Cavity-Structured Cathode Particles for High-Nickel Cycle Stability
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Solution Overview
Problem
High-nickel ternary positive electrode materials in lithium-ion batteries suffer from microscopic stress during charge and discharge, leading to secondary particle rupture and deterioration of cycle and gas production performance.
Innovation Solution
A positive electrode material with a cavity structure inside secondary particles, formed by introducing an appropriate proportion of element A during precursor synthesis, which buffers volume strain and alleviates particle rupture, improving cycle life and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If element doping and coating optimization are used to modify ternary positive electrode materials, then cycle performance is improved to a certain extent, but the preparation process becomes more complicated and cumbersome
Solution Approach 1:
The patent introduces a porous coating layer containing cavities on the surface of the positive electrode material particles. This porous structure provides buffering space for volume expansion and contraction during lithium insertion and extraction, effectively reducing internal stress and improving cycle performance without requiring complex doping processes.
Solution Approach 2:
The patent creates a composite structure where the positive electrode material particles are coated with a porous layer containing cavities. This composite design combines the high capacity of ternary materials with the mechanical stability provided by the porous coating, achieving improved cycle life through a relatively simple preparation process.
2Quantity of substance
If high-nickel ternary positive electrode material is used to increase energy density, then battery capacity is improved, but the material is readily ruptured due to microscopic stress during charge and discharge
Solution Approach 1:
The patent applies beforehand cushioning by introducing a porous coating layer with cavities before the electrode material undergoes repeated charge-discharge cycles. These pre-formed cavities act as cushioning spaces that absorb and buffer the microscopic stress and volume changes occurring during lithium insertion and extraction, preventing particle rupture and maintaining structural integrity.
Solution Approach 2:
The porous coating layer with cavities provides a network of void spaces that can accommodate volume expansion and contraction of the high-nickel ternary material during electrochemical cycling. This porous structure reduces mechanical stress concentration and prevents particle cracking, thereby maintaining particle integrity while preserving high capacity.
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 cavity structure within the positive electrode material effectively releases stress, enhancing cycle life and maintaining high cycle capacity retention and reducing gas production growth, thereby improving battery performance.
Implementation Method 1
the positive electrode material may buffer the volume strain during the charge and discharge process through the internal cavity structure
Implementation Method 2
at least one element of the A element is attached to an inner layer of the cavity structure
Data Source
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AI summary
The invention provides a positive electrode material, a preparation method thereof, and an electrochemical device. The positive electrode material is a secondary particle (1) formed by the aggregation of primary particles. The secondary particle contains a cavity structure (2) inside. Based on the positive correlation characteristics between the content of an A element in the positive electrode material particles and the cavity ratio, by introducing an appropriate proportion of the A element when the positive electrode material precursor is formed, the accompanying cavity structure formed inside the precursor is at an appropriate cavity ratio, in order to ensure that the positive electrode material may buffer the volume strain during the charge and discharge process through the internal appropriate proportion of the cavity structure, and alleviate the rupture phenomenon of the secondary particle during the cycle, thereby improving the cycle life and volume energy density of the positive battery.