Radial Nickel Precursor Structure for Shorter Li-Ion Diffusion Paths
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing nickel-based cathode materials for lithium-ion batteries face challenges in coping with volume expansion and contraction during charging and discharging, leading to suboptimal power and cycling performance due to their compact internal and loose external structure.
Innovation Solution
A radially-structured nickel-based precursor with a loose and porous network-structured core and uniformly arranged radial strip-shaped primary crystal grains is developed, along with a preparation method involving controlled pH and ammonia concentration to achieve a stable and continuous production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a compact internal and loose external structure is used in nickel-based cathode materials, then the material structure is stable, but the contact area with electrolyte is reduced and lithium ion transmission path is lengthened
Solution Approach 1:
The cathode material structure is segmented into multiple hierarchical levels: micro-scale spherical secondary particles composed of nanoscale primary crystal grains arranged radially, with further segmentation into hollow interior and outer shell regions. This multi-level segmentation increases the effective contact area with electrolyte while maintaining structural stability through the hierarchical organization.
Solution Approach 2:
The invention introduces a hollow interior structure within the spherical secondary particles, creating porous spaces that increase electrolyte contact area. The hollow structure is formed by controlling the aggregation of primary crystal grains during precipitation, leaving void spaces that facilitate ion transport and electrolyte penetration throughout the material.
2Stability of the object's composition
If a compact internal and loose external structure is used in nickel-based cathode materials, then the material structure is stable, but the lithium ion transmission path is lengthened
Solution Approach 1:
The invention adopts spherical secondary particle morphology with radial arrangement of primary crystal grains. The spherical shape provides uniform stress distribution and stable structure, while the radial orientation of crystal grains creates direct transmission pathways from the outer surface to the hollow interior, shortening the lithium ion diffusion path compared to dense compact structures.
Solution Approach 2:
The invention transitions from a two-dimensional surface contact model to a three-dimensional volumetric contact model by creating hollow interiors and radial grain structures. This dimensional transformation allows lithium ions to access active material throughout the particle volume, not just at the surface, effectively shortening transmission paths.
3Stability of the object's composition
If a compact internal and loose external structure is used in nickel-based cathode materials, then the material structure is stable, but the deformation stress during charging and discharging is increased
Solution Approach 1:
The hollow interior structure acts as a pre-designed cushioning space that accommodates volume expansion and contraction of the cathode material during charging and discharging cycles. This void space absorbs deformation stress before it propagates through the entire particle structure, preventing crack formation and maintaining structural stability.
Solution Approach 2:
The outer shell composed of radially arranged primary crystal grains forms a flexible structure that can elastically deform during ion insertion and extraction. The radial arrangement allows the shell to expand and contract uniformly, distributing mechanical stress throughout the structure rather than concentrating it at specific points.
4Length of moving object
If radial arrangement of primary crystal grains is implemented, then the lithium ion transmission path is shortened, but the manufacturing complexity is increased
Solution Approach 1:
The invention utilizes self-assembly mechanisms during the precipitation process where primary crystal grains automatically arrange themselves in radial patterns around hollow cores. This self-organization occurs through controlled chemical precipitation conditions, eliminating the need for complex external alignment equipment or post-synthesis processing steps to achieve the radial structure.
Solution Approach 2:
The radial structure is formed by optimizing precipitation parameters including pH control, temperature, mixing rate, and precursor concentration. By adjusting these chemical parameters, the system naturally evolves into the desired radial morphology through controlled nucleation and growth processes, simplifying the manufacturing approach compared to mechanical or top-down methods.
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 radially-structured nickel-based precursor enhances the contact area with the electrolyte, shortens the lithium ion transmission path, and alleviates deformation stress, thereby improving the cycling performance and suitability for high-power battery applications.
Implementation Method 1
the secondary sphere has a loose and porous network-structured core inside
Implementation Method 2
the precursor is prepared in stages by a batch process. In a nucleation stage, under fast stirring, crystal nuclei with a compact texture are prepared
Data Source
AI summary
The present invention discloses a radially-structured nickel-based precursor and a preparation method thereof. An overall shape of the precursor is a secondary sphere formed by agglomeration of primary crystal grains; and the secondary sphere has a loose and porous network core inside and uniform and regular strip primary crystal grains outside, and the strip primary crystal grains grow outward perpendicularly to a surface of the core and are arranged radially and closely. The precursor structure of the present invention is more suitable for high-power battery cathode materials. The internal loose structure is more likely to form a void in the center during a preparation process of a cathode material, which helps to expand a contact area between an active material and an electrolyte.