Nickel-Rich Cathode Material Surface Control for Lower Resistance
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Solution Overview
Problem
Existing secondary batteries have insufficient battery characteristics, necessitating the development of improved positive electrode active materials to enhance performance.
Innovation Solution
A secondary battery-use positive electrode active material is developed, comprising a layered rock salt-type compound with a composition of nickel, cobalt, and aluminum, where the nickel content is 87 mol% or more, and the cobalt and aluminum contents are within specific ranges. This active material is analyzed using X-ray photoelectron spectroscopy to ensure a concentration ratio of 1.60 or less and an intensity ratio of 0.39 or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a positive electrode active material containing high nickel content is used to increase energy density, then battery capacity is improved, but charge transfer resistance increases and battery characteristics deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core contains high nickel content (87-100 mol%) for high capacity, while the outer shell contains different composition (with cobalt 0-11 mol% and aluminum 0-8 mol%) for improved charge transfer. This spatial differentiation of composition allows simultaneous achievement of high capacity and good charge transfer characteristics.
Solution Approach 2:
The patent uses composite materials by combining nickel-rich layered rock salt-type compound with cobalt and aluminum-containing compounds to form a composite positive electrode active material. This composite structure leverages the high capacity of nickel while utilizing cobalt and aluminum to improve charge transfer resistance and overall battery characteristics.
2Ease of manufacture
If conventional positive electrode active materials are used, then manufacturing process is simple, but battery characteristics are insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the compositional parameters of the positive electrode active material: nickel content (87-100 mol%), cobalt content (0-11 mol%), aluminum content (0-8 mol%), and the concentration ratio RX (≤1.60). By optimizing these parameters, the patent achieves improved battery characteristics while maintaining a manufacturing process that is substantially similar to conventional methods.
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 proposed positive electrode active material achieves excellent battery characteristics, including reduced charge transfer resistance and minimized gas generation, thereby improving the overall performance of secondary batteries.
Implementation Method 1
In surface analysis using X-ray photoelectron spectroscopy, a concentration ratio represented by Formula (1) is 1.60 or less and an intensity ratio represented by Formula (2) is 0.39 or less
Data Source
AI summary
A secondary battery includes a positive electrode containing a positive electrode active material, a negative electrode, and an electrolytic solution. The positive electrode active material contains a layered rock salt-type compound, and the layered rock salt-type compound contains nickel, cobalt, and aluminum as constituent elements. When a sum of contents of nickel, cobalt, and aluminum in the layered rock salt-type compound is regarded as 100 parts by mol, a content of the nickel is 87 parts by mol or more and 100 parts by mol or less, a content of the cobalt is 0 parts by mol or more and 11 parts by mol or less, and a content of the aluminum is 0 parts by mol or more and 8 parts by mol or less. In surface analysis of the positive electrode active material using X-ray photoelectron spectroscopy, a concentration ratio represented by Formula (1) is 1.60 or less and an intensity ratio represented by Formula (2) is 0.39 or less:RX=X2/X1(1)where RX is a concentration ratio, X1 is a sum (atom %) of a concentration (atom %) of nickel calculated based on a Ni2p3/2 spectrum, a concentration (atom %) of cobalt calculated based on a Co2p3/2 spectrum, and a concentration (atom %) of aluminum calculated based on an A12s spectrum, and X2 is a concentration (atom %) of a carbonate calculated based on a C1s spectrum,RY=Y2/Y1(2)where RY is an intensity ratio, Y1 is a peak intensity of the Ni2p3/2 spectrum, and Y2 is a peak intensity of a satellite spectrum derived from the Ni2p3/2 spectrum.