Radial Ni-based Precursor with Phosphorus for Battery Crack Resistance
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Solution Overview
Problem
Lithium secondary batteries with high energy density suffer from safety issues and reduced lifespan due to cracks in primary particles during repeated charging and discharging, leading to insufficient charging and discharging efficiency and increased resistance.
Innovation Solution
A nickel (Ni)-based active material precursor for lithium secondary batteries is developed, featuring a porous core structure with radially arranged primary particles and a phosphorus content of 0.01 wt% to 2 wt%, where phosphorus is uniformly coated on the surface and between particles, enhancing the material's electrochemical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high energy density positive active materials (lithium-nickel-manganese-cobalt composite oxide, lithium-cobalt oxide) are used, then energy density is improved, but safety deteriorates and lifespan decreases due to cracks in primary particles during repeated charging and discharging
Solution Approach 1:
The positive active material is divided into primary particles that are radially arranged to form secondary particles. This segmentation allows each primary particle to independently accommodate volume changes during lithium insertion/extraction, preventing crack propagation that would otherwise occur in solidary structures, thereby maintaining safety and lifespan while preserving high energy density
Solution Approach 2:
Different regions of the particle structure are given different properties: the primary particles maintain high nickel content for energy density, while the radial arrangement and inter-particle spaces provide structural flexibility and crack resistance. This local differentiation allows simultaneous optimization of energy storage and structural stability
2Quantity of substance
If larger secondary particles are used, then capacity is improved, but charging and discharging efficiency deteriorates due to increased travel distance of lithium ions
Solution Approach 1:
Large secondary particles are segmented into multiple primary particles arranged radially. This creates multiple shorter lithium ion diffusion pathways from the surface to the core, reducing the maximum travel distance while maintaining the overall particle size and capacity. The radial arrangement ensures that no point in the secondary particle is too far from a primary particle interface, enhancing charging/discharging efficiency
Solution Approach 2:
The radial arrangement of primary particles within secondary particles creates a three-dimensional diffusion network. Instead of linear diffusion through large particles, lithium ions can access multiple primary particles from different directions, effectively reducing diffusion distance and improving rate capability while maintaining high capacity
3Ease of manufacture
If primary particles are used without radial arrangement, then manufacturing is simpler, but cracks occur during repeated charging and discharging leading to increased resistance and decreased lifespan
Solution Approach 1:
The material is segmented into radially arranged primary particles forming secondary particles. This structure allows controlled aggregation during manufacturing while maintaining the crack-resistant radial geometry. The segmentation enables simple coprecipitation methods to produce the desired structure, balancing manufacturing ease with improved lifespan and resistance stability
Solution Approach 2:
The radial arrangement of primary particles is established during the precipitation process before battery assembly. This preliminary structural organization prevents crack formation during subsequent charging/discharging cycles, eliminating the need for complex post-processing while ensuring long-term reliability and stable resistance characteristics
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 Ni-based active material precursor improves the lifespan and high-rate characteristics of lithium secondary batteries by reducing gas generation and facilitating lithium diffusion, leading to enhanced capacity retention and reduced internal resistance.
Implementation Method 1
phosphorus is uniformly coated on the surface and between particles
Implementation Method 2
facilitating lithium diffusion
Data Source
AI summary
A nickel (Ni)-based active material precursor for a lithium secondary battery, a preparing method thereof, a Ni-based active material obtained therefrom, and a lithium secondary battery including a positive electrode including the same, are provided. The Ni-based active material precursor includes 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. Phosphorus (P) may be present in the porous core portion, between the plurality of primary particles, and on the surface of the secondary particle, and the content of the phosphorus may be in a range of 0.01 wt % to 2 wt % based on a total weight of the Ni-based active material precursor.