Cathode active material for lithium secondary battery and lithium secondary battery including the same
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face challenges with low ionic conductivity in lithium metal phosphate cathode active materials, which degrade power properties and require enhanced energy density and lifespan, especially at low temperatures.
Innovation Solution
A cathode active material is developed with composite particles of lithium metal phosphate coated with carbon, where the carbon coating thickness is uniformly controlled to 15 nm or less, improving electrical conductivity and power properties, and includes a method of mixing a lithium source, metal phosphate, and carbon source, followed by calcination to form a uniformly coated material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal phosphate is used as cathode active material, then high operational voltage and energy density are achieved, but low ionic conductivity degrades power property
Solution Approach 1:
The patent uses a composite structure where lithium metal phosphate particles are coated with carbon material to form a composite cathode active material. The carbon coating layer (0.1-5 nm thickness) provides high electrical conductivity while the lithium metal phosphate core maintains high energy density, resolving the contradiction between energy density and power property
Solution Approach 2:
The patent controls the thickness of the carbon coating layer within a specific range (0.1-5 nm) and maintains uniform distribution on particle surfaces. By optimizing these parameters, the material achieves both high electrical conductivity (improving power property) and high energy density (from the lithium metal phosphate core)
2Reliability
If carbon coating is applied to improve electrical conductivity, then power property is enhanced, but manufacturing precision is required to control uniform thickness
Solution Approach 1:
The carbon material is mixed with lithium metal phosphate particles before calcination, allowing the carbon to be uniformly distributed and form a controlled coating layer during the heating process. This preliminary mixing approach ensures uniform coating thickness without requiring complex post-coating processes
Solution Approach 2:
The patent specifies precise parameters for carbon coating thickness (0.1-5 nm) and controls the calcination conditions (temperature, time, atmosphere) to achieve uniform coating. By optimizing these parameters, the manufacturing process achieves both uniform coating and high power property
3Use of energy by moving object
If higher capacity and energy density are pursued, then battery performance is improved, but low-temperature performance degrades
Solution Approach 1:
The carbon-coated lithium metal phosphate composite structure provides high electrical conductivity through the carbon layer, which facilitates ion and electron transport even at low temperatures. This allows the battery to maintain high capacity while improving low-temperature performance
Solution Approach 2:
The uniform carbon coating with controlled thickness (0.1-5 nm) modifies the surface properties of lithium metal phosphate particles, reducing resistance to ion diffusion and improving electrochemical activity at low temperatures while maintaining 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 carbon-coated lithium metal phosphate particles enhance the electrical conductivity and low-temperature performance of lithium secondary batteries, improving power properties and capacity retention while maintaining stability and cost efficiency.
Implementation Method 1
The carbon coating formed on at least a portion of a surface of the lithium metal phosphate particle enhances electrical conductivity
Implementation Method 2
etching a surface of the composite particle using an argon ion gun of the XPS
Data Source
Figure 1~2
Figure 3
AI summary
A cathode active material for a lithium secondary battery according to an embodiment of the present disclosure a plurality of composite particles, each of which comprises a lithium metal phosphate particle, and a carbon coating formed on at least a portion of a surface of the lithium metal phosphate particle. A standard deviation of thickness values of the carbon coating measured by an X-ray photoelectron spectroscopy (XPS) for five different composite particles of the plurality of composite particles is 15 nm or less.