Nonaqueous Lithium Metal Battery Cathode for Oxygen Release Control
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face safety issues due to internal pressure increases caused by oxygen generation and reaction with lithium metal during high-temperature events, such as internal short circuits, leading to potential battery damage.
Innovation Solution
Incorporating a composite oxide with Ni and at least one of Fe, V, or Nb, having a layered rock-salt crystal structure, and using an oxalate salt in the non-aqueous electrolyte to slow down oxygen release and promote uniform lithium deposition, reducing the reaction rate between oxygen and lithium metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a composite oxide containing lithium and transition metal is used as positive electrode active material to achieve higher battery capacity, then the battery capacity is improved, but oxygen is generated from the positive electrode at high temperatures which reacts with lithium metal on the negative electrode causing heat generation and internal pressure rise
Solution Approach 1:
The patent changes the chemical composition parameters of the positive electrode active material by incorporating specific transition metals (Ni, Fe, V, Ti, or Nb) in controlled ratios. This compositional modification alters the thermal decomposition behavior of the composite oxide, reducing oxygen generation at high temperatures while maintaining battery capacity
Solution Approach 2:
The patent uses a composite oxide material combining lithium with multiple transition metals (Ni, Fe, V, Ti, or Nb) to create a positive electrode active material that exhibits improved thermal stability. The composite structure allows synergistic effects where the combination of metals reduces oxygen release compared to single-metal oxides, thereby mitigating heat generation and pressure rise
2Quantity of substance
If lithium metal deposits on the negative electrode current collector during charge to achieve high capacity, then the battery capacity is improved, but the lithium metal reacts with oxygen from the positive electrode causing safety issues
Solution Approach 1:
The patent modifies the chemical composition of the positive electrode active material to reduce oxygen generation, which indirectly protects the lithium metal on the negative electrode from oxidation. By changing the transition metal composition and ratios in the composite oxide, the system reduces the availability of oxygen that would otherwise react with lithium metal, thereby improving safety while maintaining capacity
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
This configuration significantly suppresses heat generation and internal pressure rises, enhancing battery safety by reducing oxygen generation and oxidative decomposition of the electrolyte.
Implementation Method 1
When a non-aqueous electrolyte secondary battery is exposed to high temperatures due to an internal short circuit or other causes, oxygen is generated from the positive electrode containing a composite oxide
Implementation Method 2
lithium metal deposits on the negative electrode during charge, and the lithium metal dissolves from the negative electrode into the non-aqueous electrolyte during discharge
Implementation Method 3
the composite oxide contains Ni and at least one selected from the group consisting of Fe, V, Ti, and Nb, and has a structure based on a crystal structure belonging to a space group R-3m
Implementation Method 4
the non-aqueous electrolyte is oxidatively decomposed by the oxygen generated from the positive electrode, and due to the gas generation accompanying therewith, the battery internal pressure rises
Data Source
AI summary
A non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a non-aqueous electrolyte, in which lithium metal deposits on the negative electrode during charge, and the lithium metal dissolves from the negative electrode into the non-aqueous electrolyte during discharge. The positive electrode includes a positive electrode active material, the positive electrode active material includes a composite oxide containing lithium and a transition metal, and the non-aqueous electrolyte contains an oxalate salt. The composite oxide contains Ni and at least one selected from the group consisting of Fe, V, Ti, and Nb, and has a structure based on a crystal structure belonging to a space group R-3m.