Lithium Mixed Metal Oxide Composite for High Power Batteries
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries using existing electrode active materials struggle to achieve high power output at high current rates, particularly in applications like automobiles and power tools.
Innovation Solution
A mixture of two lithium mixed metal oxides with specific BET surface areas and particle size ranges is used, where the first lithium mixed metal oxide has a BET surface area of 3 to 30 m2/g and the second has a BET surface area of 0.1 to 2 m2/g, with the first oxide containing Fe and the second containing Ni or Co, to enhance the battery's rate property and discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a highly stable lithium mixed metal oxide with low specific surface area (2.4 m2/g) is used, then stability is improved, but power output at high current rate deteriorates
Solution Approach 1:
The invention uses a composite electrode active material consisting of two types of lithium mixed metal oxides with different specific surface areas. The first lithium mixed metal oxide has a specific surface area of 2.0 m2/g or less (high stability), while the second has 2.0 m2/g or more (high power output). By combining these two materials, the electrode achieves both high stability and high power output at high current rates, resolving the contradiction between stability and power.
2Power
If the specific surface area of lithium mixed metal oxide is increased to improve power output, then power output at high current rate is improved, but stability deteriorates
Solution Approach 1:
The invention creates a composite structure where two lithium mixed metal oxides with contrasting specific surface areas are combined. The first oxide (≤2.0 m2/g) provides stability, while the second oxide (≥2.0 m2/g) provides high power output capability. This composite approach allows the electrode to simultaneously achieve both high stability and high power output, eliminating the need to choose one over the other.
3Ease of manufacture
If a single type of lithium mixed metal oxide is used, then manufacturing is simplified, but both high stability and high power output cannot be achieved simultaneously
Solution Approach 1:
The invention employs a composite of two lithium mixed metal oxides that can be manufactured separately using existing processes, then mixed together. This approach maintains manufacturing simplicity while achieving superior performance. The two components are mixed in a weight ratio between 9:1 and 1:9, with both having specific surface areas of 2.0 m2/g or less, allowing the composite to deliver both high stability and high power output simultaneously.
Data Source
AI summary
The present invention provides an electrode active material, an electrode and a nonaqueous electrolyte secondary battery. The electrode active material comprises a mixture of 10 parts by weight to 900 parts by weight of a first lithium mixed metal oxide and 100 parts by weight of a second lithium mixed metal oxide, wherein the first lithium mixed metal oxide is in a powder form and has a BET specific surface area of 3 m2/g or more and 30 m2/g or less, and the second lithium mixed metal oxide is in a powder form and has a BET specific surface area of 0.1 m2/g or more and 2 m2/g or less.