Li-Ion Cathode-Electrolyte Composition for Gas Suppression
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Solution Overview
Problem
Lithium-ion batteries experience gas generation due to side reactions between the electrolytic solution and positive active material, leading to swelling and safety concerns, as well as rapid capacity attenuation during charge and discharge cycles.
Innovation Solution
The electrochemical device incorporates a positive electrode with a positive active material doped with elements like Al, B, Ca, Mg, Ti, Cu, Nb, Si, Zr, or W, and an electrolytic solution containing compounds such as 1,3-propane sultone, LiPO2F2, and additives like lithium tetrafluoroborate, which form a stable solid electrolyte interface (SEI) film to reduce side reactions and improve structural stability, thereby mitigating gas generation and enhancing cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytic solutions are used, then the electrochemical device can operate, but gas generation occurs due to side reactions between the electrolytic solution and positive active material, leading to swelling and safety concerns
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate compound as an intermediary substance in the electrolytic solution. This compound acts as a mediator that facilitates the formation of a stable solid electrolyte interface (SEI) film on the positive electrode, which then serves as a protective barrier preventing direct contact and harmful side reactions between the electrolytic solution and positive active material, thereby eliminating gas generation while maintaining device operation
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolytic solution by incorporating fluorinated cyclic carbonate compounds with specific molecular structures (Formula I) and ratios (0.1-5% by mass). This parameter change transforms the electrolytic solution's interaction characteristics with the positive active material, enabling the formation of a stable SEI film that prevents gas-generating side reactions while maintaining ionic conductivity
2Productivity
If conventional electrolytic solutions are used, then the electrochemical device can charge and discharge, but rapid capacity attenuation occurs during charge and discharge cycles
Solution Approach 1:
The patent applies preliminary action by having the fluorinated cyclic carbonate compound react first during initial charging cycles to form a stable solid electrolyte interface (SEI) film on the positive electrode before normal operation begins. This pre-formed protective film prevents subsequent degradation reactions, thereby maintaining capacity and extending cycle life without compromising charge and discharge performance
3Object-generated harmful factors
If the electrolytic solution composition is modified to reduce side reactions, then gas generation is reduced, but the complexity of the electrolytic solution formulation increases
Solution Approach 1:
The patent applies local quality by introducing the fluorinated cyclic carbonate compound specifically at the positive electrode interface rather than uniformly throughout the entire battery system. The compound concentrates at the positive electrode surface where it forms a localized protective SEI film, achieving gas reduction with minimal addition (0.1-5% by mass) and without requiring systematic reformulation of the entire electrolytic solution composition
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 effectively reduces gas generation and improves the cycle stability and safety of the electrochemical device by forming a protective SEI film, maintaining excellent electrochemical performance and extending the battery's service life.
Implementation Method 1
compounds such as 1,3-propane sultone, LiPO2F2, and additives like lithium tetrafluoroborate, which form a stable solid electrolyte interface (SEI) film to reduce side reactions
Implementation Method 2
The positive active material includes an element A. The element A is at least one selected from the group consisting of Al, B, Ca, Mg, Ti, Cu, Nb, Si, Zr, or W
Data Source
AI summary
An electrochemical device includes a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, and an electrolytic solution. The positive electrode includes a positive current collector and a positive active material layer disposed on the positive current collector. The positive active material layer includes a positive active material. The positive active material includes an element A. The element A is selected from at least one of Al, B, Ca, Mg, Ti, Cu, Nb, Si, Zr, Y, or W. The electrolytic solution includes at least one of 1,3-propane sultone or a derivative thereof. A mass ratio of the element A in the positive active material to 1,3-propane sultone or a derivative is 1:0.2 to 1:50.