Single-Particle NCM Cathode Surface Structure for High-Voltage Life
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium nickel cobalt manganese oxide (NCM) positive electrode active materials exhibit inferior performance and rapid deterioration of lifetime characteristics when used at high voltages above 4.2 V due to higher lithium deintercalation and increased instability at high state of charge (SOC).
Innovation Solution
A nickel-based lithium composite metal oxide single particle with specific crystal grain sizes and doped or coated with certain elements, such as Al, Ti, Mg, Zr, and others, to improve stability and performance at high voltages. The single particles have a size of 180 nm to 300 nm and a total metal content of 2500 to 6000 ppm, with optional surface coating to enhance characteristics.
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
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size of NCM material to 180-300 nm and doping with metal elements (Al, Ti, Mg, Zr, W, Y, Sr, Co, F, Si, Na, Cu, Fe, Ca, S, or B) at specific concentrations (2500-6000 ppm). These parameter modifications enable the material to maintain structural stability at high voltage while improving lifetime characteristics, resolving the contradiction between power and reliability
Solution Approach 2:
The patent creates composite materials by combining NCM with other metal oxides or hydroxides in specific ratios. This composite approach allows the material to benefit from the high energy density of NCM while the additional components provide structural stability and reduce degradation at high voltage, thus improving both power and reliability simultaneously
2Ease of manufacture
If NCM is used to substitute LCO for cost reduction, then manufacturing cost is improved, but performance deteriorates at high voltage
Solution Approach 1:
The patent modifies the particle size parameter to 180-300 nm and controls metal element doping at 2500-6000 ppm, which improves the electrochemical performance and stability of NCM at high voltage, making it comparable to or better than LCO while maintaining cost advantages
Solution Approach 2:
By creating composite materials with NCM and other metal compounds, the patent enhances the performance and stability of the electrode material, allowing cost-effective substitution of LCO with improved high-voltage performance
Data Source
AI summary
A positive electrode active material in the form of a single particle and a lithium secondary battery containing the positive electrode active material thereof are provided. The positive electrode active material has a nickel-based lithium composite metal oxide single particle. The single particle includes a metal doped in the crystal lattice thereof. The single particle includes, in the crystal lattice, a surface part having a rock salt structure, a spinel structure, or a mixed structure thereof from a surface of the single particle to a depth of 0.13% to 5.26% of a radius of the single particle, and a central part having a layered structure from an interface with the surface part thereof to the center part of the single particle.