Nickel-Cobalt Oxide Cathode Structure for Low-Polarization Batteries
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Solution Overview
Problem
Existing lithium-ion batteries face issues with increased nickel content leading to side reactions, particle cracking, and poor lithium ion diffusion due to large particle sizes, affecting cycle life and safety performance.
Innovation Solution
A lithium nickel cobalt oxide composite oxide cathode material with controlled peak separation (0.7≤α≤2.0) and a preparation method involving stepwise heating stages and constant temperature sintering to manage particle size, strength, and internal defects, enhancing lithium ion diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel content in ternary cathode materials is increased to increase capacity, then the capacity of cathode materials is improved, but side reactions between materials and electrolyte solutions increase and particle cracking occurs
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the interior maintains high nickel content for capacity while the surface has modified composition and structure to reduce side reactions. The surface treatment creates a protective layer that locally changes the chemical environment at the particle surface, allowing high bulk nickel content without proportional increase in surface degradation.
Solution Approach 2:
The patent uses composite materials by combining high-nickel cathode material with surface coating layers or modifying the surface structure to create a composite system. This composite structure allows the bulk material to provide high capacity while the surface composite layer provides protection against side reactions and mechanical degradation.
2Quantity of substance
If nickel content in ternary cathode materials is increased to increase capacity, then the capacity of cathode materials is improved, but particle cracking and pulverization occur due to increased internal stress
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the interior maintains high nickel content for capacity while the surface has modified composition and structure to reduce side reactions. The surface treatment creates a protective layer that locally changes the chemical environment at the particle surface, allowing high bulk nickel content without proportional increase in surface degradation.
Solution Approach 2:
The patent applies beforehand cushioning by pre-treating the particle surfaces or introducing surface layers before the particles undergo charge-discharge cycling. This surface preparation creates a buffer zone that absorbs and distributes internal stresses during lithium insertion/extraction, preventing stress concentration that would lead to cracking and pulverization.
3Ease of manufacture
If particle size of cathode materials is large, then manufacturing is easier, but lithium ion diffusion is poor leading to electrochemical polarization
Solution Approach 1:
The patent applies segmentation by dividing the cathode material into smaller primary particles or creating a hierarchical structure with internal porosity. This segmentation increases the surface area to volume ratio, shortening lithium ion diffusion paths while maintaining reasonable manufacturing characteristics. The material is divided into multiple smaller units that collectively provide both good diffusion and manufacturability.
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 solution improves cycle stability and rate performance by controlling particle size, strength, and internal defects, reducing cracking and pulverization, and balancing energy density and electrochemical performance.
Implementation Method 1
In an XRD pattern of the cathode material, a characteristic peak of a crystal face (104) includes a (104)−Kα1 diffraction peak and a (104)−Kα2 diffraction peak after peak splitting
Implementation Method 2
subjecting the mixture to primary sintering and pulverization to obtain a cathode material. The primary sintering includes N stepwise heating stages and M constant temperature stages
Data Source
AI summary
Provided is a cathode material and a preparation method therefor, and a secondary battery. The cathode material is a lithium nickel cobalt oxide composite oxide. In an XRD pattern of the cathode material, a characteristic peak of a crystal face (104) includes a (104)−Kα1 diffraction peak and a (104)−Kα2 diffraction peak after peak splitting, a separation value between the (104)−Kα1 diffraction peak and the (104)−Kα2 diffraction peak is a, and 0.7≤α≤2.0. The cathode material has suitable particle size, good particle strength and sufficient internal defects, which are conducive to reducing the phenomenon of polarization of the cathode material, such that the secondary battery based on the cathode material has both better cycle stability and rate performance.