Positive Electrode Coating for High-Ni LNCMO Cation Mixing
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Solution Overview
Problem
Lithium nickel-cobalt-manganese oxide (LNCMO) based positive electrode active materials with high Ni content face issues of cation mixing, leading to battery life deterioration and reduced capacity due to the tendency of Ni 3+ to reduce to stable Ni 2+, and coating these materials can further decrease battery capacity.
Innovation Solution
A positive electrode active material with a specific composition and surface coating, characterized by I003/I104 and (I102 + I006)/(I101) values within certain ranges, and a c-axis length of 14.1870 Å to 14.1893 Å, combined with an outer layer comprising different elements like Zr, Al, and B, to stabilize the structure and improve capacity and lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high Ni content LNCMO is used to increase battery capacity, then battery capacity is improved, but cation mixing occurs leading to battery life deterioration
Solution Approach 1:
The patent applies local quality by creating a dual-layer surface coating structure where the first coating layer (containing Al, Ti, and Zr) and second coating layer (containing B) are distributed on different portions of the particle surface. This localized differentiation allows specific regions to address cation mixing while preserving capacity in other regions, resolving the contradiction between high capacity and long lifetime.
Solution Approach 2:
The patent uses composite materials by combining multiple coating elements (Al, Ti, Zr, B) with the high-Ni LNCMO core material. The composite structure of core-shell design with different elemental compositions in each layer synergistically prevents cation mixing while maintaining high capacity, thus improving both reliability and capacity simultaneously.
2Reliability
If surface coating is applied to prevent cation mixing, then battery lifetime is improved, but battery capacity decreases
Solution Approach 1:
Instead of uniform coating that reduces capacity, the patent applies local quality by distributing different coating materials on different portions of the particle surface. The first coating layer with Al, Ti, and Zr addresses stability on certain regions, while the second layer with B addresses capacity maintenance on other regions, thus improving lifetime without sacrificing overall capacity.
Solution Approach 2:
The patent changes the parameters of the coating structure by controlling the thickness, composition, and spatial distribution of each coating layer. By optimizing these parameters (e.g., specific elemental ratios, layer thicknesses), the coating prevents cation mixing while minimizing capacity loss, resolving the contradiction between lifetime improvement and capacity maintenance.
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 proposed active material enhances both battery capacity and lifetime by stabilizing the crystal structure and preventing cation mixing, resulting in improved initial charging/discharging efficiency and high-temperature lifespan.
Implementation Method 1
sintering a first mixture comprising the transition metal hydroxide, a M1 component precursor, and a lithium compound to obtain a first lithium composite oxide
Implementation Method 2
sintering a second mixture comprising the first lithium composite oxide and a M2 component precursor to obtain a second lithium composite oxide
Implementation Method 3
heat-treating a third mixture comprising the dried second lithium composite oxide and a M3 component precursor
Data Source
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AI summary
A positive electrode active material of the present invention is capable of improving capacity and lifetime of a battery simultaneously, a battery of the present invention can have improved capacity and lifetime simultaneously, a method of the present invention is able to manufacture a positive electrode active material capable of improving capacity and lifetime of a battery simultaneously.