Porous Core-Shell Nickel Active Material for Lithium Batteries
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Solution Overview
Problem
Lithium secondary batteries with high energy density suffer from poor safety and reduced lifespan due to inefficient lithium ion travel distance and increased resistance caused by particle cracking during charging and discharging.
Innovation Solution
A nickel (Ni)-based active material for lithium secondary batteries is developed, featuring a porous core and shell structure with radially arranged primary particles and lithium phosphate coating, which enhances lithium ion diffusion and reduces particle stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high energy density is achieved using lithium-nickel-manganese-cobalt composite oxide, then energy density is improved, but safety deteriorates
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 compositions and functions. The core contains the high-energy-density lithium-nickel-manganese-cobalt composite oxide, while the shell provides protective functionality, allowing each region to optimize its local properties for energy storage and safety respectively
Solution Approach 2:
The patent uses composite materials by combining lithium-nickel-manganese-cobalt composite oxide with other materials in a core-shell configuration. This composite structure allows the high-energy-density material to function while being protected by the shell layer, resolving the contradiction between energy density and safety
2Quantity of substance
If particle size is increased to improve capacity, then energy storage capacity is improved, but lithium ion diffusion efficiency deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the particle into a core region and a shell region, creating a core-shell structure. This segmentation allows the particle to maintain overall large size for capacity while the shell provides optimized pathways for lithium ion diffusion, resolving the contradiction between capacity and diffusion efficiency
Solution Approach 2:
The patent applies local quality by giving different regions of the particle different structural characteristics. The core region provides capacity through its composition and volume, while the shell region provides optimized lithium ion diffusion pathways, allowing each region to fulfill its specific function
3Productivity
If repeated charging and discharging is performed to utilize battery capacity, then energy utilization is improved, but particle cracking occurs leading to decreased lifespan
Solution Approach 1:
The patent applies beforehand cushioning by providing a protective shell structure that anticipates and prevents damage from repeated charging and discharging cycles. The shell acts as a cushion that absorbs stress and prevents cracking of the core particle, allowing long-term energy utilization without lifespan degradation
Solution Approach 2:
The patent uses composite materials in the core-shell structure where the shell material is specifically chosen to provide mechanical strength and stress resistance. This composite configuration protects the core from cracking during repeated cycling, resolving the contradiction between energy utilization and lifespan
4Quantity of substance
If primary particle size is increased to improve capacity, then capacity is improved, but resistance increases due to cracks
Solution Approach 1:
The patent applies segmentation by dividing the particle into core and shell regions. This allows the core to maintain large size for capacity while the shell provides a protective function that prevents crack formation, thereby maintaining low resistance despite the large primary particle size
Solution Approach 2:
The patent applies local quality by creating different structural properties in different regions. The core region is optimized for capacity with large size, while the shell region is optimized for mechanical integrity and crack prevention, allowing the particle to simultaneously achieve high capacity and low resistance
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 improves the lifespan and high-rate characteristics of lithium secondary batteries by reducing gas generation and increasing lithium ion diffusion efficiency, while maintaining high energy density.
Implementation Method 1
lithium phosphate is present in the porous core portion, between the plurality of primary particles, and on the surface of the secondary particle
Implementation Method 2
the Ni-based active material includes a porous inner portion including the porous core portion, and an outer portion including the shell portion, and the porous inner portion includes closed pores and is less in density than the outer portion
Data Source
AI summary
A nickel (Ni)-based active material for a lithium secondary battery, a preparing method thereof, and a lithium secondary battery including a positive electrode including the same. The Ni-based active material 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, and lithium phosphate is in the porous core portion, between the plurality of primary particles, and on the surface of the secondary particle. The Ni-based active material includes a porous inner portion including the porous core portion; and an outer portion comprising the the shell portion, and the Ni-based active material includes the porous inner portion having closed pores and the outer portion, wherein the porous inner portion has a density less than that of the outer portion, and the Ni-based active material has a net density of 4.7 g/cc or less.