Lithium Nickel Composite Oxide Surface Coating for Battery Stability
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Solution Overview
Problem
Current lithium-nickel composite oxides for non-aqueous electrolyte secondary batteries face challenges in achieving high electric capacity, high output, and high thermal stability, with existing materials either compromising on capacity or stability due to limitations in nickel content and crystal structure.
Innovation Solution
A lithium-nickel composite oxide with increased nickel content and a specific crystal structure, where tungsten and lithium form a fine particle on the surface of primary particles, is produced by mixing nickel and lithium compounds, calcining, washing, and heat-treating to enhance electric capacity and output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If nickel content in lithium-nickel composite oxide is increased to improve electric capacity and output, then charge and discharge capacity increases, but thermal stability deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the interior contains high-nickel lithium-nickel composite oxide (Li1-a-bNiaCobM1-yO2) for high capacity, while the surface is covered with a lithium phosphate-containing coating layer for thermal stability. This allows different regions of the particle to have different compositions optimized for their specific functions.
Solution Approach 2:
The patent uses composite materials by combining lithium-nickel composite oxide with lithium phosphate to form a coated composite structure. The coating layer contains lithium phosphate and optionally other phosphates, creating a composite material that exhibits both the high capacity of nickel-rich oxide and the thermal stability of phosphate compounds.
2Quantity of substance
If nickel content is increased to achieve high energy density, then battery energy density improves, but crystal structure stability under charging condition deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the interior contains high-nickel lithium-nickel composite oxide (Li1-a-bNiaCobM1-yO2) for high capacity, while the surface is covered with a lithium phosphate-containing coating layer for thermal stability. This allows different regions of the particle to have different compositions optimized for their specific functions.
Solution Approach 2:
The patent uses composite materials by combining lithium-nickel composite oxide with lithium phosphate to form a coated composite structure. The coating layer contains lithium phosphate and optionally other phosphates, creating a composite material that exhibits both the high capacity of nickel-rich oxide and the thermal stability of phosphate compounds.
3Reliability
If element substitution is performed to improve thermal stability, then thermal stability improves, but electric capacity decreases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the interior contains high-nickel lithium-nickel composite oxide (Li1-a-bNiaCobM1-yO2) for high capacity, while the surface is covered with a lithium phosphate-containing coating layer for thermal stability. This allows different regions of the particle to have different compositions optimized for their specific functions.
Solution Approach 2:
The patent uses composite materials by combining lithium-nickel composite oxide with lithium phosphate to form a coated composite structure. The coating layer contains lithium phosphate and optionally other phosphates, creating a composite material that exhibits both the high capacity of nickel-rich oxide and the thermal stability of phosphate compounds.
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 positive electrode active material with improved electric capacity, output, and thermal stability, allowing for the production of batteries with high energy density and extended cycle life.
Implementation Method 1
mixing a nickel compound with a lithium compound, and calcining the resulting mixture
Implementation Method 2
calcining the resulting mixture in an oxygen atmosphere
Implementation Method 3
heat-treating the resulting mixture to form a fine particle containing W and Li on the surface
Data Source
AI summary
A positive electrode active material for a non-aqueous electrolyte secondary battery, including primary particles of a lithium nickel composite oxide represented by the formula: LibNi1-x-yCoxMyO2 wherein M represents at least one element selected from Mg, Al, Ca, Ti, V, Cr, Mn, Nb, Zr and Mo; b represents a number satisfying 0.95≤b≤1.03; and x represents a number satisfying 0<x≤0.15 and y represents a number satisfying 0<y≤0.07, wherein the sum total of x and y is 0.16 or smaller, i.e., x+y≤0.16) and secondary particles that are aggregates of the primary particles, wherein microparticles containing W and Li are present on the surface of each of the primary particles, and the length of axis-c of the lithium nickel composite oxide is 14.183 angstroms or more as determined by a Rietveld analysis of X-ray diffraction data on the oxide.