical concentration thresholds that prevent phase separation while maximizing cycle lifetime benefits, demonstrating parameter optimization to resolve the contradiction between reliability improvement and compositional stability.
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 composition results in a substantial increase in cycle lifetime and reduces electrolyte degradation, improving battery performance and stability.
Implementation Method 1
an aromatic hydrocarbon solvent with limited solubility, which induces phase separation
Data Source
AI summary
The present invention relates generally to lithium batteries, and more specifically, to electrolyte compositions within lithium batteries. Some aspects of the invention are related to an electrolyte for a lithium battery. In some embodiments, the electrolyte comprises a lithium salt, an organic solvent, and an aromatic hydrocarbon solvent that is different from the organic solvent. The aromatic hydrocarbon solvent may have limited solubility in the organic solvent and/or a limited solubility for lithium salt, e.g., such that the aromatic hydrocarbon solvent is capable of inducing phase separation of the electrolyte when present in a certain amount. In one set of embodiments, an electrolyte comprising one or more aromatic hydrocarbon may lead to an enhanced battery cycle life, reduced rate of electrolyte degradation, and improved low temperature performance. The subject matter disclosed herein involves, in some cases, the use of the electrolyte in a lithium battery.