Doped NCM Single-Particle Cathodes for High-Voltage Cycle Life
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Solution Overview
Problem
Lithium nickel cobalt manganese oxide (NCM) positive electrode active materials for lithium secondary batteries exhibit inferior performance and rapid deterioration when used at high voltages due to higher lithium deintercalation and instability at high state of charge, necessitating the development of materials with improved lifetime characteristics.
Innovation Solution
A nickel-based lithium composite metal oxide single particle with specific metal doping and surface coating, calcined at high temperatures to achieve crystal grains of 180 nm to 300 nm, enhancing stability and reactivity, is used as a positive electrode active material, along with a method involving multiple calcination steps to control metal content and crystal structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If NCM positive electrode active material is used at high voltage (4.35 V or more), then energy density and voltage are improved, but lifetime characteristic deteriorates rapidly due to higher lithium deintercalation and instability at high state of charge
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crystal grain size of NCM particles to 180-300 nm and doping metals at specific concentrations (2500-6000 ppm). These parameter modifications optimize the material's electrochemical properties, enabling stable operation at high voltages while maintaining long cycle life, thus resolving the contradiction between power and reliability
Solution Approach 2:
The patent creates composite materials by doping multiple metals (Mn, Co, Ni, and at least one of Al, Ti, Mg, Zr, W, Y, Sr, Co, F, Si, Na, Cu, Fe, Ca, S, or B) into the NCM crystal lattice. This composite approach enhances structural stability at high state of charge, preventing rapid deterioration while maintaining high energy density and voltage characteristics
2Reliability
If metal doping and surface coating are applied to stabilize surface structure, then lifetime characteristic at high voltage is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges metal doping and surface coating processes into a single integrated manufacturing workflow. By combining these two stabilization approaches, the patent achieves superior lifetime characteristics at high voltage while managing manufacturing complexity through process integration rather than separate sequential steps
Solution Approach 2:
The patent specifies precise parameter ranges for metal doping (2500-6000 ppm concentration) and crystal grain size (180-300 nm) to optimize the balance between reliability improvement and manufacturing feasibility. These controlled parameter changes ensure consistent performance while maintaining manageable 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 significantly improves the lifetime characteristics of lithium secondary batteries at high voltages by stabilizing the surface structure and reducing gas generation and side reactions, leading to enhanced capacity retention and operational stability.
Implementation Method 1
a metal (one or more metals selected from the group consisting of M=Al, Ti, Mg, Zr, W, Y, Sr, Co, F, Si, Na, Cu, Fe, Ca, S, and B) compound coated on the surface of the single particle, together with the metal (one or more metals selected from the group consisting of M=Al, Ti, Mg, Zr, W, Y, Sr, Co, F, Si, Na, Cu, Fe, Ca, S, and B) doped in the crystal lattice of the single particle
Implementation Method 2
calcining the first mixture at a temperature of 960° C. or higher
Implementation Method 3
calcining the first mixture at a temperature of 960° C. or higher; and calcining the second mixture at a temperature of 350° C. to 800° C.
Implementation Method 4
each of the crystal grains included in the single particle has a size of 180 nm to 300 nm, as measured by Cu Kα X ray (X-rα)
Data Source
AI summary
Exemplary embodiments of positive electrode active materials in the form of single particles, and a method of preparing each of them, are provided. The single particles of the exemplary embodiments include single particles of a nickel-based lithium composite metal oxide, having a plurality of crystal grains, each having a size of 180 nm to 300 nm, as analyzed by a Cu Kα X-ray (X-rα). The single particles include a metal doped in the crystal lattice thereof. One embodiment includes a surface coating. The total content of the metal doped in the crystal lattice thereof and the metal of the metal oxide coated on the surface thereof is controlled in the range of 2500 ppm to 6000 ppm.