W-Doped High-Nickel Cathode Morphology for Capacity and Cycling Stability
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Solution Overview
Problem
High-nickel cathode materials with spherical secondary particles and single-crystal particles face challenges in stability, cycling performance, and capacity due to differences in preparation processes, leading to suboptimal performance when combined.
Innovation Solution
A W-containing high-nickel ternary cathode material with both spherical secondary particles and single-crystal particles is developed, where tungsten is doped into the spherical particles to control growth and form a lithium tungstate coating layer, allowing for one-time sintering under controlled conditions to achieve optimal morphology and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If spherical secondary particle materials are used, then capacity advantage is achieved, but high-temperature cycling performance and stability deteriorate
Solution Approach 1:
The patent creates a composite material system combining spherical secondary particles and single-crystal particles in a gradient structure. The spherical secondary particles provide high capacity while the single-crystal particles provide excellent stability and low gas production, achieving a balance between capacity and reliability through material composition rather than pure physical mixing.
Solution Approach 2:
The patent implements local quality by creating a gradient structure where different regions of the cathode material have different compositions and morphologies. The gradient design allows spherical secondary particles to dominate in regions requiring high capacity while single-crystal particles are positioned in regions requiring stability, optimizing local performance throughout the material.
2Reliability
If single-crystal materials are used, then cycling performance and gas production are improved, but capacity is reduced
Solution Approach 1:
The patent creates a composite material system combining spherical secondary particles and single-crystal particles in a gradient structure. The spherical secondary particles provide high capacity while the single-crystal particles provide excellent stability and low gas production, achieving a balance between capacity and reliability through material composition rather than pure physical mixing.
3Volume of stationary object
If physical blending of two morphology materials is used, then compacted density is increased, but capacity and cycling performance are not effectively improved
Solution Approach 1:
The patent creates a composite material system combining spherical secondary particles and single-crystal particles in a gradient structure. The spherical secondary particles provide high capacity while the single-crystal particles provide excellent stability and low gas production, achieving a balance between capacity and reliability through material composition rather than pure physical mixing.
Solution Approach 2:
The patent merges the synthesis processes by using a one-time sintering method that simultaneously forms both spherical secondary particles and single-crystal particles from a gradient precursor, rather than separately preparing and physically mixing the two materials. This integrated approach ensures compatible cell parameters and optimal performance.
4Ease of manufacture
If physical blending of materials with different preparation processes is used, then simple mixing is achieved, but cell parameter mismatch requires different battery systems
Solution Approach 1:
The patent merges the synthesis processes by using a one-time sintering method that simultaneously forms both spherical secondary particles and single-crystal particles from a gradient precursor, rather than separately preparing and physically mixing the two materials. This integrated approach ensures compatible cell parameters and optimal performance.
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 approach results in improved capacity, cycling performance, and compacted density, with the tungsten coating enhancing electrochemical performance and enabling the coexistence of both particle morphologies in a battery system, addressing the limitations of previous methods.
Implementation Method 1
W restricts the growth of primary particles and promotes the generation of secondary spheres
Implementation Method 2
the spherical secondary particles are doped with W (because a precursor is doped with W and W restricts the growth of primary particles and promotes the generation of secondary spheres, the spherical secondary particles necessarily include W)
Implementation Method 3
one-time sintering is conducted to obtain the high-nickel cathode material with both single-crystal particles and spherical secondary particles
Data Source
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AI summary
The present disclosure discloses a W-containing high-nickel ternary cathode material, including both spherical secondary particles and single-crystal particles. There is basically no W inside the single-crystal particles, and the spherical secondary particles are doped with W. A preparation method of the W-containing high-nickel ternary cathode material includes: mixing a nickel salt, a cobalt salt, and a manganese salt according to a specified molar ratio, and adding an ammonia solution and a sodium hydroxide solution for co-precipitation to prepare a precursor A; mixing a nickel salt, a cobalt salt, a manganese salt, and a tungsten salt, and adding an ammonia solution and a sodium hydroxide solution for co-precipitation to prepare a W-containing precursor B; and mixing the precursor A, the precursor B, a lithium source, and a doping element M-containing compound, and subjecting a resulting mixture to high-temperature sintering in an oxygen atmosphere to obtain the high-nickel ternary cathode material including both spherical secondary particles and single-crystal particles. While increasing the capacity, the spherical secondary particles in the product of the present disclosure can ensure that a crystal structure will not undergo obvious phase transition when lithium ions are deintercalated during a cycling process, which helps to improve the cycling performance.