Electrolyte Additives for Li-Ion Capacity Retention Across Temperatures
Find Innovative SolutionsGenerate Solutions
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, within defined mass percentages, forms a positive electrode interface passivation layer and enhances oxidation resistance, improving both low-temperature high-rate discharge and high-temperature cycling capacity retention rates by reducing impedance and stabilizing electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the positive electrode interface passivation layer is formed to improve low-temperature discharge performance, then the positive electrode side impedance decreases, but the oxidative decomposition of electrolyte components accelerates
Solution Approach 1:
The patent applies preliminary anti-action by introducing compound II (with strong oxidation resistance) and compound III (with fluorine-containing groups) into the electrolyte formulation before operation. These compounds preemptively counteract the oxidative decomposition that would otherwise be accelerated by the passivation layer formation. Compound II suppresses HF generation through its oxidation resistance, while compound III provides additional protective effects at the electrode interface, thereby preventing the harmful side effects before they can occur during battery operation.
Solution Approach 2:
The patent uses compound III (fluorine-containing additive) as an intermediary substance that mediates between the passivation layer formation and oxidative decomposition processes. This compound preferentially reacts with trace water and impurities, and forms stable fluorinated species that inhibit HF generation. The intermediary action of compound III allows the beneficial passivation layer to form while simultaneously blocking the pathway to oxidative decomposition and HF generation, thus resolving the contradiction between improved low-temperature performance and reduced oxidative harm.
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 improves low-temperature high-rate discharge capacity retention and high-temperature cycling capacity retention rates by forming a protective layer at the positive electrode interface and enhancing electrode stability, thereby optimizing the electrochemical apparatus's 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
Implementation Method 4
protect the positive electrode, and improve a high-temperature cycling capacity retention rate of the electrochemical apparatus
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 I and a compound of formula II Based 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%.