Single-Crystal Cathode Coating for Compaction-Capacity Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Monocrystalline positive electrode materials face challenges in balancing compaction performance and capacity performance, with existing materials experiencing capacity degradation and safety hazards due to anisotropic expansion and contraction during charging and discharging.
Innovation Solution
A monocrystalline positive electrode material is developed with a particulate structure comprising first and second particles of specific diameters and a coating layer, where the coating layer thickness varies based on residual alkali content, ensuring high compaction density and capacity through co-sintering and controlled sintering temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of monocrystalline positive electrode material is increased to improve compaction performance, then compaction performance is improved, but electrochemical performance such as capacity decreases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core region and outer shell region have different coating layer thicknesses. The outer shell region has a thicker coating layer to provide protection and ion conduction, while the inner core region has a thinner coating layer to maintain electrochemical activity. This localized differentiation allows the material to achieve both high compaction density and good electrochemical performance simultaneously.
2Reliability
If a coating layer is added to improve capacity, then capacity is improved, but compaction performance deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the coating layer thickness to be within a specific range (5-100 nm) and optimizing the ratio of coating layer thickness to particle diameter. By precisely controlling these parameters, the coating layer provides sufficient capacity enhancement while minimizing the negative impact on compaction performance. The thickness parameter is optimized to balance protective function with density requirements.
3Ease of manufacture
If uniform coating layer thickness is applied to all particles, then manufacturing simplicity is maintained, but performance optimization is limited
Solution Approach 1:
The patent implements local quality through a two-region coating structure where particles are divided into inner core regions and outer shell regions with different coating thicknesses. This can be achieved by controlling the sintering process conditions, such as using a core-shell precursor structure or controlling the diffusion of coating materials during sintering, allowing different regions to receive different amounts of coating material. This approach optimizes performance while maintaining reasonable manufacturing 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 solution provides a monocrystalline positive electrode material with enhanced compaction performance and capacity density, preventing cycle performance degradation by optimizing the coating layer thickness relative to particle size.
Implementation Method 1
the coating layer includes a fast ion conductor
Implementation Method 2
The particulate matter is obtained by co-sintering a mixture containing a first inner layer material and a second inner layer material
Data Source
Figure 1
AI summary
Provided are a monocrystalline positive electrode material, a preparation method thereof and a lithium-ion battery. The monocrystalline positive electrode material is a particulate matter, including an inner layer material and a coating layer coated on the surface of the inner layer material; where the particulate matter includes first particles having an average particle diameter F1 of 1.0-2.0 µm and second particles having an average particle diameter F2 of 2.5-6.0 µm, and the average thickness T1 of the coating layer of the first particles is less than the average thickness T2 of the coating layer of the second particles; the coating layer includes a fast ion conductor, and the molecular expression of the inner layer material is: Li1+a[NixCoyMzQb]O2±cAd, where 0≤a<0.20, 0.60≤x<1.0, 0<y<0.30, 0<z<0.30, 0≤b<0.20, c≤0.02, 0≤d≤0.05, and x+y+z+b=1; M is Mn and/or Al; Q is selected from at least one of Zr, Mg, Ti, Te, Ca, Sr, Sb, Nb, Pb, V, Ge, Se, W, Mo, Zn, Ce, and Y; and A is selected from at least one of F, Cl, and S.