Electrolyte Composition for Low-Temp Discharge and Oxidation Stability
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Solution Overview
Problem
Existing electrochemical apparatuses, such as lithium-ion batteries, face challenges in achieving concurrent improvements in high-temperature cycling capacity retention rate and low-temperature high-rate discharge capacity retention rate.
Innovation Solution
An electrolyte formulation comprising specific compounds of formula I and formula II, with defined mass percentages, forms a positive electrode interface passivation layer and enhances oxidation resistance, improving both low-temperature high-rate discharge capacity and high-temperature cycling capacity retention rates by reducing impedance and stabilizing electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrolyte components are added to improve low-temperature discharge performance, then low-temperature high-rate discharge capacity retention rate improves, but high-temperature cycling capacity retention rate deteriorates due to oxidation
Solution Approach 1:
Compound (II) acts as an intermediary protective agent that suppresses oxidative decomposition of the electrolyte components. It preferentially reacts with oxidative species or forms a protective interface that prevents direct oxidation of compound (I) and other electrolyte components. This intermediary action reduces harmful HF generation and maintains electrolyte stability at high temperatures while allowing compound (I) to effectively improve low-temperature discharge performance.
Solution Approach 2:
The patent converts the potential harmful effect of added electrolyte components (which could accelerate oxidation) into a beneficial outcome by carefully selecting compound (II) with strong oxidation resistance. The synergistic interaction between compound (I) and compound (II) transforms what could be a detrimental oxidative environment into a controlled interface formation process, where the passivation layer develops without excessive HF generation, thereby improving both low-temperature performance and high-temperature stability.
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 formulation effectively enhances the low-temperature high-rate discharge capacity and high-temperature cycling capacity retention rates of electrochemical apparatuses by forming a protective layer at the positive electrode interface and improving electrode stability, thereby optimizing performance across varying temperature conditions.
Implementation Method 1
the compound of formula I can form a positive electrode interface passivation layer of a lithium-containing inorganic compound rich in S and F elements at a positive electrode interface
Implementation Method 2
further reducing the positive electrode side impedance
Implementation Method 3
the compound of formula II has good oxidation resistance, can further improve an overall oxidation resistance of the electrolyte, suppress a situation where the compound of formula I accelerates oxidative decomposition of components in the electrolyte to generate HF
Implementation Method 4
improve positive electrode stability
Implementation Method 5
an ionic conductivity of the electrolyte can be enhanced
Implementation Method 6
a viscosity of the electrolyte can be further improved
Data Source
AI summary
An electrolyte includes a compound of formula Iand a compound of formula IIBased on a mass of the electrolyte, a mass percentage A of the compound of formula I satisfies 0.01%≤A≤70%, and a mass percentage B of the compound of formula II satisfies 2.0%≤B≤20%.