Niobium-Doped Li-Ni-Mn Oxide Core-Shell Cathode for Thermal Safety
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face challenges in achieving both high energy density, output characteristics, and thermal stability, particularly during short circuits, where high conductivity typically enhances charging/discharging capacity but complicates thermal safety.
Innovation Solution
A positive electrode active material comprising a lithium-nickel-manganese composite oxide with solid-solved niobium, specifically formulated to reduce conductivity and enhance thermal stability, is developed, incorporating a niobium mixing process and firing in an oxidative atmosphere to create a polycrystalline structure with controlled niobium distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high conductivity positive electrode active material is used, then charging/discharging capacity and output characteristics are improved, but thermal stability during short circuits deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the central core region contains high nickel content (Ni≥0.5) for high capacity and conductivity, while the peripheral shell region contains lower nickel content (Ni<0.5) and higher manganese content for thermal stability. This spatial differentiation of composition allows simultaneous optimization of both power output and thermal safety properties in different regions of the same particle.
Solution Approach 2:
The patent employs composite materials by combining nickel-rich and manganese-rich phases within a single particle structure. The nickel-rich core provides high electrical conductivity and capacity, while the manganese-rich shell provides thermal stability and structural integrity during short circuits. This composite approach resolves the contradiction by integrating materials with complementary properties into a unified structure.
2Quantity of substance
If nickel content is increased for high capacity, then energy density is improved, but thermal stability deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the central core region contains high nickel content (Ni≥0.5) for high capacity and conductivity, while the peripheral shell region contains lower nickel content (Ni<0.5) and higher manganese content for thermal stability. This spatial differentiation of composition allows simultaneous optimization of both power output and thermal safety properties in different regions of the same particle.
Solution Approach 2:
The patent employs composite materials by combining nickel-rich and manganese-rich phases within a single particle structure. The nickel-rich core provides high electrical conductivity and capacity, while the manganese-rich shell provides thermal stability and structural integrity during short circuits. This composite approach resolves the contradiction by integrating materials with complementary properties into a unified structure.
3Object-affected harmful factors
If conductivity is reduced for thermal safety, then thermal stability during short circuits is improved, but output characteristics deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the central core region contains high nickel content (Ni≥0.5) for high capacity and conductivity, while the peripheral shell region contains lower nickel content (Ni<0.5) and higher manganese content for thermal stability. This spatial differentiation of composition allows simultaneous optimization of both power output and thermal safety properties in different regions of the same particle.
Solution Approach 2:
The patent employs composite materials by combining nickel-rich and manganese-rich phases within a single particle structure. The nickel-rich core provides high electrical conductivity and capacity, while the manganese-rich shell provides thermal stability and structural integrity during short circuits. This composite approach resolves the contradiction by integrating materials with complementary properties into a unified 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 achieves both high energy density and output characteristics while ensuring thermal stability during short circuits by reducing conductivity, thereby inhibiting abrupt current increases and improving safety.
Implementation Method 1
containing a secondary particle formed of a plurality of flocculated primary particles, in which the lithium-nickel-manganese composite oxide is represented by a general formula: LidNi1-a-b-cMnaMbNbcO2+γ (in the general formula, M is at least one element selected from Co, W, Mo, V, Mg, Ca, Al, Ti, Cr, Zr, and Ta; and 0.05≤a≤0.60, 0≤b≤0.60, 0.0003≤c≤0.03, 0.95≤d≤1.20, and 0≤γ≤0.5), at least part of niobium is solid-solved in the primary particles
Implementation Method 2
a method including a mixing process of mixing a nickel-containing hydroxide, a lithium compound, and a niobium compound with an average particle diameter of 0.1 to 10 μm to obtain a lithium mixture and a firing process of firing the lithium mixture in an oxidative atmosphere at 700 to 840° C. to obtain the lithium-transition metal composite oxide
Implementation Method 3
a mixing process of mixing a nickel-containing hydroxide, a lithium compound, and a niobium compound with an average particle diameter of 0.1 to 10 μm to obtain a lithium mixture
Data Source
AI summary
Provided is a positive electrode active material with which a nonaqueous electrolyte secondary battery can be obtained that achieves both high energy density and output characteristics and thermal stability at the time of short-circuit owing to low conductivity. A positive electrode active material for a nonaqueous electrolyte secondary battery contains a lithium-nickel-manganese composite oxide containing a secondary particle formed of a plurality of flocculated primary particles. The lithium-nickel-manganese composite oxide is represented by General Formula (1): LidNi1-a-b-cMnaMbNbcO2+γ, at least part of niobium is solid-solved in the primary particles, and a maximum niobium concentration within the primary particles is at least one time and up to three times an average niobium concentration within the primary particles.