Nickel-Rich Cathode Material With Cobalt-Rich Shell Stability
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Solution Overview
Problem
Lithium secondary batteries face issues with operational stability and reliability due to the generation of by-products when lithium metal oxide is exposed to the atmosphere or contacts the electrolyte, leading to reduced lifespan and stability.
Innovation Solution
A cathode active material for lithium secondary batteries is developed, comprising a lithium metal oxide particle with a core part and a shell part, where the shell part has a higher cobalt content than the core part, acting as a surface coating to enhance chemical stability and reduce surface resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal oxide is used as cathode active material to achieve high capacity and high output, then energy density and power are improved, but chemical stability and operational reliability deteriorate due to side reactions with atmosphere and electrolyte
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core region contains high nickel content (0.6-0.95) for high capacity and output, while the shell region contains high cobalt content (0.05-0.3) for chemical stability. This spatial differentiation of composition allows each region to perform its specific function optimally without compromise
Solution Approach 2:
The patent uses composite materials by combining nickel-rich lithium metal oxide core with cobalt-rich surface shell to create a composite cathode active material. The composite structure integrates the high capacity advantage of nickel with the high stability advantage of cobalt, achieving both high energy density and operational reliability
2Quantity of substance
If high nickel content (70 mol % or more) is used in lithium metal oxide to improve capacity, then energy density is improved, but chemical stability deteriorates due to increased surface reactivity
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core region contains high nickel content (0.6-0.95) for high capacity and output, while the shell region contains high cobalt content (0.05-0.3) for chemical stability. This spatial differentiation of composition allows each region to perform its specific function optimally without compromise
Solution Approach 2:
The cobalt-rich shell acts as an intermediary layer between the nickel-rich core and the external environment (atmosphere and electrolyte). This intermediary shell protects the reactive nickel core from direct exposure to harmful external factors, preventing by-product formation while maintaining high capacity
Data Source
AI summary
A cathode active material for a lithium secondary battery according to embodiments of the present invention includes a lithium metal oxide particle which includes a core part and a shell part and contains nickel (Ni), cobalt (Co) and manganese (Mn). A total Ni content of the lithium metal oxide particle is 70 mol % or more based on a total 100 mol % of Ni, Co and Mn. The shell part includes a depth region in a range of 10 to 100 nm from a surface of the lithium metal oxide particle, and a Co content thereof in the depth region is 1.4 to 6 times a Co content of the core part. Stability of the lithium secondary battery may be improved through surface treatment using high content of Co.