Lithium Battery Electrolyte Additive for HF Scavenging and SEI Stability
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Solution Overview
Problem
Lithium secondary batteries face issues with self-discharge and increased resistance due to transition metal ion dissolution and electrolyte decomposition at high temperatures, which affect their stability and lifespan.
Innovation Solution
An electrolyte composition for lithium secondary batteries including a lithium salt, an organic solvent, and a specific additive compound represented by Formula 1, which scavenges Lewis acid by-products like HF and PF5, reducing the decomposition reaction and transition metal ion dissolution, thereby forming a stable solid electrolyte interphase and minimizing resistance increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the battery is operated at high temperatures, then the energy density and power output are improved, but electrolyte decomposition and transition metal ion dissolution occur, leading to increased resistance and self-discharge
Solution Approach 1:
A heterocyclic compound additive is introduced as an intermediary substance between the electrolyte and electrode. This additive preferentially reacts with decomposition products and transition metal ions, forming a protective interface layer that prevents direct harmful interactions while allowing the battery to operate at high temperatures for improved power output
2Power
If the battery is operated at high temperatures, then the energy density and power output are improved, but transition metal ions dissolve and re-deposit on the positive electrode, increasing resistance
Solution Approach 1:
The heterocyclic compound additive transforms the harmful effect of transition metal ion dissolution into a beneficial protective mechanism. The additive reacts with dissolved metal ions to form stable complexes that are deposited as a protective layer on the electrode, converting the harmful dissolution process into a beneficial surface modification that reduces resistance
3Power
If the battery is operated at high temperatures, then the energy density and power output are improved, but transition metal ions electrodeposit on the negative electrode, causing self-discharge
Solution Approach 1:
The heterocyclic compound acts as a mediator that intercepts transition metal ions before they can reach and electrodeposit on the negative electrode. The additive forms stable complexes with the metal ions in the electrolyte bulk, preventing their migration to the electrode surface and eliminating the self-discharge mechanism
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 composition effectively suppresses electrolyte decomposition and transition metal ion dissolution, enhancing the high-temperature life and resistance characteristics of lithium secondary batteries by forming a stable SEI and scavenging Lewis acid by-products, leading to improved capacity retention and reduced resistance.
Implementation Method 1
a compound represented by Formula 1, which has a structure similar to that of a cyclic carbonate and has at least one hydrogen atom bonded to a carbon atom adjacent to a carbonyl group and scavenges Lewis acid by-products such as HF and PF5
Implementation Method 2
The electrolyte causes a reduction decomposition reaction on a negative electrode interface during an activation process of the battery to form a solid electrolyte interphase (SEI). The SEI suppresses additional decomposition of an electrolyte solution and may transmit lithium ions.
Implementation Method 3
an electrolyte that becomes a medium for transferring lithium ions
Data Source
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AI summary
The present invention provides an electrolyte for a lithium secondary battery, which includes a lithium salt, an organic solvent, and a compound represented by Formula 1, and a lithium secondary battery including the same.