Silicon-Modified LNMO Cathode Morphology for Capacity Retention
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Solution Overview
Problem
Current lithium-ion batteries face challenges with poor safety, low energy and power density, and capacity fading due to degradation of the electrolyte and structural instability of high-voltage spinel LiNi0.5Mn1.5O4 (LNMO) cathode materials.
Innovation Solution
A silicon-modified Lithium-Nickel-Manganese-Oxide (LNMO) material with specific particle morphology is developed, where silicon is incorporated into both the surface and bulk of the LNMO material through high-temperature synthesis using an organo silicate as the Si-source, enhancing the material's stability and electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-voltage spinel LNMO is used as cathode material, then energy and power density are improved, but capacity fading and safety issues occur due to electrolyte degradation and structural instability
Solution Approach 1:
A magnesium aluminate spinel coating layer is applied as an intermediary between the LNMO cathode material and the electrolyte. This coating layer acts as a protective mediator that prevents direct contact and harmful reactions between the electrolyte and LNMO surface, thereby reducing capacity fading and improving capacity retention while maintaining the high voltage and energy density characteristics of LNMO
Solution Approach 2:
The invention creates a composite structure by combining LNMO core material with a magnesium aluminate spinel coating layer. This composite material approach allows the inner LNMO to provide high energy density while the outer coating provides structural stability and chemical inertness, resolving the contradiction between high performance and reliability
2Temperature
If high-voltage spinel LNMO is used as cathode material, then operating voltage is improved, but structural instability and metal ion dissolution occur in the electrolyte
Solution Approach 1:
The magnesium aluminate spinel coating serves as a stable intermediary layer that protects the structurally sensitive LNMO core from direct exposure to the electrolyte environment. This coating maintains the high operating voltage of LNMO while preventing structural degradation and metal ion dissolution by providing a chemically stable barrier
Solution Approach 2:
The coating is applied specifically to the surface region of the LNMO particles, creating a localized protective layer. This allows the bulk LNMO material to maintain its high voltage electrochemical properties while only the surface region provides the structural stability and chemical resistance needed to prevent ion dissolution
3Reliability
If surface modification with oxide coatings is applied to LNMO, then capacity retention is improved, but interfacial resistance increases which hinders Li-ion mobility
Solution Approach 1:
The coating thickness is precisely controlled at approximately 5 nm, which is thin enough to allow efficient Li-ion transport through the coating layer while still providing sufficient protection to improve capacity retention. This parameter optimization resolves the contradiction by finding the optimal thickness that balances protection and ion conductivity
Solution Approach 2:
The magnesium aluminate spinel coating provides localized protection at the electrode-electrolyte interface while maintaining high Li-ion conductivity throughout the coating layer. The coating's specific crystal structure and composition enable it to provide barrier functionality without creating significant resistance to ion transport
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 silicon modification significantly improves the cycling and capacity retention performance of the LNMO material, providing enhanced stability and electrochemical performance, especially at elevated temperatures, making it suitable for high-capacity cathode applications in lithium-ion batteries.
Implementation Method 1
silicon is incorporated into both the surface and bulk of the LNMO material through high-temperature synthesis using an organo silicate as the Si-source
Data Source
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AI summary
The invention provides an LNMO particulate material that comprises secondary particles, wherein the secondary particles are composed of a multitude of crystals, and said crystals are composed of a multitude of crystallites, wherein a D50 particle size of the secondary particles is between 4.0 µm and 25 µm, as measured by laser diffraction according to ISO 13320:2020, and wherein a D50 particle size of the crystals is between 0.5 µm and 7.0 µm as measured by scanning electron microscope (SEM), and wherein, the LNMO particulate material is silicon modified. In other aspects, the invention further provides a process for the production of silicon modified Lithium-Nickel-Manganese-Oxide (LNMO) particulate material and a silicon modified LNMO material obtainable by the process according to the present invention.