Lithium Metal Battery Cathode Additive for Oxygen Pressure Control
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face safety issues due to oxygen generation and pressure increase during high temperature events, such as internal short circuits, which can lead to battery case damage.
Innovation Solution
Incorporating a positive electrode additive with a particulate base material and an organic compound group bonded via a X—O-A covalent bond, where X is Si or Ti, and the organic compound group has 2 or more carbon atoms, to absorb and consume oxygen generated from the positive electrode, thereby suppressing oxygen reactions and pressure increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is deposited on the negative electrode during charging, then high capacity is achieved, but oxygen generated from the positive electrode reacts with lithium metal causing heat generation and safety issues
Solution Approach 1:
An additive comprising particulate base material with organic compound groups is introduced as an intermediary substance between the positive and negative electrodes. This additive preferentially reacts with oxygen generated from the positive electrode, preventing direct contact and harmful reactions between oxygen and lithium metal on the negative electrode, thus resolving the safety issue while maintaining high capacity operation
Solution Approach 2:
The harmful oxygen generated from the positive electrode during high temperature events is converted into a beneficial effect by having it react with the additive instead of lithium metal. The organic compound groups on the additive serve as sacrificial reactants that consume oxygen, transforming a dangerous byproduct into a controlled reaction that enhances battery safety
2Quantity of substance
If oxygen is generated from the positive electrode during high temperature events, then the battery can operate at high capacity, but internal pressure increases due to oxygen generation and nonaqueous electrolyte decomposition
Solution Approach 1:
The additive acts as an intermediary oxygen consumer that prevents oxygen from decomposing the nonaqueous electrolyte. By providing an alternative reaction pathway where oxygen reacts with the organic compound groups on the additive, the harmful decomposition of electrolyte is avoided, thereby preventing excessive internal pressure buildup while maintaining high capacity operation
Solution Approach 2:
The additive is pre-installed in the positive electrode to provide beforehand cushioning against oxygen generation. When oxygen is generated during high temperature events, the additive is already in position to react with and consume the oxygen, cushioning the system against the harmful effects of pressure increase from both oxygen generation and electrolyte decomposition
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 additive effectively suppresses oxygen generation and oxidative decomposition, reducing internal pressure and enhancing battery safety by stabilizing the reaction with lithium metal on the negative electrode.
Implementation Method 1
the additive effectively suppresses oxygen generation and oxidative decomposition
Implementation Method 2
the nonaqueous electrolyte may be oxidized and decomposed by oxygen generated from the positive electrode
Implementation Method 3
an organic compound group fixed to a surface of the base material by a covalent bond
Data Source
AI summary
A nonaqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte, wherein lithium metal deposits on the negative electrode during charging, and the lithium metal dissolves in the nonaqueous electrolyte from the negative electrode during discharging. The positive electrode includes a positive electrode mixture comprising a positive electrode active material and an additive. The positive electrode active material includes a composite oxide including lithium and a transition metal. The additive includes a particulate base material, and an organic compound group fixed to a surface of the base material by a covalent bond. The covalent bond includes a X—O-A bond. The element X is bonded to the organic compound group, and is at least one selected from the group consisting of Si and Ti. The element A is an element constituting the base material. The organic compound group has 2 or more carbon atoms.