Epoxide Electrolyte Additives for Stable High-Nickel Li-Ion Cathodes
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Solution Overview
Problem
Current Li-ion batteries face challenges with cathode stability at high voltages and temperatures, leading to capacity loss and increased interfacial resistance, particularly in high nickel content cathode materials, which are exacerbated by the breakdown of the Solid Electrolyte Interface (SEI) and Cathode Electrolyte Interface (CEI) at elevated temperatures.
Innovation Solution
The introduction of epoxide functionalized organic compounds as additives in the electrolyte, which form a stable Cathode Electrolyte Interface (CEI) and suppress oxidative decomposition, improving high-temperature performance and cycle life without excessive passivation, and incorporating a phosphorus-oxygen bond for coordination with high nickel cathode materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high voltage cathode materials are used to increase energy density, then capacity and energy density are improved, but cathode stability deteriorates due to increased oxidation and electrochemical decomposition
Solution Approach 1:
The patent introduces a mediator substance (additive with phosphorus-oxygen bond and epoxide group) that interacts with the cathode material to form a protective interface layer. This intermediary layer prevents direct contact between the electrolyte and cathode, suppressing oxidative decomposition and electrochemical oxidation while allowing lithium ion transport, thus resolving the contradiction between high energy density and cathode stability
Solution Approach 2:
The patent employs a composite additive structure containing both phosphorus-oxygen bonds and epoxide groups, combining the benefits of phosphorus-based compounds (which form stable protective films) and epoxide compounds (which provide additional stability at high potentials). This composite approach creates a synergistic effect that enhances cathode stability while maintaining high voltage performance
2Speed
If traditional carbonate-based electrolytes are used, then lithium ion transport is enabled, but SEI and CEI layers become unstable at high temperatures leading to capacity loss
Solution Approach 1:
The patent modifies the electrolyte composition by incorporating additives with specific molecular structures (phosphorus-oxygen bonds and epoxide groups) that change the chemical properties of the electrolyte system. These parameter changes enable the formation of temperature-stable SEI and CEI layers that maintain their integrity at elevated temperatures while still allowing efficient lithium ion transport
Solution Approach 2:
The patent applies local quality modification by creating distinct interface layers (SEI and CEI) with different properties from the bulk electrolyte. The additive concentrates at the electrode-electrolyte interface to form a localized protective layer with enhanced thermal stability, while the bulk electrolyte maintains its lithium ion conductivity
3Quantity of substance
If high nickel content cathode materials are used to increase capacity, then energy storage capability is improved, but interfacial resistance increases due to structural breakdown
Solution Approach 1:
The patent introduces an intermediary protective layer formed by the phosphorus-oxygen containing additive that acts as a buffer between the high nickel cathode material and the electrolyte. This intermediary layer prevents direct interaction that would cause structural breakdown, thereby maintaining low interfacial resistance while enabling high capacity operation
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 use of epoxide functionalized organic compounds enhances the stability and safety of high-voltage, high-energy Li-ion batteries by forming a protective polyether film on the cathode, reducing capacity loss and internal resistance, and maintaining stability at both room and elevated temperatures.
Implementation Method 1
additives that stabilize the cathode by polymerizing to form a CEI
Implementation Method 2
incorporating a phosphorus-oxygen bond for coordination with high nickel cathode materials
Implementation Method 3
suppress oxidative decomposition, improving high-temperature performance
Implementation Method 4
The shuttling of positive and negative ions between the battery electrodes is the main function of the electrolyte
Data Source
AI summary
Epoxide functionalized organic compounds and an electrolyte containing the epoxide functionalized organic compound additive suitable for use in electrochemical energy storage devices useful for reducing battery resistance, increasing cycle life, and improving high-temperature performance are disclosed.