High-Nickel Cathode Material Sintering for Cycle Stability
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Solution Overview
Problem
High-nickel ternary cathode materials in lithium-ion batteries suffer from structural instability due to Li/Ni mixed occupancy and lithium-nickel disordering, leading to reduced cycle performance and stability.
Innovation Solution
A cathode active material with controlled offset angle of the (104) diffraction peak and limited height change of the transition metal layer, achieved through a three-stage sintering process with specific temperature and oxygen flow conditions, along with a coating layer to enhance structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel ternary cathode materials are used to increase energy density, then specific capacity is improved, but structural stability deteriorates due to Li/Ni mixed occupancy and lithium-nickel disordering
Solution Approach 1:
The patent applies parameter changes by precisely controlling the sintering temperature (900-1100°C) and oxygen flow rate (500-1000 mL/min) during the two-stage sintering process. These parameter optimizations suppress lithium-nickel disordering and stabilize the crystal structure, enabling high-nickel ternary materials to maintain both high specific capacity and structural stability during charging and discharging cycles
Solution Approach 2:
The patent employs composite materials by creating a core-shell structure where the cathode active material particles are coated with a protective layer formed during the two-stage sintering process. This composite structure prevents direct contact between the high-nickel material and electrolyte, reducing structural degradation while maintaining high capacity, thereby resolving the contradiction between energy density and structural stability
2Quantity of substance
If high-nickel ternary cathode materials are used to increase energy density, then battery capacity is improved, but cycle performance deteriorates due to material structure instability
Solution Approach 1:
The patent applies preliminary action by performing a two-stage sintering process where the first stage (900-1100°C for 10-20 hours) pre-forms the crystal structure and reduces lithium-nickel disordering before the second stage (900-1100°C for 5-15 hours with oxygen flow) further stabilizes the structure. This preliminary structural stabilization ensures the material maintains its integrity during subsequent charging and discharging cycles, thereby improving cycle performance while maintaining high capacity
3Device complexity
If conventional sintering processes are used for simplicity, then manufacturing complexity is reduced, but manufacturing precision deteriorates in controlling particle size and structure
Solution Approach 1:
The patent applies segmentation by dividing the sintering process into two distinct stages: first sintering (900-1100°C for 10-20 hours) to form the basic crystal structure and reduce lithium-nickel disordering, and second sintering (900-1100°C for 5-15 hours with oxygen flow) to further stabilize the structure and control particle morphology. This segmented approach enables precise control over particle size (5-20 μm) and crystal structure without requiring overly complex equipment, achieving manufacturing precision through process division rather than equipment complexity
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 cathode active material exhibits improved structural stability and extended cycle life, maintaining performance in repeated charging and discharging processes.
Implementation Method 1
a three-stage sintering process with specific temperature and oxygen flow conditions
Implementation Method 2
along with a coating layer to enhance structural stability
Data Source
AI summary
The present application relates to the technical field of lithium-ion battery, and particularly, to a cathode active material and a preparation method thereof, a positive electrode plate, a battery, and an electrical apparatus. An offset angle of a (104) diffraction peak of the cathode active material is αnm, n is the number of charging cycles of a battery including the cathode active material, where n is an integer; m % is a percentage of a charging capacity to a total capacity of the battery at a n-th charging cycle of the battery; αnm is a 2θ value corresponding to the (104) diffraction peak in an XRD diffraction spectrum of the cathode active material when the percentage of the charging capacity to the total capacity of the battery is m % at the n-th charging cycle of the battery; αnm satisfies: α10050−α1000≤0.250°; and α100100−α1000≤1.500°.