Cathode Active Material Crystallinity for Low-Temperature Battery Output
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Solution Overview
Problem
Current lithium-ion secondary batteries face challenges in maintaining high output characteristics, particularly in low-temperature environments, and existing technologies struggle to adapt effectively for use in severe conditions such as cold regions and electric vehicles.
Innovation Solution
A cathode active material expressed by the formula Li1+aNixCoyMnzMtO2, where specific ratios of integrated diffraction peak widths and peak intensities are controlled, along with a manufacturing method involving a mixing process and calcination in an oxidizing atmosphere, to enhance crystallinity and output performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional lithium composite oxide cathode materials are used, then high energy density can be achieved, but output characteristics in low-temperature environments deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ratio of integrated widths of diffraction peaks (W104/W003) to be 1.38 or greater, and controlling the full width at half maximum (FWHM) of the (003) peak to be 0.35° or less. These parameter adjustments optimize the crystal structure to enable high output characteristics at low temperatures while maintaining high energy density, resolving the contradiction between energy density and low-temperature power output.
2Reliability
If cycling characteristics are improved by regulating diffraction peak intensity ratios, then battery durability increases, but output characteristics in severe environments worsen
Solution Approach 1:
The patent simultaneously optimizes multiple parameters: the integrated width ratio W104/W003 is controlled to be 1.38 or greater, and the FWHM of the (003) peak is controlled to be 0.35° or less. This multi-parameter optimization achieves both improved cycling characteristics and enhanced low-temperature output characteristics, resolving the contradiction between reliability and adaptability to severe environments.
3Power
If crystal growth is controlled to improve output characteristics, then manufacturing precision requirements increase
Solution Approach 1:
The patent replaces complex mechanical crystal growth control with a chemical approach by controlling the calcination atmosphere composition and parameters. By regulating the oxidizing atmosphere during calcination, the desired crystal structure (with W104/W003 ≥ 1.38 and FWHM003 ≤ 0.35°) is achieved more easily, reducing manufacturing precision requirements while maintaining high output characteristics.
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 solution results in a non-aqueous electrolyte secondary battery with improved high-capacity and high-output characteristics at low temperatures, suitable for portable devices and electric vehicles, while also simplifying manufacturing and enhancing safety.
Implementation Method 1
a manufacturing method involving a mixing process and calcination in an oxidizing atmosphere, to enhance crystallinity and output performance
Implementation Method 2
calcination in an oxidizing atmosphere
Implementation Method 3
the ratio of the integrated width of the diffraction peak on plane (104) with respect to the integrated width of the diffraction peak on plane (003) of the Miller indices (hkl) in powder X-ray diffraction
Implementation Method 4
powder X-ray diffraction that uses CuKα rays
Data Source
AI summary
A cathode active material for a non-aqueous electrolyte secondary battery has improved output characteristics in low-temperature environment use. A lithium mixture includes composite hydroxide particles and a lithium compound calcined in an oxidizing atmosphere under a temperature rising time from 650° C. to a calcination temperature set to 0.5-1.5 hours and the calcination temperature set to 850° C.-1000° C. and maintained for 1.0-5.0 hours. The material has the general formula (A): Li1+SNixCoyMnzM1O2 , where −0.05≤s≤0.20, x+y+z+t=1, 0.3≤x≤0.7, 0.1≤y≤0.4, 0.1≤z≤0.4, 0≤t≤0.05, and M is selected from Ca, Mg, Al, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W. The material includes hexagonal lithium composite oxide particles. The ratio of the crystallite size at plane (104) to plane (003) is greater than 0 and less than 0.60.