Spinel Lithium Composite Oxide High-Temperature Stability
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Solution Overview
Problem
Spinel-type lithium metal composite oxides used in lithium batteries face challenges in maintaining capacity at high temperatures, particularly in electric vehicles and hybrid electric vehicles, due to instability in the crystal structure during charging and discharging.
Innovation Solution
A spinel-type lithium metal composite oxide with specific characteristics, including oxygen occupancy of 0.965 to 1.000, lattice strain of 0.015 to 0.090, and a Na/Mn molar ratio of 0.00<Na/Mn<1.00×10−2, is developed to enhance high-temperature storage characteristics by stabilizing the crystal structure and mitigating strain variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If spinel-type lithium metal composite oxide is used as positive electrode active material for lithium batteries, then power output characteristics are improved due to three-dimensional insertion and release of Li ions, but high-temperature storage characteristics deteriorate due to crystal structure instability
Solution Approach 1:
The invention controls specific crystallographic parameters including the a-axis lattice constant (8.22-8.26 Å), unit cell volume (58.01-58.22 ų), and oxygen occupancy (0.970-1.000) to simultaneously achieve excellent power output characteristics and high-temperature storage stability. By precisely adjusting these structural parameters, the material maintains capacity at both high power rates and elevated storage temperatures.
Solution Approach 2:
The invention uses a composite oxide material with the formula Li1+xM2-xO4-δ where M represents a combination of transition metals (Mn, Ni, Co, Al, Mg, Ti, Cr, Fe, Cu, or Zn). This composite approach combines the advantages of different metal elements to achieve both high power output through three-dimensional Li ion diffusion and improved structural stability at high temperatures.
2Use of energy by moving object
If lithium metal composite oxide with layered structure is used as positive electrode active material, then energy density is improved, but power output characteristics deteriorate compared to spinel structure
Solution Approach 1:
The invention adopts the spinel crystal structure which enables three-dimensional insertion and release of Li ions, contrasting with the two-dimensional diffusion pathways in layered structures. This dimensional advantage provides superior power output characteristics while the controlled structural parameters ensure adequate energy density for practical battery applications.
Data Source
AI summary
Provided is a spinel-type lithium metal composite oxide that makes it possible to achieve excellent high-temperature storage characteristics when used as a positive electrode active material of a lithium battery. The spinel-type (Fd-3m) lithium metal composite oxide is characterized by the oxygen occupancy (OCC) thereof as determined by the Rietveld method being 0.965-1.000, the lattice strain thereof as determined by the Williamson-Hall method being 0.015-0.090, and the ratio (Na/Mn) of the molar content of Na to the molar content of Mn satisfying 0.00<Na/Mn<1.00×10−2.