High-Nickel Cathode Precursor Structure for Crystal Stability
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Solution Overview
Problem
High-nickel-based lithium oxide cathode active materials in lithium secondary batteries suffer from structural instability and side reactions with the electrolyte, leading to degraded lifespan and operational stability.
Innovation Solution
A cathode active material precursor with a nickel composite hydroxide structure and specific oxygen position in the Z-axis direction, combined with a lithium-nickel-based composite oxide, is used to maintain a stable layered structure and suppress impurity generation, ensuring improved structural and chemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel-based lithium oxide is used to increase battery capacity, then energy density and capacity are improved, but structural stability and chemical stability deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core contains high-nickel content (Ni≥80 mol%) for high capacity, while the outer shell contains lower-nickel content (Ni≤70 mol%) for enhanced stability. This spatial differentiation of nickel concentration allows each region to perform its optimal function - the core provides capacity while the shell provides structural protection.
Solution Approach 2:
The patent uses composite materials by combining high-nickel lithium oxide core with a stabilizing shell layer containing transition metals (Co, Mn, Ni) in specific ratios. The composite structure integrates the high-capacity advantage of high-nickel material with the high-stability advantage of lower-nickel material, achieving both high capacity and structural stability simultaneously.
2Quantity of substance
If high-nickel-based lithium oxide is used to increase battery capacity, then energy density is improved, but operational stability and lifespan deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-forming a stable shell structure around the high-nickel core before battery operation begins. This pre-protective shell prevents harmful side reactions between the high-nickel core and electrolyte during initial charging cycles, thereby ensuring long-term operational stability and lifespan from the outset.
Solution Approach 2:
The stable shell layer acts as an intermediary between the high-nickel core and the electrolyte. It mediates the interaction by providing a protective barrier that prevents direct contact between the reactive high-nickel material and the electrolyte, thereby maintaining operational stability while preserving the high energy density benefits.
3Quantity of substance
If high-nickel-based lithium oxide is used to increase battery capacity, then capacity is improved, but side reactions with electrolyte increase
Solution Approach 1:
The patent applies the taking out principle by extracting the high-nickel core from direct contact with the electrolyte and placing it within a protective shell structure. This separation removes the harmful interaction between high-nickel material and electrolyte while preserving the capacity benefits of the high-nickel core.
Solution Approach 2:
The shell layer serves as an intermediary barrier that prevents direct side reactions between the high-nickel core and the electrolyte. It allows ionic transport for battery function while blocking harmful chemical reactions, thereby maintaining high capacity with reduced side reactions.
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 enhances the high-temperature stability and capacity of lithium secondary batteries by maintaining a stable crystal structure and reducing side reactions, resulting in improved capacity retention and lifespan.
Implementation Method 1
a cathode active material precursor for a lithium secondary battery having improved structural and chemical stability... A cathode active material precursor for a lithium secondary battery has a structure of a nickel composite hydroxide. An oxygen position in a Z-axis direction measured by a Rietveld method in a space group P-3m crystal structure based on an X-ray diffraction (XRD) analysis is 0.200 or more.
Implementation Method 2
a side reaction with the electrolyte and an instability of a chemical structure may be easily caused in the high-nickel-based lithium oxide to degrade a life-span and an operational stability of the lithium secondary battery. Thus, a structural stability of the nickel-containing precursor may be needed to enhance a stability of the cathode active material.
Data Source
AI summary
A cathode active material precursor for a lithium secondary battery has a structure of a nickel composite hydroxide. An oxygen position in a Z-axis direction measured by a Rietveld method in a space group P-3m crystal structure based on an X-ray diffraction (XRD) analysis is 0.200 or more. A cathode active material and a lithium secondary battery having a stabilized crystal structure are provided using the cathode active material precursor.