Composite Cathode Materials for Lithium-Ion Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-rich cathode materials for lithium-ion batteries suffer from high irreversible capacity loss and poor cycling stability, which limits their energy density and calendar life, especially when used in hybrid and electric vehicles.
Innovation Solution
A composite cathode material comprising Li[M1-xLix]O2 or yLi2MnO3.(1−y)LiMO2 (M=Ni, Co, Mn) blended with LiMn1.5Ti0.5O4 and LiMn1.5Ni0.5O4, where the particles are evenly distributed to reduce irreversible capacity loss and enhance cycling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If lithium-rich cathode materials are used to achieve high specific capacity, then discharge capability is improved, but irreversible capacity loss increases
Solution Approach 1:
The patent creates a composite cathode material by coating lithium-rich layered oxide particles with a spinel layer (LiMn2O4 or LiMn1.5Ni0.5O4). This composite structure combines the high capacity advantage of lithium-rich materials with the stability benefits of spinel, reducing irreversible capacity loss while maintaining discharge capability. The spinel coating acts as a protective layer that prevents direct exposure of the lithium-rich core to the electrolyte.
Solution Approach 2:
The patent modifies the surface composition and structure of the cathode material by introducing a spinel phase coating with specific molar ratios of Li, Mn, and Ni. This parameter change at the surface level alters the electrochemical behavior, reducing capacity loss without significantly compromising the bulk material's high capacity characteristics.
2Power
If lithium-rich cathode materials are charged to 4.8 V to extract lithium and form MnO2, then discharge capability is improved, but cycling stability deteriorates
Solution Approach 1:
The spinel-coated composite structure protects the lithium-rich core during high-voltage charging to 4.8 V. The spinel layer accommodates volume changes and prevents structural degradation, enabling stable cycling while maintaining the ability to extract lithium and form MnO2 for high discharge capability.
Solution Approach 2:
The spinel coating is applied beforehand to cushion and protect the lithium-rich layered oxide from structural degradation during high-voltage charging. This pre-protective layer prevents Jahn-Teller distortion and oxygen loss that would otherwise occur during charging to 4.8 V, thereby maintaining cycling stability.
3Loss of energy
If acid treatment is applied to reduce irreversible capacity loss, then electrochemical performance is improved, but cycling stability and rate capability are adversely affected
Solution Approach 1:
The spinel layer acts as an intermediary protective barrier between the lithium-rich layered oxide core and the electrolyte. This physical/chemical intermediary reduces irreversible capacity loss by preventing direct harmful interactions, while simultaneously protecting the underlying material from acid treatment damage and maintaining cycling stability and rate capability.
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 composite cathode material achieves a first discharge capacity of 190-255 mAh/g, a capacity retention of 80-95% after 40 cycles, and a columbic efficiency of 75-95%, with reduced charge transfer resistance, improving the overall performance of lithium-ion batteries.
Implementation Method 1
it is believed to stabilize the electrochemically active LiMO2 component by maintaining the cathode structure and to improve the discharge capability by extracting lithium concomitant with release of oxygen (a net loss of Li2O) to form MnO2 at high potential
Implementation Method 2
In these composites, the lithium insertion hosts act to accommodate the lithium ions that could not be inserted back into layered lattices after the first charge
Implementation Method 3
LiMn2O4 can not only de-intercalate one unit of Li from the 8a tetrahedral sites per formula at 4 V, but also can intercalate an additional unit of Li into the 16c octahedral sites at 3 V
Implementation Method 4
LiMn2O4 can not only de-intercalate one unit of Li from the 8a tetrahedral sites per formula at 4 V, but also can intercalate an additional unit of Li into the 16c octahedral sites at 3 V
Data Source
AI summary
Composite materials for a cathode of an electrochemical cell. The composite materials comprise Li[M1−xLix]O2 or yLi2MnO3.(1−y)LiMO2 (M=Ni, Co, Mn, 0<x<0.5, 0<y<1), and at least one of LiMn1.5Ti0.5O4 and LiMn1.5Ni0.5O4. A Li-ion electrochemical cell including a cathode comprising the composite materials is also provided. The Li-ion electrochemical cell controls irreversible capacity loss and maintain a good cycling stability.