Core-Shell Cathode Material With Porous Buffer for Li-Ion Rate and Life
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Solution Overview
Problem
Lithium secondary batteries face rapid degradation in life and performance due to electrolyte decomposition, active material deterioration, and increased inner resistance, especially at high temperatures, limiting their capacity and rate capability.
Innovation Solution
A positive electrode active material with a core-shell structure, featuring a first lithium complex metal oxide core, a second lithium complex metal oxide shell with radial crystal orientation, and a buffer layer with pores and a three-dimensional network structure, enhancing structural stability and reactivity with the electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If large particles are used to increase packing density, then energy per unit volume increases, but surface area and active area contact with electrolyte decrease, resulting in low rate capability and initial capacity
Solution Approach 1:
The patent divides the particle into a core-shell structure where the core contains large particles for high packing density and the shell contains fine particles for high surface area. This segmentation allows both large and small particles to coexist in a single composite structure, simultaneously achieving high volumetric energy density and high rate capability.
Solution Approach 2:
The patent embeds fine particles within the shell layer that surrounds the core particles, creating a nested core-shell structure. The fine particles in the shell provide extensive surface area for electrolyte contact while the core maintains high packing density, effectively nesting different particle size functions within one another.
2Duration of action of moving object
If LiCoO2 is used for excellent life property and charge discharge efficiency, then performance is improved, but structural stability is low, limiting high capacity applications
Solution Approach 1:
The patent creates a composite core-shell structure where the core uses LiCoO2 for excellent life property and charge-discharge efficiency, while the shell uses materials with high structural stability. This composite structure allows the LiCoO2 core to maintain its superior electrochemical performance while being protected by the stable shell structure during high-capacity operations.
3Quantity of substance
If LiNiO2 is used for high discharge capacity, then capacity is improved, but thermal stability and cycle property are poor
Solution Approach 1:
The patent applies local quality by concentrating the high-capacity LiNiO2 material in the core region where it can maximize discharge capacity, while placing thermally stable materials in the shell region that provides thermal management and structural protection. This spatial differentiation of material properties allows high capacity with improved thermal stability.
4Object-affected harmful factors
If LiMn2O4 is used for excellent thermal safety and low costs, then safety and cost are improved, but capacity is small and high temperature property is poor
Solution Approach 1:
The patent creates a multi-functional core-shell structure where the LiMn2O4 shell provides thermal safety and structural stability, while the inner core provides high capacity. The shell material serves multiple functions: thermal management, structural support, and ion transport, while the core focuses on maximizing capacity, achieving universality across different functional requirements.
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 core-shell structure minimizes material destruction during electrode preparation, maximizes electrolyte interaction, and facilitates lithium ion intercalation, resulting in improved output and life properties, suitable for high-capacity and long-life battery applications.
Implementation Method 1
a buffer layer located between the core and the shell, wherein the buffer layer includes a pore and a three-dimensional network structure of a third lithium complex metal oxide which is connecting the core and the shell
Implementation Method 2
A positive electrode active material with a core-shell structure, featuring a first lithium complex metal oxide core, a second lithium complex metal oxide shell with radial crystal orientation, and a buffer layer with pores and a three-dimensional network structure, enhancing structural stability and reactivity with the electrolyte
Implementation Method 3
a buffer layer located between the core and the shell, wherein the buffer layer includes a pore and a three-dimensional network structure
Implementation Method 4
a second lithium complex metal oxide shell with radial crystal orientation, and a buffer layer with pores and a three-dimensional network structure, enhancing structural stability and reactivity with the electrolyte
Data Source
AI summary
The present invention relates to a positive electrode active material for a lithium secondary battery, a method for preparing the same and a lithium secondary battery including the same, the positive electrode active material includes a core including a first lithium complex metal oxide, and a shell located surrounding the core and including a second lithium complex metal oxide, and further includes a buffer layer located between the core and the shell, wherein the buffer layer includes a pore, and a three-dimensional network structure of a third lithium complex metal oxide which is connecting the core and the shell, and accordingly, minimizing destruction of the active material caused by a rolling process during the electrode preparation, and maximizing reactivity with an electrolyte liquid.