Cathode Active Material Surface Treatment to Reduce Battery Gas
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Solution Overview
Problem
The existing production process for positive electrode active materials in non-aqueous electrolyte secondary batteries requires washing to remove surplus lithium, which increases costs and environmental impact, and still generates significant gas during charge or storage.
Innovation Solution
A positive electrode active material is produced by calcining a mixture of a lithium compound and a transition metal oxide, followed by heat-treating the unwashed particles with a metal compound containing specific metal elements like aluminum, titanium, or tungsten, which reacts with surplus lithium to form a lithium metal compound, reducing gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If washing steps are performed to remove surplus lithium from lithium transition metal oxide particles, then gas generation during charge or storage is reduced, but production costs and environmental impact increase
Solution Approach 1:
The invention converts the harmful effect of surplus lithium (which causes gas generation) into a beneficial outcome by using it as a reactant. The surplus lithium on the particle surfaces reacts with the metal compound during heat treatment to form a stable lithium metal compound, thereby eliminating gas generation without requiring washing steps. This transforms the previously harmful surplus lithium into a useful reactant that improves battery performance.
Solution Approach 2:
The invention extracts and removes the washing, filtration, and drying steps from the production process. By eliminating these post-calcination treatment steps, the process becomes simpler, cheaper, and more environmentally friendly while still achieving the desired reduction in gas generation through the in-situ reaction of surplus lithium with the metal compound.
2Ease of manufacture
If washing steps are omitted to reduce production costs and environmental impact, then gas generation during charge or storage increases
Solution Approach 1:
The invention performs a preliminary heat treatment step after calcination but before electrode fabrication. During this heat treatment, the metal compound is added to react with surplus lithium and form a stable lithium metal compound. This preliminary action eliminates harmful lithium compounds in advance, preventing gas generation during subsequent battery charge or storage operations without requiring washing steps.
Solution Approach 2:
The metal compound acts as an intermediary substance that mediates between the surplus lithium (harmful component) and the final battery product. The metal compound reacts with surplus lithium to form a stable lithium metal compound, thereby transforming the harmful effect into a beneficial outcome and enabling the omission of washing steps.
3Manufacturing precision
If surplus lithium is present on particle surfaces to compensate for lithium loss during calcination, then manufacturing precision is improved, but gas generation during battery operation increases
Solution Approach 1:
The invention changes the chemical state of surplus lithium through heat treatment with a metal compound. The surplus lithium transforms from a harmful compound (such as lithium carbonate or lithium hydroxide) into a stable lithium metal compound. This parameter change in chemical composition and state eliminates gas generation while preserving the beneficial stoichiometric composition control achieved during calcination.
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 method eliminates the need for washing, reducing production costs and environmental impact, while significantly minimizing gas generation during charge or storage of the battery.
Implementation Method 1
a metal compound containing a metal element M and adhering to surfaces of the lithium transition metal oxide particles, and a lithium metal compound containing lithium (Li) and the metal element M and adhering to the surfaces of the lithium transition metal oxide particles
Implementation Method 2
heat-treating a mixture of the unwashed lithium transition metal oxide particles and a metal compound containing a metal element M at a temperature lower than a temperature in the calcining
Data Source
AI summary
This positive electrode active material for non-aqueous electrolyte secondary batteries comprises: lithium transition metal oxide particles; a metal compound which contains a metal element M and adheres to the surfaces of the lithium transition metal oxide particles; and a lithium metal compound which contains lithium (Li) and the metal element M and adheres to the surfaces of the lithium transition metal oxide particles. In this connection, the metal element M is composed of at least one substance that is selected from among aluminum (Al), titanium (Ti), manganese (Mn), gallium (Ga), molybdenum (Mo), tin (Sn), tungsten (W) and bismuth (Bi).