Silicate Ester Electrolyte for High-Nickel Battery Interface Stability
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Solution Overview
Problem
High-nickel positive electrode materials in lithium-ion secondary batteries suffer from structural changes, microcracks, and interface instability, leading to rapid capacity decay and increased impedance due to oxidizability and interaction with HF acid in the electrolyte, resulting in poor cycling stability.
Innovation Solution
Incorporating a silicate ester or its derivative with specific cyclic or non-cyclic structures into the electrolyte as a solvent, co-solvent, or additive, which generates stable silicon salts like lithium silicate that enhance interface stability and suppress electrolyte decomposition, thereby improving the battery's cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-nickel positive electrode materials are used to increase capacity, then energy density is improved, but interface stability deteriorates due to increased oxidizability and structural changes
Solution Approach 1:
The silicate ester acts as an intermediary substance between the high-nickel positive electrode material and the electrolyte. It forms a protective interface layer that mediates the interaction, preventing direct contact between the oxidizable electrode surface and the electrolyte, thus maintaining interface stability while enabling high energy density operation
Solution Approach 2:
The invention changes the chemical composition parameter of the electrolyte by introducing silicate ester with specific molecular structures (cyclic or non-cyclic). This parameter change modifies the interface chemistry, creating a stable solid electrolyte interface (SEI) that prevents degradation of high-nickel materials, thereby enabling the use of high-energy-density materials without suffering from their inherent instability
2Use of energy by moving object
If high-nickel positive electrode materials are used to increase capacity, then energy density is improved, but cycling stability deteriorates due to microcracks and structural changes
Solution Approach 1:
The silicate ester provides beforehand cushioning by forming a pre-protective interface layer on the positive electrode material before cycling begins. This protective layer cushions the electrode material against structural changes and microcrack formation during subsequent charge-discharge cycles, thereby maintaining cycling stability while utilizing high-nickel materials for high energy density
Solution Approach 2:
The invention creates a composite interface system consisting of the silicate ester-modified electrolyte and the high-nickel positive electrode material. This composite approach combines the high capacity benefits of nickel-rich materials with the protective properties of silicate ester, resulting in a stable interface that maintains cycling performance over extended periods
3Reliability
If LiPF6-based electrolyte with HF acid is used to ensure conductivity, then ionic conductivity is improved, but positive electrode material stability deteriorates due to HF acid attack and transition metal ion dissolution
Solution Approach 1:
The silicate ester converts the harmful effect of HF acid into a beneficial protective mechanism. Instead of allowing HF acid to directly attack and dissolve the positive electrode material, the silicate ester reacts with HF acid to form a stable protective layer, thereby neutralizing the harmful effect while maintaining the ionic conductivity benefits of LiPF6-based electrolyte
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 introduction of silicate esters with specific structures significantly improves interface stability, maintaining satisfactory cycling stability and capacity retention rates after multiple charge and discharge cycles, reducing impedance and enhancing the overall kinetic performance of the battery.
Implementation Method 1
the silicate ester and/or the derivative thereof may be contained in the electrolyte of the secondary battery and may be used as a solvent, co-solvent, and/or additive in the electrolyte... generates stable silicon salts like lithium silicate that enhance interface stability and suppress electrolyte decomposition
Data Source
AI summary
This application relates to a secondary battery including a silicate ester and/or a derivative thereof, where the silicate ester and/or the derivative thereof includes astructure in a cyclic or non-cyclic structure or astructure in a cyclic structure. This application further relates to a battery pack including the secondary battery and an electric apparatus including the secondary battery or the battery pack.