Li-Rich Nickel-Manganese Cathode Precursor for Higher Volumetric Capacity
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Solution Overview
Problem
Lithium-manganese-rich (LMR) materials exhibit lower energy density per volume due to their relatively low content of LiNiO2 and high content of LiMnO2 and/or Li2MnO3, limiting their capacity compared to nickel-based positive electrode active materials.
Innovation Solution
A method involving a first heat-treatment of a nickel-manganese-based hydroxide at less than or equal to 500°C, followed by mixing with a lithium raw material at a specific molar ratio and a second heat-treatment at temperatures equal to or greater than 950°C, to produce a lithium nickel-manganese-based composite oxide, enhancing energy capacity and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LMR materials with high manganese content are used to achieve low cost and high capacity via O-redox, then energy capacity per weight is improved, but energy density (capacity per volume) is reduced
Solution Approach 1:
The patent divides the synthesis process into two distinct stages: first heat-treatment (≤500°C) to form the oxide precursor framework, and second heat-treatment (≥950°C) to achieve final densification and lithium incorporation. This segmentation allows optimization of each stage for different objectives - structural formation versus density enhancement - thereby resolving the contradiction between capacity and energy density.
Solution Approach 2:
The first heat-treatment step performs preliminary action by forming the oxide precursor with specific crystal structure (R-3 space group) and surface properties before the final lithium incorporation. This preliminary structuring enables the second heat-treatment to focus on densification and lithium diffusion, ultimately achieving both high capacity and high energy density in the final product.
2Ease of manufacture
If a single heat-treatment process is used, then manufacturing complexity is reduced, but manufacturing precision and material performance are compromised
Solution Approach 1:
The synthesis process is segmented into two distinct heat-treatment operations with different temperature ranges and objectives. The first heat-treatment (≤500°C) controls oxide precursor formation with specific crystal structure, while the second heat-treatment (≥950°C) controls lithium incorporation and final densification. This segmentation enables precise control of material composition and structure that cannot be achieved with a single heat-treatment process.
Solution Approach 2:
The patent utilizes parameter changes by varying temperature conditions between the two heat-treatment steps. The first step operates at lower temperatures (≤500°C) to form the oxide framework, while the second step operates at high temperatures (≥950°C) to achieve lithium diffusion and densification. This parameter variation enables precise control over material properties while maintaining manageable process complexity.
3Use of energy by moving object
If high lithium content is incorporated to increase energy capacity, then capacity per weight is improved, but weight-to-volume density is reduced
Solution Approach 1:
The first heat-treatment step performs preliminary action by establishing the oxide precursor framework with optimal porosity and surface area before lithium incorporation. This preliminary structuring creates a scaffold that accommodates lithium diffusion during the second heat-treatment while maintaining high density, thereby achieving both high capacity and high weight-to-volume density.
Solution Approach 2:
The patent employs parameter changes by controlling the lithium-to-metal molar ratio (greater than 1 and less than or equal to 2) and varying the second heat-treatment temperature (≥950°C). These parameter adjustments optimize lithium incorporation efficiency while maintaining high pellet density, resolving the contradiction between energy capacity and weight-to-volume density.
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 results in a lithium-manganese-rich positive electrode active material with improved energy capacity and weight-to-volume density, maximizing energy density and capacity per volume.
Implementation Method 1
subjecting a nickel-manganese-based hydroxide having a manganese content of about 34 mol % to about 50 mol % based on 100 mol % of a total metal to first heat-treatment at a temperature of less than or equal to about 500° C. to prepare a nickel-manganese-based oxide precursor
Implementation Method 2
mixing the nickel-manganese-based oxide and a lithium raw material such that a molar ratio of lithium of the lithium raw material to the total metal of the nickel-manganese-based oxide is greater than 1 and less than or equal to 2, and performing a second heat-treatment, to obtain a lithium-manganese-rich positive electrode active material including a lithium nickel-manganese-based composite oxide
Data Source
AI summary
A method for preparing a positive electrode active material, a precursor of a positive electrode active material including a lithium nickel-manganese-based composite oxide, the method including: preparing a nickel-manganese-based oxide precursor by subjecting a nickel-manganese-based hydroxide, having a manganese content of about 34 mol % to about 50 mol % based on 100 mol % of a total metal, to a first heat-treatment at a temperature of less than or equal to about 500° C.; mixing the nickel-manganese-based oxide precursor and a lithium raw material to form a mixture at a molar ratio of lithium of the lithium raw material to the total metal of the nickel-manganese-based oxide precursor being greater than about 1 and less thans or equal to about 2; and subjecting the mixture to a second heat-treatment.