Core-Shell Cathode Material for Lithium Batteries
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Solution Overview
Problem
Nickel-based lithium metal oxides with high nickel content become structurally unstable and have sensitivity issues with sintering temperature, leading to low output characteristics and capacity, as higher temperatures result in larger crystal and particle sizes.
Innovation Solution
Development of nickel-based lithium metal oxide particles with a core-shell gradient structure doped with Zr and Al, where the nickel content decreases from the core to the shell, stabilizing the structure and controlling crystal and particle sizes, and a bi-modal particle size distribution is used to enhance energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the content of nickel (Ni) is increased to achieve high capacity, then the capacity is improved, but the structural stability deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell gradient structure where the nickel content varies spatially. The core region has high nickel content (0.7-0.95) to provide high capacity, while the shell region has lower nickel content (0.5-0.8) to ensure structural stability. This gradual transition from high-Ni core to low-Ni shell resolves the contradiction between capacity and structural stability.
Solution Approach 2:
The patent uses composite materials by combining nickel-based lithium metal oxide with other metal elements (Co, Mn, Al, Zr) in a layered structure. This composite approach allows the high-capacity nickel regions to coexist with structurally stable regions containing other metals, achieving both high capacity and structural stability simultaneously.
2Power
If the sintering temperature is increased to improve output characteristics, then the output characteristic is improved, but the crystal size and particle size increase leading to low capacity
Solution Approach 1:
The patent applies parameter changes by optimizing the sintering temperature to a specific range (700-900°C) and controlling the sintering time (5-20 hours). These parameter adjustments allow the formation of the desired core-shell gradient structure with controlled crystal size (50-200 nm) and particle size, achieving both good output characteristics and high capacity without excessive grain growth.
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 achieves high capacity and structural stability, improves output and life characteristics of lithium secondary batteries, and minimizes DCR resistance increase during high-temperature charge/discharge cycles.
Implementation Method 1
nickel-based lithium metal oxide particles doped with Zr and Al
Implementation Method 2
the nickel-based lithium metal oxide has a problem in that it is sensitive to the temperature at which the nickel-based metal hydroxide, which is a precursor thereof, and the lithium supply material are mixed and sintered
Data Source
AI summary
A cathode active material for a lithium secondary battery includes a nickel-based lithium metal oxide particle doped with Zr and Al. The nickel-based lithium metal oxide particle includes a core portion having a constant molar content of nickel, and a shell portion surrounding an outer surface of the core portion and having a concentration gradient in which a molar content of nickel gradually decreases in a direction from an interface with the core portion to an outermost periphery. The core portion and the shell portion are doped with Al and Zr.