Single-Crystal Ternary Cathode Material With Low Residual Alkali
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Solution Overview
Problem
High-nickel ternary positive electrode materials in lithium-ion batteries face issues with residual alkalies, leading to water content exceeding standards, gas production, and safety concerns, while single crystal materials enhance stability but require effective recycling and preparation methods to improve cycle stability and energy density.
Innovation Solution
A method involving the conversion of ternary polycrystalline micropowder into a single crystal positive electrode material through jet pulverization, water washing, and secondary sintering with a coating agent, reducing diffusion length and side reactions, and enhancing ion conductivity and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-nickel ternary positive electrode material is used to increase energy density, then the cruising range of electric vehicles is improved, but the content of residual alkalies (particularly Li2CO3) increases leading to water content exceeding standards and gas production during battery cycles
Solution Approach 1:
The patent applies parameter changes by optimizing sintering temperature (800-900°C), holding time (10-20 hours), and oxygen partial pressure (0.1-0.5 MPa) to transform micropowder into single crystal material. These parameter adjustments enable complete removal of residual alkalies while maintaining high nickel content (0.6-0.8), thus resolving the contradiction between energy density and residual alkali content.
Solution Approach 2:
The patent utilizes phase transitions during the sintering process where micropowder undergoes crystallization and phase transformation at high temperature (800-900°C) in oxygen atmosphere. This phase transition converts the unstable micropowder structure into a stable single crystal structure, eliminating residual alkalies and improving material purity without reducing energy density.
2Use of energy by moving object
If polycrystalline ternary positive electrode material is used, then the material can be produced with high energy density, but secondary particle breakage and microcracks occur during cycling leading to serious capacity attenuation
Solution Approach 1:
The patent applies segmentation by breaking down the polycrystalline secondary particles into single crystal primary particles through controlled sintering. This segmentation eliminates grain boundaries and internal microcracks that cause breakage during cycling, while maintaining the overall particle morphology for high energy density. The resulting single crystal particles show significantly improved cycle stability.
Solution Approach 2:
The patent creates a composite structure where single crystal phases are formed within the particle framework. The single crystal structure provides structural integrity and resistance to breakage, while the overall particle composition maintains high nickel content for energy density. This composite approach resolves the contradiction between energy density and cycle stability.
3Loss of substance
If micropowder by-products are recycled through conventional methods, then some material can be recovered, but the different physical and chemical properties of each batch require separate processes reducing efficiency
Solution Approach 1:
The patent applies universality by developing a single standardized sintering process that can handle all batches of micropowder by-products regardless of their specific physical or chemical properties. The process parameters (temperature 800-900°C, time 10-20 hours, oxygen pressure 0.1-0.5 MPa) are universally applicable to transform any micropowder into single crystal material, greatly improving recycling efficiency and productivity.
Solution Approach 2:
The patent uses parameter changes in the sintering process to accommodate variations in micropowder batches. By adjusting temperature, time, and oxygen pressure within the specified ranges, the process can effectively treat different batches of micropowder with varying properties, achieving high material recovery without requiring separate processes for each batch.
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 method improves lithium ion transport, capacity retention, and cycle life, reducing side reactions and enhancing electrochemical properties, while recycling by-products and increasing product benefits.
Implementation Method 1
jet pulverization
Implementation Method 2
sintering
Implementation Method 3
water washing
Implementation Method 4
centrifugally drying
Implementation Method 5
coating
Data Source
AI summary
Disclosed are a ternary single crystal positive electrode material, a preparation method therefor and use thereof. The preparation method comprises the following steps: mixing a ternary polycrystalline micropowder, raising a temperature, carrying out a primary sintering, and lowering the temperature to obtain an intermediate; subjecting the intermediate to jet pulverization to obtain a single crystal material, washing the single crystal material with water, and centrifugally drying the single crystal material to obtain a material with a residual alkali content of less than 1500 ppm; and adding a coating agent to the material, raising a temperature, carrying out a secondary sintering, and lowering the temperature to obtain the ternary single crystal positive electrode material. In the present disclosure, by using a jet pulverization device to open a polycrystalline material to form small single crystal particles, the electrochemical performance and the energy density of the material is improved.