Lithium Battery Electrolyte Additives for Low-DCR Interface Films
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Solution Overview
Problem
Lithium-ion batteries face issues with side reactions at the anode and cathode interfaces during cycling, leading to increased direct current resistance (DCR), consumption of active lithium, and degradation of power and cycling performance.
Innovation Solution
An electrolyte formulation comprising additives with trimethylsilyl, lithium ion, and ester groups is used to form dense, stable films at the anode and cathode interfaces, suppressing side reactions and reducing DCR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte formulations are used, then basic battery operation is maintained, but side reactions occur at electrode interfaces leading to increased DCR and performance degradation
Solution Approach 1:
The patent introduces film-forming additives (trimethylsilyl group compound, lithium ion compound, and ester group compound) as intermediary substances that mediate between the electrolyte and electrode interfaces. These additives preferentially react to form protective interface films that prevent direct contact between the electrolyte and electrode materials, thereby suppressing side reactions while maintaining basic battery operation
Solution Approach 2:
The patent employs a composite additive system combining three different types of compounds (trimethylsilyl group compound, lithium ion compound, and ester group compound) in specific weight ratios. This composite approach creates synergistic effects where each component contributes different functionalities to the interface film, achieving superior protection against side reactions compared to single additives
2Power
If no interface film forming additives are used, then electrolyte composition is simple, but initial DCR is high and power performance is poor
Solution Approach 1:
The patent optimizes the weight ratios of the three additive components (trimethylsilyl group compound: 0.01-0.5%, lithium ion compound: 0.005-0.1%, ester group compound: 0.01-0.5%) to achieve the desired balance between initial power performance and electrolyte composition complexity. By precisely controlling these parameter ranges, the patent forms interface films with optimal conductivity without excessive additive content
3Reliability
If interface films are formed to suppress side reactions, then cycling performance improves, but film formation consumes active lithium
Solution Approach 1:
The patent creates interface films with different compositions at different electrode interfaces by selecting specific additive combinations. The trimethylsilyl group compound and lithium ion compound preferentially form films at the cathode interface, while the ester group compound contributes to anode interface film formation. This localized film formation suppresses side reactions at each interface while minimizing bulk lithium consumption
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 enhances battery power, cycling, and storage performance by forming uniform films that reduce impedance and prevent electrolyte decomposition, thereby improving overall battery performance.
Implementation Method 1
The first additive containing a trimethylsilyl group can participate in anode interface film formation during the formation and cyclic storage processes of an electrochemical energy storage apparatus, effectively reducing the initial direct current resistance (DCR) of the secondary battery
Implementation Method 2
The third additive containing an ester group can also participate in anode interface film formation during the formation and cyclic storage processes of an electrochemical energy storage apparatus, effectively suppressing the occurrence of side reactions at the anode interface
Implementation Method 3
The second additive containing lithium ions can participate in cathode interface film formation, effectively suppressing the occurrence of side reactions at the cathode interface during the cyclic storage process of an electrochemical energy storage apparatus
Data Source
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AI summary
The present application provides an electrolyte, a lithium secondary battery, and an electric apparatus. The electrolyte includes additives, where the additives include a first additive containing a trimethylsilyl group, a second additive containing lithium ions, and a third additive containing an ester group. By adding these three additives to the electrolyte, the present application can effectively reduce the initial DCR of the battery, improve initial power performance, and enhance the cycling performance and storage performance of the battery.