NCM Cathode Material Coating and Gradient Doping for Low Gas Generation
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Solution Overview
Problem
Lithium-ion secondary batteries using lithium nickel cobalt manganese oxides as positive electrode active materials exhibit low high-temperature cycling performance and generate excessive gas during practical use.
Innovation Solution
A positive electrode active material is developed, comprising matrix particles doped with elements M2 and M3, where M2 has a uniform distribution and M3 has a decreasing concentration from the surface to the core, coated with an oxide layer of element M1. Elements M1, M2, and M3 are selected from specific elements such as Mg, Al, Ca, Ba, Ti, Zr, Zn, B, Si, Ti, Cr, Mo, V, Ge, Se, Zr, Nb, Ru, Rh, Pd, Sb, Te, Ce, and W.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium nickel cobalt manganese oxide is used as positive electrode active material, then high energy density is achieved, but high-temperature cycling performance deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core contains lithium nickel cobalt manganese oxide for high capacity, while the shell contains lithium nickel cobalt aluminum manganese oxide providing structural stability. This spatial differentiation of material properties resolves the contradiction between energy density and high-temperature cycling performance.
Solution Approach 2:
The patent uses composite materials by combining lithium nickel cobalt manganese oxide with lithium nickel cobalt aluminum manganese oxide to form a composite positive electrode active material. This composite structure integrates the high capacity advantage of the former with the thermal stability advantage of the latter, simultaneously achieving high energy density and reliable high-temperature cycling performance.
2Use of energy by moving object
If lithium nickel cobalt manganese oxide is used as positive electrode active material, then high energy density is achieved, but gas production increases
Solution Approach 1:
The patent applies local quality by concentrating the high-capacity lithium nickel cobalt manganese oxide in the core region while placing the gas-suppressing lithium nickel cobalt aluminum manganese oxide in the shell region. This spatial arrangement allows the material to achieve high energy density while the aluminum-containing shell prevents gas generation during cycling.
Solution Approach 2:
The patent uses composite materials to combine the high capacity of lithium nickel cobalt manganese oxide with the low gas-production characteristic of lithium nickel cobalt aluminum manganese oxide. The composite structure enables the positive electrode active material to deliver high energy density while suppressing harmful gas production through the protective effect of the aluminum-containing phase.
3Reliability
If element M3 is doped uniformly throughout the matrix particle, then structural stability is improved, but surface reactivity with electrolyte increases
Solution Approach 1:
The patent applies local quality by creating a concentration gradient of element M3 where the concentration decreases from the surface toward the core of the matrix particle. This gradient structure provides structural stability through bulk doping while reducing surface reactivity by having lower M3 concentration at the surface, thereby minimizing side reactions with the electrolyte.
Solution Approach 2:
The patent uses parameter changes by varying the concentration of element M3 as a function of position within the matrix particle. The concentration parameter is optimized to decrease from surface to core, creating a gradient that simultaneously achieves structural stability and reduced surface reactivity, resolving the contradiction between these two requirements.
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 positive electrode active material enhances the high-temperature cycling and storage performance of lithium-ion secondary batteries, reduces gas production, and maintains high energy density.
Implementation Method 1
the matrix particle is doped with element M2 and element M3
Implementation Method 2
a coating layer covering an exterior surface of the matrix particle, where the coating layer includes an oxide of element M1
Implementation Method 3
element M3 in the matrix particle has a decreasing concentration from the exterior surface to a core of the matrix particle
Implementation Method 4
the matrix particle is uniformly doped with element M2, the relative deviation of a local mass concentration of element M2 in the matrix particle is 20% or below
Data Source
AI summary
A positive electrode active material and a preparation method thereof, a positive electrode plate, a lithium-ion secondary battery, and a battery module, battery pack, and apparatus containing such lithium-ion secondary battery are provided. The positive electrode active material includes matrix particles and a coating layer covering an exterior surface of the matrix particle, where the matrix particle includes a lithium nickel cobalt manganese oxide, and the coating layer includes an oxide of element M1; the matrix particle is doped with element M2 and element M3, element M2 in the matrix particle is uniformly distributed, and element M3 in the matrix particle has a decreasing concentration from the exterior surface to a core of the matrix particle; and element M1 and element M3 are each independently selected from one or more of Mg, Al, Ca, Ba, Ti, Zr, Zn, and B, and element M2 includes one or more of Si, Ti, Cr, Mo, V, Ge, Se, Zr, Nb, Ru, Rh, Pd, Sb, Te, Ce, and W.