Titanium-Doped Cathode Coating for High-Temperature Li-Ion Output
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in achieving high output efficiency and maintaining high-temperature lifetime characteristics due to limitations in positive electrode active materials, such as cobalt-based materials being expensive and nickel-based materials experiencing cation mixing issues.
Innovation Solution
A positive electrode active material is developed using a lithium composite oxide that includes nickel and titanium, where titanium is present both doped within the oxide and in an oxide form on the surface, optimizing the electrochemical properties and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiCoO2 is used as positive electrode active material, then lifetime characteristics and charge/discharge efficiency are improved, but cost increases due to limited cobalt resources
Solution Approach 1:
The patent changes the chemical composition parameters by reducing cobalt content and increasing nickel content in the lithium composite oxide (e.g., LiNi0.8Co0.1Mn0.1O2), while adjusting the oxidation states of metals to maintain structural stability and electrochemical performance, thereby reducing cost while preserving reliability
Solution Approach 2:
The patent uses composite materials by combining multiple transition metals (Ni, Co, Mn) in specific ratios within the lithium composite oxide structure, and further composite coating with titanium oxide and aluminum oxide to achieve both cost reduction and maintained performance
2Ease of manufacture
If LiMnO2 or LiMn2O4 is used as positive electrode active material, then thermal safety and cost are improved, but capacity and high-temperature characteristics deteriorate
Solution Approach 1:
The patent changes the metal composition parameters by using high nickel content (0.6-0.95) in the lithium composite oxide, which significantly increases capacity while maintaining thermal stability through controlled oxidation states and composite coating structures
3Quantity of substance
If LiNiO2-based positive electrode active material is used, then discharge capacity is improved, but rate characteristics deteriorate due to cation mixing between Li and transition metal
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core contains the high-capacity lithium nickel oxide and the outer shell contains titanium oxide coating, which prevents cation mixing at the surface while maintaining high capacity, thereby improving rate characteristics
Solution Approach 2:
The patent applies preliminary anti-action by pre-coating the lithium nickel oxide surface with titanium oxide and aluminum oxide before electrode fabrication, which prevents cation mixing between Li and Ni from occurring during battery operation, thereby maintaining both high capacity and good rate characteristics
4Quantity of substance
If high-Ni type positive electrode active material is used, then energy capacity is improved, but stability deteriorates due to cation mixing issues
Solution Approach 1:
The patent changes the oxidation state parameters by controlling the average oxidation state of transition metals to be +3.6 to +4.0, and specifically setting Ni oxidation state to +3.8 to +4.0, which stabilizes the crystal structure while maintaining high energy capacity
Solution Approach 2:
The patent uses composite materials by coating the high-Ni lithium composite oxide with titanium oxide and aluminum oxide layers, which prevent cation mixing and structural degradation, thereby maintaining both high energy capacity and stability during cycling
5Power
If titanium is doped in lithium composite oxide, then output efficiency is improved, but high-temperature lifetime characteristics may deteriorate without surface oxide coating
Solution Approach 1:
The patent applies local quality by concentrating titanium in the surface region (0-0.05r from surface) at higher levels (1.5-5 times) than the center region, which provides surface stability for high-temperature lifetime while maintaining bulk properties for output efficiency
Solution Approach 2:
The patent uses composite materials by combining titanium doping in the bulk with titanium oxide coating on the surface, creating a multi-layer composite structure that simultaneously provides both output efficiency and high-temperature stability
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 simultaneously enhances the output efficiency and high-temperature cycle capacity retention rate of lithium secondary batteries, improving overall electrochemical performance and extending battery lifespan.
Implementation Method 1
the titanium is doped in the lithium composite oxide
Implementation Method 2
the titanium is present in an oxide form in at least a portion of the surface of the lithium composite oxide
Implementation Method 3
when lithium ions are intercalated/deintercalated into/from a positive electrode and a negative electrode
Data Source
Figure 1~2
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AI summary
The present invention relates to a positive electrode active material and a lithium secondary battery comprising the same, and more specifically, to a positive electrode active material including a lithium composite oxide containing at least nickel and titanium, wherein the titanium is present in an oxide form in at least a portion of the surface of the lithium composite oxide at the same time as being doped in the lithium composite oxide, and thus it is possible to simultaneously improve the output efficiency and high-temperature lifetime characteristics (high-temperature cycle capacity retention rate) of a lithium secondary battery using the positive electrode active material, and a lithium secondary battery including the same.