Non-aqueous Electrolyte S=O Additive for Anode Stability
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Solution Overview
Problem
Lithium secondary batteries face issues with high reactivity between propionate-based ester compounds and graphite-based anodes, leading to excessive side reactions and reduced battery performance, especially at high temperatures, and poor low-temperature conductivity due to the use of ethylene carbonate-based solvents.
Innovation Solution
Incorporating a compound with an S=O group, such as cyclic sulfite, saturated sultone, unsaturated sultone, or non-cyclic sulfone, into the non-aqueous electrolyte, along with a propionate-based ester compound and a carbonate, to form a stable electrode film and reduce reactivity with the anode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If propionate-based ester compounds are used in the electrolyte, then low-temperature conductivity is improved, but reactivity with graphite-based anodes increases causing excessive side reactions
Solution Approach 1:
The patent introduces a compound with S=O group as an intermediary substance that mediates between the propionate-based ester and the graphite anode. This compound forms a protective film on the anode surface first, preventing direct contact and harmful reactions between the ester and anode, while still allowing ionic conductivity to pass through.
Solution Approach 2:
The compound with S=O group performs preliminary protective action by forming a stable interface film on the anode surface before the propionate-based ester can cause harmful side reactions. This preliminary film acts as a barrier that prevents the ester from reacting with the anode while maintaining ion transport.
2Stability of the object's composition
If ethylene carbonate-based solvents are used in the electrolyte, then electrochemical stability is improved, but low-temperature conductivity deteriorates
Solution Approach 1:
The patent merges ethylene carbonate-based solvents with propionate-based ester compounds and compounds containing S=O groups to create a multi-component electrolyte system. This combination leverages the electrochemical stability of ethylene carbonate while the propionate ester and S=O compound improve low-temperature conductivity and form protective films.
Solution Approach 2:
The electrolyte is designed as a composite system containing multiple components: ethylene carbonate for stability, propionate-based esters for low-temperature conductivity, and S=O compounds for forming protective films. This composite approach allows the electrolyte to simultaneously achieve stability and low-temperature performance.
3Use of energy by moving object
If the battery is left at high temperature in fully charged state, then electrochemical energy increases, but SEI film breaks down causing continuous gas generation and increased internal pressure
Solution Approach 1:
The compound with S=O group provides beforehand cushioning by forming a more thermally stable protective film on the anode surface. This film acts as a cushion that prevents the breakdown of the SEI film at high temperatures, thereby preventing continuous gas generation and internal pressure increase during high-temperature storage.
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 use of a compound with an S=O group in the electrolyte improves the battery's life cycle, high-rate discharge characteristics, and low-temperature performance while maintaining high-temperature stability, reducing reductive reactions and impedance.
Implementation Method 1
Incorporating a compound with an S=O group, such as cyclic sulfite, saturated sultone, unsaturated sultone, or non-cyclic sulfone, into the non-aqueous electrolyte, along with a propionate-based ester compound and a carbonate, to form a stable electrode film and reduce reactivity with the anode.
Implementation Method 2
The use of a compound with an S=O group in the electrolyte improves the battery's life cycle, high-rate discharge characteristics, and low-temperature performance while maintaining high-temperature stability, reducing reductive reactions and impedance.
Implementation Method 3
Lithium ions coming out from a cathode active material such as lithium metal oxide during an initial charging process of a lithium secondary battery are moved to an anode active material such as graphite and then intercalated between layers of the anode active material.
Implementation Method 4
Lithium ions coming out from a cathode active material such as lithium metal oxide during an initial charging process of a lithium secondary battery are moved to an anode active material such as graphite and then intercalated between layers of the anode active material.
Implementation Method 5
The SEI film plays the role of an ion tunnel, which allows only lithium ions to pass. Due to the ion tunnel effects, the SEI film prevents organic solvent having high molecular weight from moving together with lithium ions in the electrolyte and being inserted into layers of the anode active material.
Implementation Method 6
Due to the high reactivity of lithium, the electrolyte reacts with carbon of the anode active material on the surface of the anode active material, such as graphite, thereby generating compounds such as Li2CO3, Li2O and LiOH.
Implementation Method 7
in a thin angled battery, while the above SEI film is formed, gas such as CO, CO2, CH4 and C2H6, generated by decomposition of a carbonate-based solvent, increases the battery thickness during the charging process.
Implementation Method 8
an electrolyte prepared by dissolving a suitable amount of lithium salt in a mixed organic solvent
Data Source
AI summary
A non-aqueous electrolyte includes (i) a compound having an S=O group; (ii) a mixed organic solvent containing a carbonate and an ester compound; and (iii) an electrolyte salt, wherein the compound having an S=O group is at least one compound selected from the group consisting of cyclic sulfite, saturated sultone, unsaturated sultone, and non-cyclic sulfone. Also, an electrochemical device includes a cathode, an anode and the above non-aqueous electrolyte.