Non-Aqueous Electrolyte Additive for Stable SEI in Lithium Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face issues with degradation of positive electrodes and negative electrodes due to side reactions and electrolyte deterioration, leading to increased gas generation and swelling, particularly at high temperatures, which affect lifespan and storage characteristics.
Innovation Solution
A non-aqueous electrolyte containing a compound with an acetimidoyl group coupled to a silyl group, represented by Formula 1, is used to form a stable solid electrolyte interphase (SEI) on the negative electrode, scavenging HF and minimizing resistance, thereby enhancing high-temperature cycle and storage properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the potential of the positive electrode is increased to achieve higher voltage operation, then the energy density and power output are improved, but the side reactions between the electrolyte and electrode surface accelerate, causing transition metal ion elution and SEI degradation
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate additive as an intermediary substance that mediates the interaction between the electrolyte and electrode surfaces. This additive preferentially reacts with transition metal ions and HF to form a protective interface layer, preventing direct harmful interactions while allowing the high-voltage operation to proceed. The additive acts as a buffer that protects the electrode-electrolyte interface from degradation.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating fluorinated cyclic carbonate compounds with specific molecular structures ( Formula 1). This parameter change alters the electrochemical window and stability characteristics of the electrolyte system, enabling it to withstand higher potentials without decomposing. The fluorine substitution and cyclic carbonate structure specifically enhance the electrolyte's resistance to oxidation at high potentials.
2Speed
If the battery is operated at high temperatures to improve reaction kinetics and charging speed, then the power delivery is enhanced, but the gas generation increases and swelling phenomenon occurs due to SEI degradation
Solution Approach 1:
The fluorinated cyclic carbonate additive serves as a thermal buffer and protective intermediary at the electrode-electrolyte interface. At elevated temperatures, it preferentially decomposes or reacts to form a stable protective layer that prevents uncontrolled side reactions and gas generation. The additive absorbs thermal stress and prevents direct thermal degradation of the SEI film.
Solution Approach 2:
The patent applies beforehand cushioning by having the fluorinated cyclic carbonate additive pre-form a protective interface layer on the electrode surfaces before thermal degradation can occur. This pre-formed protective layer acts as a cushion that prevents direct contact between the electrolyte and electrode at high temperatures, thereby preventing gas-generating side reactions and SEI collapse.
3Reliability
If conventional electrolyte additives are used to form SEI films on the negative electrode, then some protection is provided, but the SEI passivation capability degrades over time due to transition metal ion elution and HF generation
Solution Approach 1:
The patent creates a composite protective interface structure by combining fluorinated cyclic carbonate additives with conventional SEI-forming components. This composite approach produces a multi-layered or multi-component SEI film that integrates the benefits of both conventional additives (SEI formation) and fluorinated compounds (HF scavenging, transition metal ion complexation). The synergistic combination provides enhanced long-term stability.
Solution Approach 2:
The patent converts harmful substances (transition metal ions and HF) into beneficial protective functions. Instead of allowing these substances to degrade the SEI and electrodes, the fluorinated cyclic carbonate additive captures and neutralizes them, transforming them into stable complexes or protective interface components. This converts potential degradation agents into protective elements that extend battery life.
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 compound in the non-aqueous electrolyte stabilizes the electrode-electrolyte interface at high temperatures, improving the lithium secondary battery's lifespan and storage characteristics by suppressing degradation and resistance.
Implementation Method 1
the compound represented by Formula 1 of the present disclosure has a CF3 group near the Si—N bond and has high binding energy to HF, and thus can effectively scavenge HF
Implementation Method 2
the compound represented by Formula 1 may form a stable solid electrolyte interphase (SEI) on a surface of the negative electrode
Data Source
AI summary
Provided is a non-aqueous electrolyte comprising a lithium salt; an organic solvent; and a compound represented by Formula 1 as an additive:wherein in Formula 1, R1 may be an alkyl group having 1 to 5 carbon atoms and optionally being substituted with fluorine, an aryl group having 6 to 8 carbon atoms and optionally being substituted with fluorine, or a nitrile group; and R2 to R4 are each independently an alkyl group having 1 to 5 carbon atoms.