NCM Positive Electrode Material with Low c/a Ratio for Stable Cycling
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Solution Overview
Problem
Positive electrodes based on lithium nickel composite oxides tend to have low thermal stability and cycling performance when an added element substitutes for nickel, leading to heat generation and oxygen release during charging or discharging.
Innovation Solution
A nickel-cobalt-manganese-based active material with a specific crystal structure ratio (c/a ≤ 4.9625) and particle size, combined with controlled calcination processes, to enhance thermal stability and cycling performance, while maintaining a low weight decrease in thermal mass spectrometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If an added element substitutes for nickel in lithium nickel composite oxide to improve thermal stability, then thermal stability is improved, but cycling performance deteriorates
Solution Approach 1:
The patent changes the crystal structure parameters by controlling the c/a ratio to be 4.9625 or less through specific calcination processes. This parameter change allows achieving both improved thermal stability and maintained cycling performance without substituting nickel with added elements, thus resolving the contradiction between thermal stability and cycling performance
Solution Approach 2:
The patent creates a composite structure by forming aggregated particles with specific morphology and size (14-18 μm diameter) through controlled calcination. This composite approach achieves both thermal stability and good cycling performance without requiring element substitution
2Quantity of substance
If lithium nickel composite oxide is used in positive electrode, then high capacity is achieved, but heat generation and oxygen release occur during charging or discharging
Solution Approach 1:
The patent controls the c/a ratio parameter to be 4.9625 or less through specific calcination conditions, which changes the crystal structure to reduce thermal instability. This allows maintaining high nickel content for capacity while suppressing heat generation and oxygen release
Solution Approach 2:
The patent performs preliminary calcination treatment under controlled conditions (temperature, atmosphere, time) before battery assembly to pre-stabilize the crystal structure. This preliminary action reduces subsequent thermal decomposition and oxygen release during battery operation
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 achieves high thermal stability and improved cycling performance, with a cycle capacity retention of 93.3% or more and a weight decrease ratio per minute of 0.40% or less, effectively addressing the thermal instability issues of traditional materials.
Implementation Method 1
a ratio c/a of a length of an a-axis to a length of a c-axis in a crystal structure as obtained from an X-ray diffraction pattern analysis result is 4.9625 or less
Implementation Method 2
a weight decrease amount in thermal mass spectrometry at a temperature of 120 to 600°C and a temperature increase rate of 5°C/min is 12 mass% or less
Data Source
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AI summary
The present disclosure relates to: a positive electrode NCM (nickel-cobalt-manganese)-based active material (11) in which a ratio c/a of a length of an a-axis to a length of a c-axis in a crystal structure as obtained from an X-ray diffraction pattern analysis result is 4.9625 or less; a positive electrode (20) including the positive electrode NCM-based active material (11); and a battery (100) including the positive electrode (20). According to the present disclosure, there are provided: the positive electrode NCM-based active material (11) that can exhibit an improved cycling performance as well as high thermal stability; the positive electrode (20) including the positive electrode NCM-based active material (11); and the battery (100) including the positive electrode (20).