Cathode Electrolyte Composition for High-Temp Storage and Cold Discharge
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Solution Overview
Problem
Existing electrochemical apparatuses face degradation in low-temperature discharge performance while improving high-temperature performance, necessitating a solution that maintains both high-temperature storage and low-temperature discharge performance.
Innovation Solution
Incorporating a lithium-containing transition metal composite oxide LixNazCo1-yMyO2 in the positive electrode and a specific non-aqueous electrolyte with compounds of Formulas I, II, and III, along with other additives, to form protective layers that enhance interface stability and ion transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional electrolyte formulations are used to improve high-temperature performance, then high-temperature storage performance is improved, but low-temperature discharge performance deteriorates
Solution Approach 1:
The electrolyte is segmented into multiple functional components: a base electrolyte (cyclic carbonate + chain carbonate) for general ion transport, a fluorinated additive (Formula I) for high-temperature stability and protective film formation, and a nitrile additive (Formula II or III) for low-temperature performance enhancement. Each component serves a specific temperature range optimization purpose.
Solution Approach 2:
The patent optimizes specific parameter ranges: mass percentage of compound (I) is 0.01-5%, mass percentage of compound (II) is 0.1-5%, mass percentage of compound (III) is 0.1-5%, and their ratio A/(B+C) is 0.1-10. These parameter changes enable the electrolyte to achieve both high-temperature stability and low-temperature discharge performance.
2Stability of the object's composition
If the positive electrode material composition is modified to improve stability, then high-temperature storage performance is improved, but low-temperature ion transport is hindered
Solution Approach 1:
The fluorinated compound (I) and nitrile compounds (II, III) act as intermediaries between the positive electrode material layer and the electrolyte. They form protective interface films that stabilize the electrode material at high temperatures while maintaining ion transport pathways for low-temperature performance.
Solution Approach 2:
The patent uses a composite electrolyte system combining multiple compounds (fluorinated compound I + nitrile compounds II and/or III) working synergistically. The fluorinated compound provides thermal stability and film formation, while the nitrile compounds enhance low-temperature ionic conductivity, creating a composite functional system.
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 solution improves both high-temperature storage and low-temperature discharge performance by stabilizing the electrode interface and facilitating lithium-ion transport, thereby enhancing the electrochemical apparatus's overall performance.
Implementation Method 1
lone pair electrons in a sulfone functional group of the compound of Formula I can specifically bind to cobalt atoms and M atoms in the lithium-containing transition metal composite oxide LixNazCo1-yMyO2
Implementation Method 2
facilitating lithium-ion interface transport at low temperatures
Data Source
AI summary
An electrochemical apparatus includes a positive electrode and a non-aqueous electrolyte, where the positive electrode includes a positive electrode material layer disposed on at least one surface of a positive electrode current collector, the positive electrode material layer includes a lithium-containing transition metal composite oxide, and the lithium-containing transition metal composite oxide includes LixNazCo1-yMyO2, where 0.6<x<0.95, 0≤y<0.15, 0<z≤0.03, and M is at least one selected from a group consisting of Al, Mg, Ti, Mn, Fe, Ni, Zn, Cu, Nb, Cr, and Zr; and the non-aqueous electrolyte includes a compound of Formula I, a mass percentage of the compound of Formula I is A %, and 1≤A/z≤200.