Urea-Based Li-Ion Electrolyte Additive for High-Voltage NCM Stability
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Solution Overview
Problem
Conventional lithium-ion battery electrolytes based on lithium hexafluorophosphate in carbonates suffer from low oxidative stability, leading to decomposition and degradation of the cathode material at voltages above 4.4 V, resulting in low cycle stability and battery life.
Innovation Solution
Incorporating a urea-based electrolyte additive, specifically (1H-imidazol-1-yl) (morpholino)methanone (MUI), into the electrolyte of lithium-ion batteries, which enhances the electrochemical stability and forms a cathode passivation layer, thereby inhibiting metal release and oxidative decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes based on lithium hexafluorophosphate in carbonates are used, then the battery can operate, but the oxidative stability is low leading to decomposition at voltages above 4.4 V
Solution Approach 1:
A urea-based compound is introduced as an intermediary substance between the electrolyte and the cathode material. This compound forms a protective interface layer that mediates the interaction, preventing direct contact and harmful oxidation reactions between the conventional electrolyte and the cathode at high voltages above 4.4 V, thereby eliminating decomposition while maintaining battery operation.
Solution Approach 2:
The invention changes the chemical composition parameter of the electrolyte system by adding a urea-based compound with specific molecular structure and properties. This parameter change transforms the electrolyte's oxidative stability from low to high, enabling stable operation at voltages above 4.4 V without decomposition, while maintaining the beneficial properties of conventional electrolytes.
2Power
If the battery operates at high voltage above 4.4 V, then higher energy density is achieved, but cycle stability and battery life decrease due to decomposition
Solution Approach 1:
The urea-based compound acts as a protective intermediary that enables the battery to operate at high voltages above 4.4 V necessary for high energy density, while simultaneously protecting the cathode material from decomposition. This mediator allows sustained operation over many cycles by preventing the harmful reactions that would otherwise limit battery life.
Solution Approach 2:
By changing the electrolyte composition to include the urea-based compound, the battery can maintain stable performance at high operating voltages. This parameter change resolves the trade-off between power (energy density) and duration (cycle stability), allowing both to be optimized simultaneously.
3Device complexity
If no protective layer is formed on the cathode, then the electrolyte remains simple, but metal release and oxidative decomposition occur
Solution Approach 1:
The urea-based compound serves as a protective intermediary that forms an interface layer on the cathode surface. This layer acts as a barrier that prevents metal release and oxidative decomposition without significantly complicating the overall battery structure, maintaining relative simplicity while eliminating harmful effects.
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 MUI in the electrolyte significantly improves the cycle stability and service life of lithium-ion batteries, suppresses cathode material degradation, and reduces self-discharge, while maintaining effectiveness across a wide temperature range.
Implementation Method 1
forms a cathode passivation layer, thereby inhibiting metal release and oxidative decomposition
Implementation Method 2
decomposition of the electrolyte and the degradation of the cathode material occurs at 4.4 V
Implementation Method 3
decomposition of the electrolyte and the degradation of the cathode material occurs at 4.4 V
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
The present invention relates to a lithium battery comprising an anode comprising an active anode material, a cathode comprising an active cathode material comprising lithium nickel cobalt manganese oxide (NCM), and an electrolyte separating anode and cathode, wherein the electrolyte comprises a solvent or solvent mixture and lithium hexafluorophosphate, wherein the electrolyte further comprises a urea-based electrolyte additive. Moreover, the present invention further relates to the use of a specific urea- based electrolyte additive in a lithium battery for enhancing one characteristic selected from the group consisting of reversible capacity, Coulombic efficiency, cyclic stability and combinations thereof.