Cathode Active Material Composition for High-Voltage Battery Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face significant challenges with the degradation of positive electrode active materials under high-temperature and high-voltage conditions, leading to reduced lifespan and safety issues due to surface instability, internal structural degradation, and increased interfacial resistance between the electrolyte and active material.
Innovation Solution
A lithium composite metal oxide particle structure represented by Li a Ni 1-x-y Co x M1 y M2 z M3 w O 2, where M1, M2, and M3 are specific metal elements with controlled surface energy distributions, forming a concentration gradient that enhances surface and internal stability, and a core-shell structure for improved thermal and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If LiNiO2 is used as a positive electrode active material to achieve high discharge capacity, then battery capacity is improved, but thermal stability and cycle characteristics deteriorate due to synthesis difficulty and structural instability
Solution Approach 1:
The patent applies local quality by creating a concentration gradient of metal elements within the active material particle. The composition varies from the surface to the center, with different regions having optimized elemental distributions to simultaneously achieve high capacity and stability. This is achieved through controlled coprecipitation processes that create non-uniform metal element distribution during particle formation.
Solution Approach 2:
The patent uses composite materials by combining multiple metal elements (Ni, Co, Mn, and other transition metals) in a single active material structure. This multi-element composite approach allows the material to exhibit both high discharge capacity from nickel-rich regions and enhanced thermal stability from cobalt and manganese components, resolving the contradiction between capacity and stability.
2Temperature
If LiMn2O4 is used as a positive electrode active material to achieve excellent thermal stability and low cost, then thermal stability is improved, but lifespan characteristic deteriorates due to structural deformation from Mn3+ Jahn-Teller distortion
Solution Approach 1:
The patent applies local quality by creating regions with different metal compositions within the particle structure. By controlling the concentration distribution of Mn and other metals, the patent creates stable regions that prevent Jahn-Teller distortion while maintaining thermal stability characteristics, thereby extending lifespan without sacrificing thermal performance.
Solution Approach 2:
The patent changes the compositional parameters by introducing additional transition metals and adjusting the Mn content and oxidation state through controlled coprecipitation. This parameter optimization prevents the formation of Mn3+ in sufficient quantities to cause Jahn-Teller distortion, while maintaining the thermal stability associated with lithium manganese oxide structures.
3Quantity of substance
If Li(NixCoymn z)O2 is used as a positive electrode active material to substitute for LiCoO2, then capacity is improved, but surface stability deteriorates leading to exothermic reactions and structural collapse under high temperature and voltage conditions
Solution Approach 1:
The patent applies local quality by creating a concentration gradient where the surface region has a different composition than the core. The surface is enriched with stabilizing elements through controlled coprecipitation, forming a protective layer that maintains surface stability under high temperature and voltage conditions while the interior maintains high capacity characteristics.
Solution Approach 2:
The patent applies preliminary action by pre-forming a stable surface composition during the coprecipitation process before the material is used in the battery. This preliminary structuring of the particle composition prevents subsequent surface degradation, exothermic reactions, and structural collapse during battery operation under harsh conditions.
Data Source
AI summary
The present invention provides a positive electrode active material for a secondary battery, the positive electrode active material including a lithium composite metal oxide particle represented by Formula 1 below, and a secondary battery including the same. [Formula 1] LiaNi1-x-yCoxM1yM2zM3wO2 In Formula 1, M1 is a metal element whose surface energy (ΔEsurf) calculated by Equation 1 below is -0.5 eV or higher, M2 is a metal element whose surface energy (ΔEsurf) calculated by Equation 1 below is -1.5 eV or higher and less than -0.5 eV, M3 is a metal element whose surface energy (ΔEsurf) calculated by Equation 1 below is less than -1.5 eV, and 1.0≤a≤1.5, 0<x≤0.5, 0<z≤0.05, 0.002≤w≤0.1, 0<x+y≤0.7. ΔEsurf=Esurf2−Esurf1=Eslab2−Ebulk−Eslab1−Ebulk In Equation 1 above, Esurf2 represents an extent to which a metal element is oriented toward the outermost surface of the lithium composite metal oxide particle, Esurf1 represents an extent to which the metal element is oriented toward a central portion of the lithium composite metal oxide particle, Eslab1 is energy of a slab model of the lithium composite metal oxide particle when the metal element is at the central portion of the lithium composite metal oxide particle, Eslab2 is energy of a slab model of the lithium composite metal oxide when the metal element is at the outermost surface of the lithium composite metal oxide, and Ebulk is energy of a bulk model corresponding to each of the slab models.