Core-Shell Lithium Manganese Oxide Cathode for 3V Region Conductivity
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Solution Overview
Problem
Spinel lithium manganese oxides exhibit reduced capacity and short cycle lifespan in the 3V region due to phase transition and low electrical conductivity of the tetragonal structure, making their utilization challenging in lithium secondary batteries.
Innovation Solution
A cathode active material with a lithium manganese-based oxide having a core-shell phase transition from cubic to tetragonal structure, incorporating a conductive material at the shell to enhance electrical conductivity, and a complex of carbonaceous materials with different particle diameters to improve reaction participation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If spinel lithium manganese oxide is utilized in the 3V region, then thermal stability and low cost are achieved, but capacity and cycle lifespan are significantly reduced due to phase transition and low electrical conductivity
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the shell region has different properties from the core. Specifically, the shell is modified with carbonaceous material and metal elements to improve electrical conductivity and structural stability, while the core maintains the original spinel lithium manganese oxide composition for cost-effectiveness and thermal stability. This local differentiation allows the shell to compensate for the conductivity issues in the 3V region without sacrificing the overall cost advantage.
Solution Approach 2:
The patent employs composite materials by combining spinel lithium manganese oxide with carbonaceous material (such as graphite, carbon black, or amorphous carbon) and metal elements (such as Ni, Co, Mn, Al, or Si) to form a core-shell structured composite. This composite structure synergistically combines the low cost and thermal stability of lithium manganese oxide with the high electrical conductivity and structural stability of carbon and metal components, thereby improving cycle lifespan and capacity in the 3V region.
2Quantity of substance
If phase transition from cubic to tetragonal structure occurs during discharging to 3V region, then capacity is achieved, but electrical conductivity of the tetragonal structure is low, reducing reaction efficiency
Solution Approach 1:
The patent uses carbonaceous material and metal elements as intermediaries in the shell region to mediate between the tetragonal phase and the electrolyte. These intermediary materials provide high electrical conductivity pathways that compensate for the low conductivity of the tetragonal structure, facilitating electron transport and improving reaction efficiency while allowing the capacity-giving phase transition to proceed.
Solution Approach 2:
The patent applies parameter changes by modifying the electrical conductivity parameter of the shell region through the addition of carbonaceous material and metal elements. This changes the electrical properties of the material in the 3V region, transforming it from a low-conductivity state to a high-conductivity state, thereby improving reaction efficiency without altering the capacity-providing phase transition behavior.
3Reliability
If uniform carbon coating is applied to improve conductivity, then electrical conductivity increases, but reaction participation is reduced due to large particle diameter
Solution Approach 1:
The patent applies segmentation by using a core-shell structure where the carbonaceous material and metal elements are concentrated in the shell region rather than uniformly distributed throughout the entire particle. This segmentation allows the inner core to maintain high reaction participation with the electrolyte while the outer shell provides the necessary electrical conductivity, thus resolving the trade-off between conductivity and reaction efficiency.
Solution Approach 2:
The patent uses local quality by concentrating the conductive materials (carbonaceous material and metal elements) specifically in the shell region adjacent to the electrolyte interface. This localized placement ensures that the materials providing high electrical conductivity are positioned exactly where they are most needed - at the reaction interface - while minimizing the amount of inactive material and maintaining high reaction participation.
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 a cathode active material with high capacity and long lifespan in the 3V region, improving electrical conductivity and reaction efficiency, thereby enhancing the performance of lithium secondary batteries.
Implementation Method 1
phase transition of a crystal structure occurs from a cubic structure to a tetragonal structure in a direction from the surface of a particle to the center of the particle during discharging to a 3V region
Implementation Method 2
includes a conductive material at the shell to improve electrical conductivity of the tetragonal structure
Data Source
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AI summary
Disclosed is a cathode active material including a lithium manganese-based oxide. The lithium manganese-based oxide has a spinel structure, exhibits core-shell phase transition by which phase transition of a crystal structure occurs from a cubic structure to a tetragonal structure in a direction from the surface of particles to the center of the particles during discharging to the 3V region, and includes a conductive material at the shell to improve electrical conductivity of the tetragonal structure.