Doped and Coated Cathode Material for High-Nickel Battery Stability
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Solution Overview
Problem
Lithium secondary batteries face challenges with thermal stability, cycle characteristics, and durability due to limitations in existing positive electrode active materials, such as LiCoO2's high cost and poor high-temperature stability, and LiMnO2's low capacity and conductivity issues.
Innovation Solution
A method involving the preparation of a positive electrode active material for lithium secondary batteries by mixing transition metal hydroxides containing nickel, cobalt, and manganese with doping and coating elements like Al, Mg, and Zr, followed by calcination treatments to form a lithium composite transition metal oxide with a controlled weight ratio of doping to coating elements, enhancing structural and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiCoO2 is used as positive electrode active material, then charge-discharge efficiency and lifespan are improved, but high-temperature stability deteriorates and price increases
Solution Approach 1:
The patent uses LiCoO2 as the base material and forms composite structures with coating layers (such as Al2O3, Li2SiO3, or Li3PO4) on the particle surfaces. This composite approach maintains the excellent charge-discharge efficiency and lifespan of LiCoO2 while the coating layer provides thermal stability and prevents degradation at high temperatures.
Solution Approach 2:
The patent applies doping elements (such as Al, Mg, Ti, or Zr) at specific locations within the LiCoO2 crystal structure (substituting metal sites) and applies coating layers on the particle surfaces. This local modification approach preserves the bulk electrochemical performance while locally enhancing thermal stability where it is most needed (at the particle surfaces and critical crystal sites).
2Temperature
If LiMnO2 or LiMn2O4 is used as positive electrode active material, then thermal stability and price are improved, but capacity and conductivity deteriorate
Solution Approach 1:
The patent modifies the chemical composition parameters of LiMnO2 or LiMn2O4 by doping with elements such as Ni, Co, or Al at controlled concentrations (typically 1-10 mol%). This changes the electronic and ionic transport properties, thereby increasing conductivity and capacity while maintaining the inherent thermal stability of the manganese oxide structure.
Solution Approach 2:
The patent creates composite structures by combining LiMnO2 or LiMn2O4 with conductive additives (such as carbon materials) and/or coating layers. This composite approach enhances the conductivity and capacity of the manganese oxide while preserving its thermal stability.
3Quantity of substance
If LiNiO2 is used as positive electrode active material, then discharge capacity is improved, but structural stability deteriorates due to phase transition
Solution Approach 1:
The patent applies doping elements (such as Co, Mn, Al, or Ti) at specific metal sites within the LiNiO2 crystal structure to locally stabilize the lattice structure. This local structural reinforcement prevents the Jahn-Teller distortion and phase transitions that would otherwise occur during charge-discharge cycles, while maintaining the high discharge capacity of the nickel-rich composition.
Solution Approach 2:
The patent forms composite structures with coating layers (such as Al2O3, Li2SiO3, or Li3PO4) on the LiNiO2 particle surfaces. This composite approach protects the structurally vulnerable Ni-rich material from further degradation while preserving its high capacity characteristics.
4Duration of action of moving object
If lithium composite transition metal oxide with high nickel content is used, then cycle characteristics are improved, but thermal stability deteriorates due to reduced chemical stability
Solution Approach 1:
The patent creates composite structures by combining high-nickel lithium composite transition metal oxide with stable coating materials (such as Al2O3, Li2SiO3, Li3PO4, or TiO2) formed on the particle surfaces. This composite approach allows the high-nickel bulk material to provide excellent cycle characteristics while the thermally stable coating layer prevents thermal degradation and maintains chemical stability at elevated temperatures.
Solution Approach 2:
The patent applies doping elements (such as Co, Mn, Al, Ti, or Zr) at specific locations within the lithium composite transition metal oxide crystal structure to locally enhance structural stability. This local modification allows the material to maintain high nickel content for good cycle performance while having stabilized regions that resist thermal degradation.
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
This approach improves high-temperature lifetime characteristics, capacity, and thermal stability of lithium composite transition metal oxides, particularly those with high nickel content, resulting in enhanced cycle performance and durability.
Implementation Method 1
at least one doping element selected from the group consisting of Al, Mg, Co, V, Ti, Zr and W doped in the lithium composite transition metal oxide
Implementation Method 2
a coating layer containing the coating element is formed on the lithium composite transition metal oxide
Implementation Method 3
performing a first calcination treatment thereon to prepare a lithium composite transition metal oxide doped with the doping element
Data Source
AI summary
A method of preparing a positive electrode active material for a lithium secondary battery includes mixing a transition metal hydroxide containing transition metals including nickel (Ni), cobalt (Co) and manganese (Mn), a lithium-containing raw material and a doping raw material including at least one doping element selected from the group consisting of Al, Mg, Co, V, Ti, Zr and W and performing a first calcination treatment thereon to prepare a lithium composite transition metal oxide doped with the doping element; and mixing the lithium composite transition metal oxide and a coating raw material including at least one coating element selected from the group consisting of Al, Mg, Co, Ti, Zr and B and performing a second calcination treatment thereon to prepare a positive electrode active material in which a coating layer containing the coating element is formed on the lithium composite transition metal oxide.