Lithium Battery Electrolyte Additive for Stable CEI at High Temperature
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Solution Overview
Problem
Lithium secondary batteries face challenges with chemical stability and operational reliability, particularly at high temperatures, due to side reactions between the electrolyte solution and electrodes, leading to increased internal resistance and capacity degradation.
Innovation Solution
An electrolyte solution for lithium secondary batteries is developed, comprising an organic solvent, a lithium salt, and a pentaerythritol diphosphite-based compound with specific substituents, which forms a stable cathode-electrolyte interphase, suppressing side reactions and facilitating the removal of hydrogen fluoride, thereby enhancing chemical stability and operational reliability at both high and low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte solutions are used in lithium secondary batteries, then the batteries can operate at high voltage and high capacity, but side reactions between the electrolyte and electrodes accelerate at high temperatures, causing increased internal resistance and capacity degradation
Solution Approach 1:
The patent introduces a cathode electrolyte interphase (CEI) layer formed by specific additives (vinylene carbonate and fluoroethylene carbonate) as an intermediary between the cathode and the bulk electrolyte. This CEI layer acts as a protective barrier that prevents direct contact and harmful side reactions between the electrolyte and cathode materials, especially at high temperatures, thereby improving operational reliability without sacrificing battery performance
Solution Approach 2:
The patent modifies the electrolyte composition by adjusting the ratio and types of carbonate solvents (EC, EMC, DEC) and adding specific cyclic carbonate additives (VC and FEC) in optimized concentrations. These parameter changes in the electrolyte formulation enable the formation of a stable CEI layer that suppresses high-temperature side reactions while maintaining low-temperature performance and high-voltage operation
2Stability of the object's composition
If the electrolyte solution is improved to suppress side reactions, then chemical stability improves, but the complexity of electrolyte formulation increases
Solution Approach 1:
The patent employs a composite electrolyte formulation combining multiple carbonate solvents (EC, EMC, DEC) with specific cyclic carbonate additives (VC and FEC) at optimized ratios. This composite approach creates synergistic effects where each component contributes specific properties: the carbonate solvents provide bulk conductivity while the cyclic carbonates form protective interphase layers, achieving enhanced chemical stability without excessive formulation complexity
Solution Approach 2:
The patent optimizes specific parameters in the electrolyte formulation, including the concentration ranges of each solvent and additive (e.g., VC at 0.1-5 wt%, FEC at 0.1-5 wt%), and the ratio of cyclic to chain carbonates. By carefully controlling these parameters, the patent achieves stable CEI formation and suppressed side reactions while maintaining a practical and manufacturable electrolyte composition
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 solution improves high-temperature storage properties by retaining capacity, suppressing internal resistance increases, and maintaining charge/discharge capacities, while also providing improved low-temperature performance by stabilizing the cathode structure and reducing internal resistance.
Implementation Method 1
The pentaerythritol diphosphite-based compound including the specific substituent may form a cathode-electrolyte interphase (CEI) having improved stability on a surface of a cathode
Implementation Method 2
hydrogen fluoride (HF) in the electrolyte solution may be easily removed
Data Source
AI summary
An electrolyte solution for a lithium secondary battery includes an organic solvent, a lithium salt, and a pentaerythritol diphosphite-based compound including at least one substituent selected from the group consisting of a silyl group, a sulfonyl group, a phosphoryl group and a phosphino group. A lithium secondary including the electrolyte solution is provided.