Positive Electrode Active Material with Charge Transport Channels
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Solution Overview
Problem
High-Ni-type lithium composite oxides used in lithium secondary batteries face issues with increased resistance and deteriorated lifetime characteristics as Ni content increases.
Innovation Solution
A positive electrode active material is developed with secondary particles that have a first concentration gradient section where the concentration of nickel, cobalt, and manganese increases, and a second concentration gradient section where the concentration decreases, forming a charge transport channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Ni content is increased to improve energy density and output characteristics, then capacity increases, but resistance characteristics deteriorate
Solution Approach 1:
The patent applies local quality by creating a concentration gradient structure where the surface region has different composition (higher Mn content) compared to the inner region (higher Ni content). This allows the surface to provide stability and lower resistance while the interior maintains high capacity, thus resolving the contradiction between energy density and resistance characteristics.
Solution Approach 2:
The patent uses composite materials by combining different metal elements (Ni, Co, Mn) in a gradient distribution within the same particle structure. The composite structure with varying local compositions enables simultaneous achievement of high energy density from Ni-rich interior and good resistance characteristics from Mn-rich surface.
2Productivity
If Ni content is increased to improve output characteristics, then discharge capacity increases, but lifetime characteristics deteriorate
Solution Approach 1:
The concentration gradient structure with Mn-enriched surface and Ni-enriched interior allows the surface to protect the high-capacity Ni core during cycling. The Mn-rich surface provides structural stability that extends lifetime while the Ni-rich interior delivers high discharge capacity, resolving the contradiction between productivity and duration.
3Ease of manufacture
If cation mixing between Li and transition metal increases, then synthesis becomes difficult, but rate characteristics improve
Solution Approach 1:
The patent changes the compositional parameters by creating a gradient structure where transition metal content varies from surface to interior. This parameter variation allows optimization of both synthesis ease (by controlling surface composition) and rate characteristics (by maintaining appropriate Ni content in interior), resolving the contradiction between ease of manufacture and speed.
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 formation of charge transport channels in the positive electrode active material improves resistance characteristics and enhances electrochemical performance, including lifetime and efficiency characteristics.
Implementation Method 1
a lithium secondary battery storing electrical energy due to a difference in chemical potential when lithium ions are intercalated/deintercalated into/from a positive electrode and a negative electrode
Implementation Method 2
materials facilitating an electrochemical reaction at a positive electrode and a negative electrode
Implementation Method 3
a first concentration gradient section in which a concentration of at least one selected from nickel, cobalt and manganese in the secondary particle increases and a second concentration gradient section in which the concentration decreases, along the circumferential surface of the secondary particle, thereby a charge transport channel may be formed in the positive electrode active material
Data Source
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AI summary
The present invention relates to a positive electrode active material and a lithium secondary battery using a positive electrode containing the positive electrode active material. More particularly, the present invention relates to a positive electrode active material that is able to solve a problem of increased resistance according to an increase in Ni content by forming a charge transport channel in a lithium composite oxide and a lithium secondary battery using a positive electrode containing the positive electrode active material.