Nickel-Based Cathode Precursor Radial Particle Alignment
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Solution Overview
Problem
Lithium secondary batteries with high energy density suffer from poor safety, reduced lifetime, and inefficient charging and discharging due to the movement distance of lithium ions and cracking of primary particles during repeated charging and discharging.
Innovation Solution
A nickel-based active material precursor for lithium secondary batteries is developed, featuring secondary particles with a porous core and radially arranged primary particles, where 50% or more of the primary particles' major axes are aligned along the normal direction of the surface, reducing lithium ion diffusion distance and accommodating volume changes during charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high energy density cathode materials are used, then energy density is improved, but safety and lifetime are worsened
Solution Approach 1:
The cathode active material is divided into multiple primary particles (0.5-5 μm) that aggregate to form secondary particles (5-20 μm). This segmentation reduces the diffusion distance for lithium ions within each primary particle, improving charge-discharge efficiency while maintaining high energy density. The multi-particle structure also prevents crack propagation, enhancing safety and lifetime.
Solution Approach 2:
The invention creates a non-uniform particle size distribution within secondary particles, with primary particles having different sizes (0.5-5 μm). This local quality variation optimizes lithium ion diffusion paths and accommodates volume changes during charging-discharging cycles, improving both performance and reliability simultaneously.
2Quantity of substance
If large secondary particle size is used, then capacity is improved, but charge-discharge efficiency is worsened
Solution Approach 1:
Large secondary particles (5-20 μm) providing high capacity are segmented into smaller primary particles (0.5-5 μm). This segmentation ensures that while the overall particle size maintains high capacity, the internal diffusion paths remain short, achieving both high capacity and high charge-discharge efficiency.
Solution Approach 2:
The invention transitions from a single-particle structure to a hierarchical multi-scale structure, adding dimensional complexity. Primary particles (0.5-5 μm) aggregate into secondary particles (5-20 μm), creating a multi-dimensional architecture that simultaneously optimizes capacity (outer dimension) and diffusion efficiency (inner dimension).
3Duration of action of moving object
If primary particles undergo repeated charging and discharging, then battery operation is maintained, but cracks occur and lifetime is reduced
Solution Approach 1:
The cathode material is segmented into multiple primary particles within each secondary particle. During charging-discharging cycles, volume changes are distributed across these segmented units rather than concentrating stress in a single particle, preventing crack formation and maintaining structural integrity over thousands of cycles.
Solution Approach 2:
The multi-primary-particle structure acts as a pre-designed cushioning system that absorbs and distributes mechanical stress from volume changes during lithiation-delithiation. This beforehand structural design prevents crack initiation and propagation, extending battery lifetime.
Data Source
AI summary
Provided is a nickel-based active material precursor for a lithium secondary battery, including: a secondary particle including a plurality of particulate structures, wherein each of the particulate structures includes a porous core portion and a shell portion including primary particles radially arranged on the porous core portion, and in 50% or more of the primary particles constituting a surface of the secondary particle, a major axis of each of the primary particles is aligned along a normal direction of the surface of the secondary particle. When the nickel-based active material precursor for a lithium secondary battery is used, it is possible to obtain a nickel-based active material which intercalates and deintercalates lithium and has a short diffusion distance of lithium ions.