Core-Shell High-Nickel Cathode Material for Faster Lithium Ion Transport
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Solution Overview
Problem
Existing methods for manufacturing positive electrode materials with high nickel content face challenges such as long co-precipitation times, low productivity, and increased costs, while requiring improvements in initial efficiency, life, output, and stability for high-capacity lithium secondary batteries.
Innovation Solution
A positive electrode active material with a core-shell structure is developed, where the shell comprises acicular particles oriented radially and a comb-like structure is formed during charging, facilitated by a specific chemical composition and heat treatment process, allowing easy lithium ion intercalation without a concentration gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a concentration gradient-type positive electrode material is used to improve stability, then shell portion stability is improved, but co-precipitation time increases and productivity decreases
Solution Approach 1:
The patent applies local quality by creating a shell portion with specific acicular particles that have different properties from the core. The shell contains particles with aspect ratios of 2-30 that form a protective layer with enhanced stability characteristics, while the core maintains high nickel content for capacity. This localized structural differentiation improves shell stability without requiring complex concentration gradient manufacturing processes.
Solution Approach 2:
The patent changes physical parameters by controlling particle morphology (aspect ratio of 2-30) and crystal structure in the shell portion through specific heat treatment conditions (900-1100°C). By adjusting these physical parameters during manufacturing, the shell achieves enhanced stability without requiring extended co-precipitation times, thus maintaining productivity while improving reliability.
2Quantity of substance
If high nickel content is used to increase capacity, then battery capacity is improved, but initial efficiency and stability deteriorate
Solution Approach 1:
The patent segments the positive electrode material into distinct core and shell portions with different compositions and structures. The core contains high nickel content (Ni ≥ 0.8) for high capacity, while the shell contains acicular particles that provide structural stability and protect the high-nickel core. This segmentation allows the material to simultaneously achieve high capacity and improved stability, resolving the contradiction between quantity and reliability.
Solution Approach 2:
The patent creates a composite material structure where the shell portion contains acicular particles embedded in a matrix material. This composite structure combines the high capacity characteristics of high-nickel materials with the stabilizing effect of the acicular particle network, achieving both high battery capacity (≥240 mAh/g) and improved initial efficiency and cycle stability.
3Ease of operation
If acicular particles with high aspect ratio are formed in the shell, then lithium ion migration is facilitated, but manufacturing complexity increases
Solution Approach 1:
The patent controls the aspect ratio parameter of acicular particles within a specific range (2-30) to optimize lithium ion migration pathways. By maintaining particles within this aspect ratio range and controlling their distribution in the shell, the structure facilitates ion transport without requiring excessively complex manufacturing processes. The aspect ratio control is achieved through standard ceramic processing techniques including controlled sintering at 900-1100°C.
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 core-shell structure enhances lithium ion migration pathways, improving battery capacity, initial efficiency, and reducing resistance, while suppressing micro-cracks to extend battery life.
Implementation Method 1
a structure in which lithium ions can be easily intercalated on a surface of a positive electrode material
Implementation Method 2
the shell portion may be converted into a comb-like structure in which a pore channel is formed in the direction from the core portion toward the shell portion
Implementation Method 3
heat-treating the mixture to form a shell portion
Implementation Method 4
a raw material of the niobium (Nb) oxide may include two or more different crystal structures
Data Source
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AI summary
The present embodiments relate to a positive electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery including the same. A positive electrode active material for a lithium secondary battery according to an embodiment includes a core portion, and a shell portion positioned on a surface of the core portion, wherein the shell portion includes acicular particles whose major axes are oriented in a direction from the core portion toward the shell portion, and the positive electrode active material is represented by the following chemical formula 1. [Chemical Formula 1] Li1+q(NixCoyMnz)1-w(ZraNbb)wO2 In Chemical Formula 1, q, x, y, z, a, b, and w are 0≤q≤0.2, 0.0032<w<0.013, 0.7≤x<1.0, 0<y<0.3, 0<z<0.3, x+y+z=1, 0.2≤a≤0.7, 0.3≤b≤0.8, and a+b=1, respectively.