Composite Hydroxide Precursors for High-Initial-Efficiency Li Batteries
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Solution Overview
Problem
Lithium secondary batteries require further improvements in initial efficiency as their application fields develop.
Innovation Solution
A metal composite hydroxide is used as a precursor for the positive electrode active material, characterized by specific properties such as average particle strength, molar ratio of manganese to cobalt, BET specific surface area, and average particle diameter, produced through a method involving mixing with a lithium compound and calcination in an oxygen-containing atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metal composite hydroxide is used as precursor, then battery durability and output characteristics are improved, but initial efficiency remains insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling multiple parameters of the metal composite hydroxide: average particle strength (10-45 MPa), BET specific surface area (5-40 m²/g), average particle diameter (3-5 μm), and molar ratios of metal elements. These parameter optimizations resolve the contradiction by achieving both high initial efficiency and maintained durability through balanced particle properties
2Area of stationary object
If particle size is reduced to improve surface area, then reactivity increases, but particle strength decreases
Solution Approach 1:
The patent resolves this contradiction through parameter changes by maintaining particle diameter within 3-5 μm while controlling particle strength to 10-45 MPa and specific surface area to 5-40 m²/g. This balanced parameter range achieves sufficient reactivity surface area while preventing particle fragmentation during battery operation
Solution Approach 2:
The patent employs composite materials by creating a metal composite hydroxide containing multiple metal elements (Ni, Co, Mn, and optionally other elements) with specific molar ratios. This composite structure provides both the surface area needed for reactivity and the structural strength required to prevent particle breakdown
3Power
If cobalt content is increased to improve battery performance, then output characteristics improve, but material cost increases
Solution Approach 1:
The patent applies parameter changes by optimizing the molar ratio of metal elements, specifically maintaining Mn/Co ratio greater than 1.0 and controlling Ni/Co ratio within 0.5-2.0. This parameter optimization achieves high output characteristics while reducing cobalt content compared to conventional formulations, thereby lowering material costs
Solution Approach 2:
The patent applies local quality by creating non-uniform distribution of metal elements within the composite hydroxide particles. The specific molar ratios and particle structure ensure that cobalt is strategically positioned to maximize output characteristics while minimizing overall cobalt content required
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 method enables the production of a lithium secondary battery with high initial efficiency, improving electrode structure and maintaining crystallinity and anisotropy.
Implementation Method 1
a calcination step for calcining the obtained mixture at a temperature of 500° C. or higher and 1,000° C. or lower in an oxygen-containing atmosphere
Data Source
AI summary
The present invention relates to a metal composite hydroxide used as a precursor of a positive electrode active material for a lithium secondary battery, said metal composite hydroxide comprising at least one metal element selected from the group consisting of Ni, Co, and Mn, and satisfying all of the following requirements (1) to (4):(1) An average particle strength is 10 MPa or more and less than 45 MPa;(2) A molar ratio (Mn/Co) of manganese to cobalt is more than 1.0;(3) A BET specific surface area is less than 40 m2/g;(4) An average particle diameter D50 is 4 μm or less.