Silicon Electrolyte Additive for LiPF6 Side-Reaction Control
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Solution Overview
Problem
Lithium secondary batteries face issues with the reactivity of LiPF6, leading to solvent depletion, gas generation, and poor high-temperature performance due to side reactions, which affect their lifetime and safety.
Innovation Solution
Incorporating a silicon-based additive in the electrolyte, represented by Formula 1, which includes a silyl moiety that suppresses solvent decomposition, coordinates with water to reduce hydrolysis, and forms a stable film on electrodes, enhancing the battery's cycle lifetime and high-temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF6 is used as a lithium salt in the electrolyte, then ionic conductivity is improved, but side reactions occur leading to solvent depletion and gas generation
Solution Approach 1:
The patent introduces a silyl group-containing compound as an intermediary substance that mediates between LiPF6 and the electrolyte solvent. This additive preferentially reacts with LiPF6 to form a protective interface layer, preventing direct contact and harmful reactions between LiPF6 and the solvent, thus maintaining ionic conductivity while reducing solvent depletion and gas generation
Solution Approach 2:
The patent converts the harmful side reactions of LiPF6 into a beneficial protective mechanism. By allowing controlled initial reactions of LiPF6 with the silyl-containing additive, a stable protective film is formed on the electrode surface that subsequently prevents further harmful reactions, transforming the problematic reactivity into a protective function
2Power
If the battery operates at high temperature, then power output is improved, but lifetime characteristics deteriorate due to accelerated side reactions
Solution Approach 1:
The patent applies preliminary anti-action by introducing the silyl group-containing compound that proactively prevents high-temperature degradation before it occurs. This additive forms a thermally stable protective layer during initial cycles that acts as a barrier against thermal runaway and accelerates decomposition reactions, enabling the battery to maintain both power output and lifetime characteristics at elevated temperatures
3Use of energy by moving object
If organic electrolyte is used to achieve high voltage operation, then energy density is improved, but reactivity with lithium increases leading to safety issues
Solution Approach 1:
The silyl group-containing compound serves as an intermediary layer between the organic electrolyte and lithium. This additive forms a stable interfacial film that mediates the interaction, allowing the high-energy organic electrolyte to function while preventing direct harmful reactions with lithium, thus maintaining energy density while reducing safety risks
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 silicon-based additive improves the lithium secondary battery's cycle lifetime, reduces gas generation, and enhances high-temperature performance by forming a stable film on electrodes, thereby increasing the battery's conductivity and preventing overdischarging.
Implementation Method 1
coordinates with water to reduce hydrolysis
Implementation Method 2
forms a stable film on electrodes
Data Source
AI summary
An additive for a lithium secondary battery includes a compound represented by Formula 1 below, where R1 to R4 are as defined in the disclosure. An electrolyte for a lithium secondary battery includes: a lithium salt; a non-aqueous organic solvent; and the additive. A lithium secondary battery includes: a cathode; an anode; and the electrolyte.