Polymeric Single-Crystal Cathode Material for High-Capacity Cycling
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Solution Overview
Problem
Conventional lithium-ion battery positive electrode materials face challenges in achieving high capacity per gram, good cycling performance, and good C-rate performance due to limitations in single crystal and secondary sphere materials, which result in poor structural stability and high internal resistance.
Innovation Solution
A polymeric single crystal positive electrode material is developed, formed by nesting primary particles, with a specific morphology that enhances thermal stability, reduces internal resistance, and improves cycling and C-rate performance, and is coated with an inert metal or non-metal compound to protect against electrolyte damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single crystal material is used, then cycling performance and resistance to high voltage are improved, but capacity per gram and C-rate performance deteriorate
Solution Approach 1:
The positive electrode material is divided into multiple primary particles (2-500 particles) that are nested to form a polymeric single crystal structure. This segmentation allows the material to combine the advantages of both single crystal and secondary sphere structures, achieving high capacity per gram while maintaining good cycling performance.
Solution Approach 2:
Multiple primary particles are nested within each other to form a polymeric single crystal structure. The nested configuration enables lithium ions to access multiple active particles simultaneously, improving C-rate performance while the outer shell maintains structural integrity for good cycling performance.
2Quantity of substance
If secondary sphere material is used, then capacity per gram and C-rate performance are improved, but structural stability and cycling performance deteriorate
Solution Approach 1:
The nested structure of multiple primary particles forms a polymeric single crystal where the outer shell provides structural stability and protects inner particles. This nested configuration prevents particle breakage during roll pressing while maintaining high capacity per gram.
Solution Approach 2:
The polymeric single crystal structure combines multiple primary particles into a composite structure with a unified outer shell. This composite material exhibits both the high capacity of secondary spheres and the structural stability of single crystals.
3Stability of the object's composition
If polymeric single crystal morphology is used, then thermal stability and structural stability are improved, but manufacturing complexity increases
Solution Approach 1:
The patent controls the sintering temperature (900-1100°C) and time (10-24 hours) parameters to naturally form the polymeric single crystal morphology. By optimizing these parameters, the complex nested structure forms spontaneously during sintering, reducing the need for additional manufacturing steps.
Data Source
AI summary
Disclosed are a positive electrode material and a preparation method thereof, a positive electrode plate, and a battery. The positive electrode material includes several particles having a polymeric single crystal morphology, and the particle having a polymeric single crystal morphology is formed by nesting several primary particles; and the positive electrode material meets a relational expression shown in Formula 1 as follows: D503=K×n×d503 Formula 1, where K is a coefficient having a range of 0.2≤K≤2; n is a quantity of primary particles having a range of 2≤n≤500; D50 is a median particle size of a positive electrode material, in a unit of μm; and d50 is a median particle size of a primary particle, in a unit of The positive electrode material can ensure good cycling performance, stable high voltage cycling performance and safety performance.