Positive electrode active material and lithium secondary battery comprising the same
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Solution Overview
Problem
High-Ni lithium composite oxides used in lithium secondary batteries face issues with increased resistance and structural instability due to insufficient lithium ion and charge diffusion, leading to reduced lifetime and capacity, particularly as the Ni content increases.
Innovation Solution
A positive electrode active material is developed with primary particles that have regions of different transition metal concentrations, enhancing lithium ion and charge diffusion efficiency and structural stability by forming a secondary particle structure with varying concentrations of Ni, Co, Mn, and Al, and incorporating a coating layer to improve electrochemical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the Ni content in lithium composite oxide is increased to improve energy density and discharge capacity, then the battery characteristic such as high discharge capacity is improved, but the resistance characteristics deteriorate and lifetime characteristics are reduced
Solution Approach 1:
The patent applies local quality by creating a concentration gradient of transition metals within the lithium composite oxide particle. The particle contains a first region with a first concentration of transition metal and a second region with a second concentration different from the first, allowing different zones to have optimized properties for capacity and resistance respectively
Solution Approach 2:
The patent changes the concentration parameter of transition metals spatially within the particle. By varying the transition metal concentration from one region to another, the patent optimizes both the discharge capacity (in high-Ni regions) and resistance characteristics (in regions with different transition metal content) simultaneously
2Quantity of substance
If the Ni content in lithium composite oxide is increased to improve energy density, then the reversible capacity is improved, but the structural stability deteriorates
Solution Approach 1:
The patent creates regions with different transition metal concentrations within the particle, where certain regions have higher Ni content for capacity while other regions have different compositions that provide structural stability, preventing crystal structure collapse during charging/discharging
Solution Approach 2:
The patent creates a composite structure within the single particle by having regions with different transition metal compositions. This internal composite structure allows the particle to simultaneously achieve high reversible capacity from Ni-rich regions and structural stability from regions with different transition metal content
3Quantity of substance
If the Ni content in lithium composite oxide is increased to improve discharge capacity, then the energy density is improved, but the diffusion efficiency of lithium ions deteriorates
Solution Approach 1:
The patent creates regions with different transition metal concentrations that facilitate lithium ion diffusion. By having zones with optimized composition, the patent maintains high discharge capacity while improving the diffusion efficiency of lithium ions through the particle structure
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 solution improves the diffusion efficiency of lithium ions and charges, enhances structural stability, and extends the lifetime of lithium secondary batteries by mitigating resistance increases and maintaining high capacity, even with higher Ni content.
Implementation Method 1
a lithium secondary battery storing electrical energy by means of a difference in chemical potential when lithium ions are intercalated/deintercalated into/from a positive electrode and a negative electrode
Implementation Method 2
Batteries store electrical power by using materials facilitating an electrochemical reaction at a positive electrode and a negative electrode
Implementation Method 3
the higher the Ni content, the larger the resistance, and thus the lifetime deteriorates. Likewise, as the Ni content in the lithium composite oxide increases, it is believed that one of the causes of the increase in resistance is insufficient diffusion of lithium ions and/or charges in the lithium composite oxide
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 including the same. More particularly, the present invention relates to a positive electrode active material that has increased efficiency in the diffusion of lithium ions and/or charges and increased structural stability by locally forming regions with different concentrations of an arbitrary transition metal in a primary particle, and a lithium secondary battery using a positive electrode including the same.