Non-Aqueous Electrolyte Additive for Negative Electrode Interface Stability
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Solution Overview
Problem
Conventional lithium secondary battery electrolyte solutions suffer from low reductive cleavage stability, leading to decomposition and performance deterioration, particularly at the negative electrode-electrolyte interface, which affects battery lifespan and stability.
Innovation Solution
A non-aqueous electrolyte solution for lithium secondary batteries incorporating a lithium salt, an organic solvent, and a first additive represented by specific chemical formulas that form a carbon-oxygen single or double bond-based film, enhancing the stability of the negative electrode-electrolyte interface and reducing decomposition during charge and discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte solution is used, then battery can operate, but reductive cleavage stability is low causing electrolyte decomposition and lifespan reduction
Solution Approach 1:
The patent introduces a specific additive compound as an intermediary substance between the electrolyte and the negative electrode. This additive preferentially decomposes to form a stable SEI film that acts as a protective mediator, preventing direct contact and harmful reactions between the electrolyte and the negative electrode, thereby improving electrolyte stability and extending battery lifespan.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by adding a specific compound with defined molecular structure (formula 1) and concentration range (0.01-5 wt%). This parameter change transforms the electrolyte's interfacial properties, creating a more stable SEI film with higher reductive cleavage stability, which resolves the contradiction between operational functionality and long-term stability.
2Reliability
If electrolyte decomposition occurs, then SEI film forms on negative electrode, but this acts as resistive layer promoting performance deterioration
Solution Approach 1:
The patent applies preliminary anti-action by having the additive compound preferentially decompose during initial charging cycles to form a stable SEI film before the bulk electrolyte can decompose. This pre-formed protective layer prevents subsequent harmful decomposition reactions, blocking the formation of resistive layers and performance-deteriorating byproducts while maintaining interface stability.
Solution Approach 2:
The patent changes the decomposition characteristics of the electrolyte system by introducing an additive with specific molecular structure (formula 1) that has tailored electrochemical stability. This parameter change ensures that the additive decomposes at a different potential than the bulk electrolyte, forming a stable SEI film with lower resistance and better ionic conductivity, thus preventing harmful resistive layer formation.
3Reliability
If interface between negative electrode and electrolyte is unstable, then electrolyte depletion occurs, but this causes degeneration and breakdown of battery
Solution Approach 1:
The patent introduces the additive compound as an intermediary that stabilizes the negative electrode-electrolyte interface. This intermediary forms a protective SEI film that prevents direct harmful interactions, thereby reducing electrolyte depletion and preventing battery degeneration and breakdown, while maintaining sufficient electrolyte quantity throughout the battery lifecycle.
4Quantity of substance
If silicon-containing negative electrode is used, then capacity is high, but SEI film breaks due to volume change exposing unstable surface
Solution Approach 1:
The patent applies beforehand cushioning by having the additive compound form a robust, flexible SEI film during initial cycles that can accommodate the volume changes of silicon during lithiation and delithiation. This pre-formed protective layer acts as a cushion that prevents direct exposure of the unstable silicon surface, maintaining surface stability throughout charge-discharge cycles while preserving high lithium storage capacity.
Solution Approach 2:
The patent creates a composite SEI film structure consisting of the additive decomposition products and electrolyte decomposition products. This composite material combines the high capacity benefits of silicon with the stability provided by the additive-formed SEI layer, achieving both high lithium storage capacity and sustained surface stability through the synergistic combination of different material properties.
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 solution improves the lifespan characteristics of lithium secondary batteries by stabilizing the negative electrode-electrolyte interface, reducing decomposition, and maintaining performance at both room and high temperatures.
Implementation Method 1
the reductive cleavage stability of the electrolyte solution solvent is low, thereby causing lifespan reduction and electrolyte decomposition during storage. The decomposition reaction of the electrolyte solution forms an SEI film
Implementation Method 2
An electrolyte solution for a lithium secondary battery is composed of a lithium salt, an organic solvent which dissolves the lithium salt, and a functional additive
Data Source
AI summary
A non-aqueous electrolyte solution for a lithium secondary battery according to the present technology includes: a lithium salt; an organic solvent; and a first additive, and the first additive includes a compound represented by following chemical formula 1: Herein, R1 is a substituted or unsubstituted unsaturated hydrocarbon group having 2 to 20 carbon atoms, and R2 is one selected from the group consisting of hydrogen, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms and a substituted or unsubstituted cyclic alkyl group having 3 to 8 carbon atoms.