Layered Cathode Active Material for Uniform Metal Dispersion
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Solution Overview
Problem
Lithium secondary batteries face challenges with non-uniform dispersion of transition metals, leading to poor electrochemical characteristics and reduced capacity, particularly due to the use of cobalt and high amounts of nickel, which are costly and pose resource risks.
Innovation Solution
A cathode active material with a lithium transition metal composite oxide having a layered structure, specifically expressed by the General Formula LimNixMnyTizO2, where titanium is added to LiNi0.5Mn0.5O2, optimizing the chemical composition and lattice constants to ensure uniform dispersion of transition metals, thereby reducing nickel usage and enhancing charge and discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cobalt is used as a cathode active material component, then electrochemical characteristics are improved, but cost increases and resource risk increases
Solution Approach 1:
The patent replaces expensive cobalt with a combination of nickel and manganese, which are cheaper and more abundant materials. The specific composition LiNi0.5Mn0.5O2 uses readily available transition metals to achieve the desired electrochemical performance without relying on scarce cobalt resources.
Solution Approach 2:
The patent creates a composite oxide material combining nickel, manganese, and lithium in specific ratios. This composite approach LiNi0.5Mn0.5O2 leverages the complementary properties of nickel (high capacity) and manganese (stability) to achieve both good electrochemical characteristics and cost-effectiveness.
2Quantity of substance
If high amounts of nickel are used to increase capacity, then charge and discharge capacity is improved, but uniform dispersion of transition metals deteriorates
Solution Approach 1:
The patent optimizes the stoichiometric parameters of the LiNi0.5Mn0.5O2 compound, specifically controlling the nickel-to-manganese ratio and lithium content. By adjusting these compositional parameters within precise ranges, the patent achieves both high capacity and uniform transition metal dispersion, resolving the contradiction between capacity and compositional stability.
3Ease of manufacture
If transition metals are not uniformly dispersed, then manufacturing is simplified, but electrochemical characteristics deteriorate
Solution Approach 1:
The patent ensures uniform distribution of nickel and manganese atoms throughout the crystal lattice structure of LiNi0.5Mn0.5O2. This uniform local composition at the atomic level is achieved through controlled synthesis conditions, ensuring that every region of the material has the same transition metal ratio, which is critical for consistent electrochemical performance.
Data Source
AI summary
A cathode active material for a lithium secondary battery contains a lithium transition metal composite oxide as a main component, the lithium transition metal composite oxide is in a form of particles having a layered structure of a lithium layer and a transition metal-lithium layer, the lithium transition metal composite oxide is expressed by General Formula (1) LimNixMnyTizO2 (in the formula, m is in a range of 1.0<m≤1.1, x is in a range of 0.4≤x<0.5, y is in a range of 0.3<y<0.5, and z is in a range of 0<z≤0.133), and as lattice constants (a, c, and c/a) of the lithium transition metal composite oxide, an a-axis length is 2.886 Å to 2.900 Å, a c-axis length is 14.29 Å to 14.35 Å, and c/a is 4.940 to 4.960.