Layered NCM Cathode Coating and Doping for High-Temperature Cycling
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Solution Overview
Problem
Lithium nickel cobalt manganese oxide-based lithium-ion secondary batteries exhibit low high-temperature cycling performance and high gas production during practical use.
Innovation Solution
A positive electrode active material with a lithium nickel cobalt manganese oxide matrix particle doped with elements M2 and M3, coated with an oxide of element M1, where M1, M2, and M3 are selected from specific elements, and the concentration of M3 decreases from the surface to the core, along with optional doping of element X, to enhance structural stability and reduce surface reactions.
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 to achieve high energy density, then theoretical capacity is improved, but high-temperature cycling performance deteriorates and gas production increases
Solution Approach 1:
The patent applies composite materials by combining lithium nickel cobalt manganese oxide with multiple doping elements (M2 and M3) and coating layers (oxide of M1). This creates a composite structure where the base material provides high capacity while the dopants and coating provide structural stability at high temperatures, resolving the contradiction between energy density and cycling performance.
Solution Approach 2:
The patent implements local quality by creating a concentration gradient of element M3 from the exterior surface to the core of the matrix particle, with relative deviation of local mass concentration of element M2 controlled at 20% or below. This non-uniform distribution optimizes different regions for different functions: the surface region provides stability and protects against gas production, while the core maintains high capacity, thus resolving the contradiction between energy density and high-temperature cycling performance.
2Use of energy by moving object
If lithium nickel cobalt manganese oxide is used as positive electrode active material to achieve high energy density, then theoretical capacity is improved, but gas production increases
Solution Approach 1:
The composite structure with doping elements and coating layers suppresses parasitic reactions between the electrolyte and the positive electrode material. The oxide coating layer of element M1 and the doped elements M2 and M3 create a stable interface that prevents gas-generating side reactions while maintaining the high capacity of the lithium nickel cobalt manganese oxide core, thus resolving the contradiction between energy density and gas production.
Solution Approach 2:
The patent applies preliminary anti-action by pre-coating the matrix particle surface with oxide of element M1 and doping with elements M2 and M3 before battery operation. This pre-established protective structure prevents harmful gas-producing reactions from occurring at the electrode-electrolyte interface during cycling, while the core material maintains its high energy density capability.
3Reliability
If uniform doping of element M2 is implemented to improve structural stability, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the relative deviation of local mass concentration of element M2 at 20% or below, and controlling the concentration gradient of element M3 from surface to core. These quantitative parameter specifications transform the complex doping process into a controllable manufacturing process with defined quality metrics, resolving the contradiction between structural stability and manufacturing complexity.
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 improves the high-temperature cycling performance, high-temperature storage performance, and reduces gas production, resulting in a lithium-ion secondary battery with high energy density.
Implementation Method 1
the matrix particle is doped with element M2 and element M3, relative deviation of a local mass concentration of element M2 in the matrix particle is 20% or below, and element M3 in the matrix particle has a decreasing concentration from the exterior surface to a core of the matrix particle
Implementation Method 2
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
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.