Dual-Coated Cathode Active Material for Capacity and Low DC-IR
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Solution Overview
Problem
Existing high-Ni multi-particle cathode materials suffer from low life characteristics and low capacity, while small-particle-diameter single-particle cathode materials have high DC-IR resistance and efficiency issues.
Innovation Solution
A cathode active material comprising large-particle-diameter lithium metal oxide with a boron coating and small-particle-diameter lithium metal oxide with a cobalt coating, mixed in specific ratios, to achieve a DC-IR resistance value within a defined range, enhancing electrochemical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If large-particle-diameter cathode material is used, then capacity is improved, but life characteristic deteriorates
Solution Approach 1:
The patent applies local quality by coating only the surface of large-particle-diameter cathode material with aluminum oxide. This creates a protective layer on the surface while maintaining the bulk properties of the large particles, thereby improving life characteristic without sacrificing capacity
Solution Approach 2:
The patent creates a composite structure by combining large-particle-diameter cathode material with an aluminum oxide coating layer. This composite approach allows the material to benefit from both the high capacity of large particles and the stability/protection provided by the aluminum oxide layer, improving life characteristic
2Reliability
If small-particle-diameter cathode material is used, then life characteristic is improved, but DC-IR resistance increases
Solution Approach 1:
The patent applies local quality by selectively coating the surface of small-particle-diameter cathode material with aluminum oxide. This protective coating reduces DC-IR resistance at the particle surface while maintaining the life characteristic benefits of small particle size
Solution Approach 2:
The aluminum oxide coating acts as an intermediary layer between the small-particle-diameter cathode material and the electrolyte. This intermediate layer modifies the surface properties to reduce DC-IR resistance while allowing the small particle size to maintain good life characteristics
3Quantity of substance
If high-nickel-based cathode material is used, then capacity is improved, but gas generation increases
Solution Approach 1:
The patent converts the harmful effect of high-nickel-based cathode material (gas generation) into a benefit by coating it with aluminum oxide. The coating layer suppresses gas generation while allowing the high-nickel material to maintain its high capacity
Solution Approach 2:
The patent applies local quality by coating only the surface of high-nickel-based cathode material with aluminum oxide. This localized treatment suppresses gas generation at the particle surface where electrochemical reactions occur, while maintaining the bulk high-nickel composition for high capacity
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 cathode active material improves discharging capacity, life, and initial DC-IR resistance characteristics by controlling the content of boron and cobalt coatings, resulting in a more efficient lithium secondary battery.
Implementation Method 1
a coating layer disposed on the large-particle-diameter lithium metal oxide and including 1.0 to 7.0 wt% of boron
Implementation Method 2
a coating layer disposed on the small-particle-diameter lithium metal oxide and including 3.0 to 12.0 wt% of cobalt
Implementation Method 3
manufacturing a first cathode active material by mixing and heat-treating large-particle-diameter lithium metal oxide and a boron raw material
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A cathode active material for a lithium secondary battery according to an embodiment of the present disclosure includes a first cathode active material and a second cathode active material having different average particle diameters. The first cathode active material includes large-particle-diameter lithium metal oxide and a coating layer disposed on the large-particle-diameter lithium metal oxide and including 1.0 to 7.0 wt% of boron, and the second cathode active material includes small-particle-diameter lithium metal oxide and a coating layer disposed on the small-particle-diameter lithium metal oxide and including 3.0 to 12.0 wt% of cobalt.