Cathode active material for lithium secondary battery, method of preparing the same and lithium secondary battery including the same
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Solution Overview
Problem
Lithium secondary batteries face issues with degraded output characteristics and cycle life due to side reactions between the cathode active material and electrolyte, necessitating improved materials and manufacturing processes.
Innovation Solution
A cathode active material comprising lithium-transition metal oxide particles with a lithium-sulfur-metal-containing portion, controlled particle size and uniform sulfur distribution, achieved through a specific preparation method involving dry mixing, solvent addition, drying, and calcination, to enhance structural stability and reduce impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cathode active materials are used, then the battery can operate, but side reactions between the cathode active material and electrolyte occur, degrading output characteristics and cycle life
Solution Approach 1:
A lithium-sulfur-metal-containing portion is introduced as an intermediary layer between the cathode active material particles and the electrolyte. This intermediary portion prevents direct contact and side reactions between the cathode active material and electrolyte, thereby improving cycle life and output characteristics while maintaining battery operation
Solution Approach 2:
The cathode active material is constructed as a composite structure where lithium-sulfur-metal-containing portions are positioned between primary particles or on the surface of secondary particles. This composite architecture combines the electrochemical activity of the cathode material with the protective and conductive properties of the lithium-sulfur-metal-containing portion
2Manufacturing precision
If the sulfur content is increased to improve uniformity, then the relative standard deviation decreases, but the manufacturing complexity increases
Solution Approach 1:
The sulfur compound and metal oxide are mixed with the cathode active material particles before the final sintering process. This preliminary mixing ensures uniform distribution of sulfur and metal components throughout the cathode material, achieving consistent sulfur signal values across particles while using a straightforward manufacturing sequence
Solution Approach 2:
The sulfur content is controlled within a specific range (3000-6000 ppm) and the sintering temperature is optimized (400-500°C) to achieve complete reaction and uniform distribution. By optimizing these parameters, the patent achieves low relative standard deviation (10.5% or less) without requiring complex multi-step manufacturing processes
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 results in improved output characteristics, cycle life, and high-temperature storage performance of lithium secondary batteries, reducing gas generation and maintaining capacity over time.
Implementation Method 1
a sulfur compound and a metal oxide are mixed with the first preliminary lithium-transition metal oxide particles... calcining the second preliminary lithium-transition metal oxide particles
Implementation Method 2
a solvent and the mixture are dried to prepare second preliminary lithium-transition metal oxide particles
Data Source
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AI summary
A cathode active material for a lithium secondary battery according to embodiments of the present disclosure comprises a lithium-sulfur-metal-containing portion and lithium-transition metal oxide particles having a minimum particle diameter (Dmin) of greater than 1 µm, wherein a relative standard deviation of the sulfur signal values of the lithium-transition metal oxide particles, as measured repeatedly ten times by X-ray photoelectron spectroscopy (XPS) analysis, is 10.5% or less.