Niobium-Modified Lithium-Nickel-Manganese Cathode for Thermal Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face challenges in achieving both high battery capacity and thermal stability, particularly during overcharging, while also requiring simplified industrial-scale production processes.
Innovation Solution
A positive electrode active material comprising a lithium-nickel-manganese composite oxide with a specific amount of niobium, where niobium is solid-solved in primary particles and present as a lithium-niobium compound on the surfaces, is used, along with a method involving a niobium mixing process and firing in an oxidizing atmosphere to enhance thermal stability and battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heterogeneous elements or oxide coatings are added to stabilize crystal structure and improve thermal stability, then thermal stability is improved, but initial battery capacity significantly reduces
Solution Approach 1:
The invention changes the chemical composition parameters by incorporating niobium at specific concentrations (0.01≤z≤0.05 in the formula) and controlling the Li/Nb ratio within 1:9 to 1:1, achieving optimal balance between thermal stability and battery capacity. This parameter optimization resolves the contradiction by finding the precise compositional window where both requirements are satisfied.
Solution Approach 2:
The invention creates a composite material system combining lithium-nickel-cobalt-manganese composite oxide with niobium compounds, where niobium serves dual functions: stabilizing the crystal structure (improving thermal stability) and maintaining electrochemical performance (preserving battery capacity). The composite structure with controlled niobium distribution achieves both contradictory requirements simultaneously.
2Reliability
If complex production methods are used to improve thermal stability and battery capacity, then performance is improved, but production processes become complicated and industrial scale production becomes difficult
Solution Approach 1:
The invention merges the functions of crystal structure stabilization and capacity enhancement into a single niobium addition step. By incorporating niobium during the primary synthesis process rather than through separate coating or treatment steps, the method simplifies production while achieving both thermal stability and high capacity. The unified approach reduces process complexity for industrial scale production.
Solution Approach 2:
The invention establishes specific parameter ranges for niobium content (0.01≤z≤0.05) and Li/Nb ratio (1:9 to 1:1) that optimize both performance and manufacturability. These parameter specifications enable consistent quality control and facilitate industrial scale production by providing clear manufacturing guidelines, resolving the contradiction between performance improvement and ease of manufacture.
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 approach results in a nonaqueous electrolyte secondary battery with high battery capacity, durability, and thermal stability, while allowing for easy industrial-scale production, effectively inhibiting oxygen release during overcharging.
Implementation Method 1
niobium is solid-solved in primary particles and present as a lithium-niobium compound on the surfaces
Implementation Method 2
coats the surface of the positive electrode active material with an oxide such as SiO2, Al2O3, or ZrO2... a lithium-niobium compound... present as a lithium-niobium compound on the surfaces
Implementation Method 3
a method involving a niobium mixing process and firing in an oxidizing atmosphere to enhance thermal stability and battery performance
Data Source
AI summary
A positive electrode active material for a nonaqueous electrolyte secondary battery is disclosed which contains a lithium-nickel-manganese composite oxide containing a secondary particle formed of a plurality of flocculated primary particles and a lithium-niobium compound. The positive electrode active material is represented by General Formula (1): LidNi1−a−b−cMnaMbNbcO2+γ (M is at least one element selected from Co, W, Mo, V, Mg, Ca, Al, Ti, Cr, Zr, and Ta; and 0.03≤a≤0.60, 0≤b≤0.60, 0.02≤c≤0.08, a+b+c<1, 0.95≤d≤1.20, and 0≤γ≤0.5, the lithium-nickel-manganese composite oxide has a (003)-plane crystallite diameter of at least 50 nm and up to 130 nm, the lithium-niobium compound is present on surfaces of the primary particles, and part of niobium in the positive electrode active material is solid-solved in the primary particles.