Cathode Active Material Crystallite Ratio for Low-Temperature Battery Output
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges in maintaining high output characteristics, especially in low-temperature environments, due to increased cathode resistance, which affects their performance and usability in portable electronics and electric vehicles.
Innovation Solution
The cathode active material for non-aqueous electrolyte secondary batteries is optimized by controlling the crystallite size ratio and particle size distribution of lithium nickel cobalt manganese composite oxide, specifically within the ranges of 0 < (crystallite size at plane (104)/crystallite size at plane (003)) < 0.60, with crystallite sizes of 40 nm to 80 nm and 80 nm to 140 nm respectively, and average particle sizes of 3 µm to 20 µm, to reduce cathode resistance and enhance low-temperature 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 and 4V class voltage are achieved, but cathode resistance increases in low-temperature environments, degrading output characteristics
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crystallite size ratio parameter (plane (104)/plane (003)) to be 0.60 or less, and controlling the c-axis crystallite size to be 100 nm or less. These parameter optimizations reduce cathode resistance in low-temperature environments while maintaining high energy density, directly resolving the technical contradiction between energy density and low-temperature performance
Solution Approach 2:
The patent uses lithium nickel cobalt manganese composite oxide (LiNi_xCo_yMn_zO2) as the cathode material, combining multiple metal elements to create a composite material that achieves both high energy density and improved low-temperature characteristics. The composite structure allows optimization of both capacity and resistance properties that cannot be achieved with single-element materials
2Reliability
If crystallite size is reduced to improve low-temperature performance, then cathode resistance decreases, but manufacturing precision requirements increase
Solution Approach 1:
The patent establishes specific parameter ranges for crystallite size (c-axis: 100 nm or less, a-axis: 200 nm or less) and their ratio (0.60 or less), providing clear manufacturing targets. These parameter specifications enable consistent production of low-temperature high-performance cathode materials while maintaining feasible manufacturing precision requirements
Solution Approach 2:
The patent applies partial action by focusing control on the most critical parameter (c-axis crystallite size and its ratio to a-axis) rather than controlling all crystal dimensions equally. By concentrating precision requirements on the c-axis dimension which has the greatest impact on low-temperature performance, the patent achieves effective resistance reduction with manageable manufacturing precision
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 approach results in a non-aqueous electrolyte secondary battery with improved high-capacity and high-output characteristics at low temperatures, facilitating their use in compact portable devices and electric vehicles while ensuring safety and cost-effectiveness.
Implementation Method 1
the ratio of the crystallite size found from the half peak width of a diffraction peak at plane (104) with respect to the crystallite size found from the half peak width of a diffraction peak at plane (003) in powder X-ray diffraction that uses CuKα rays
Data Source
Figure 1~2
AI summary
Provided is an industrial manufacturing method for producing a cathode active material for a non-aqueous electrolyte secondary battery capable of improving output characteristics in low-temperature environment use. A lithium mixture that includes composite hydroxide particles and a lithium compound is calcined in an oxidizing atmosphere under the condition of a temperature rising time from 650°C to a calcination temperature being set to 0.5 to 1.5 hours and the calcination temperature being set to 850°C to 1000°C and maintained for 1.0 to 5.0 hours. The cathode active material that is obtained is expressed by the general formula (A): Li1+sNixCoyMnzMtO2, where -0.05 ≤ s ≤ 0.20, x + y + z + t = 1,0.3 7, 0.1 < y < 0.4, 0.1 < z < 0.4, 0 ≤ t ≤ 0.05, and M is one or more types of elements selected from Ca, Mg, Al, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W. The cathode active material includes hexagonal lithium composite oxide particles having a layered structure and includes secondary particles in which primary particles are aggregated, with the ratio of the crystallite size at plane (104) with respect to the crystallite size at plane (003) being greater than 0 and less than 0.60.