Mid-Ni Cathode Material with Controlled Particle Distribution
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Solution Overview
Problem
Existing lithium secondary batteries face challenges with high nickel content lithium transition metal oxides, leading to increased lithium impurities, stability issues, and cost, while reducing nickel content results in decreased electrochemical characteristics and capacity.
Innovation Solution
A positive electrode active material comprising a Mid-Ni type lithium transition metal oxide with controlled fine powder content and adjusted particle size distribution, characterized by specific nickel, cobalt, and manganese ratios, and particle forms, to improve stability and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nickel content in lithium transition metal oxide is increased to improve reversible capacity, then the discharge capacity is improved, but cation mixing increases and lithium impurities (LiOH, Li2CO3) accumulate on the surface
Solution Approach 1:
The patent optimizes the nickel content parameter to a specific range (0.6 ≤ x < 0.7 in Li1-yNixMn2-y-y/2-y/4O4) to balance reversible capacity with suppression of cation mixing and lithium impurity formation. This parameter optimization resolves the contradiction by finding the optimal point where capacity is sufficiently high while impurity generation is controlled.
Solution Approach 2:
The patent uses composite lithium transition metal oxide containing multiple elements (Li, Ni, Mn, and other transition metals) where each component contributes different properties. The composite structure allows high nickel content for capacity while other elements suppress cation mixing and reduce lithium impurity formation, resolving the contradiction between capacity and impurity generation.
2Quantity of substance
If the nickel content in lithium transition metal oxide is increased to improve reversible capacity, then the discharge capacity is improved, but the cost of raw materials increases
Solution Approach 1:
The patent optimizes the nickel content to a controlled range rather than using maximum nickel content, which reduces raw material cost while maintaining sufficient reversible capacity. This parameter optimization resolves the contradiction between capacity improvement and cost increase.
Solution Approach 2:
The patent substitutes expensive nickel with cheaper alternative transition metals in controlled amounts, reducing raw material cost while maintaining electrochemical performance through the composite structure.
3Object-generated harmful factors
If a washing process is performed to remove lithium impurities from the surface, then the lithium impurity content is reduced, but the surface of lithium transition metal oxide is damaged and lifetime degrades
Solution Approach 1:
The patent prevents lithium impurity formation in the first place by optimizing the synthesis conditions and composition, so that minimal or no washing process is needed. This preliminary prevention approach resolves the contradiction by eliminating the need for washing that would damage the surface.
Solution Approach 2:
The patent converts the potential harm of high nickel content (which causes lithium impurity formation) into a benefit by optimizing the composition and synthesis conditions to suppress impurity formation, making the washing process unnecessary and preserving the surface integrity.
4Object-generated harmful factors
If the nickel content is reduced to lower cost and reduce lithium impurities, then the cost and impurity content are improved, but the electrochemical characteristics and capacity decrease
Solution Approach 1:
The patent uses a composite lithium transition metal oxide where multiple elements work synergistically: nickel provides high capacity, while other transition metals suppress cation mixing and reduce lithium impurity formation. This composite approach resolves the contradiction by allowing reduced nickel content without sacrificing capacity.
Solution Approach 2:
The patent optimizes the composition parameters (ratios of different metals, oxygen content, particle size) to maximize electrochemical performance while using reduced nickel content, resolving the contradiction between impurity reduction and capacity maintenance.
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
Enhances lifetime characteristics and operational performance at high voltage by optimizing the nickel content and particle structure, balancing cost and electrochemical efficiency.
Implementation Method 1
a lithium secondary battery that stores electrical energy by the difference in chemical potential when lithium ions are intercalated/deintercalated into/from the positive electrode and the negative electrode
Implementation Method 2
Batteries store power by using materials capable of undergoing electrochemical reactions at a positive electrode and a negative electrode
Data Source
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AI summary
The present invention relates to a positive electrode active material and a lithium secondary battery comprising the same. More specifically, the present invention relates to a positive electrode active material comprising a lithium transition metal oxide of a Mid-Ni type having a relatively low nickel content, in which the content of fine powder in the positive electrode active material is controlled and the particle size distribution of the lithium transition metal oxide included in the positive electrode active material is adjusted, thereby improving capacity and lifetime characteristics and providing enhanced operational properties at high voltage.