Doped NCM Single-Particle Cathode 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 crystal grain sizes and surface or lattice doping/coating of metals like Al, Ti, Mg, Zr, and Co, calcined at controlled temperatures to enhance stability and reactivity, resulting in a positive electrode active material with improved high-voltage performance.
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 particle size of NCM material to D50=5 μm or less and controlling crystal grain size to 180-300 nm, which fundamentally alters the electrochemical behavior of the material. These parameter changes enable the material to maintain structural stability at high voltages while improving lithium deintercalation characteristics, thus resolving the contradiction between high voltage performance and lifetime durability
Solution Approach 2:
The patent uses composite materials by combining NCM positive electrode active material with specific binders and conductive agents in optimized ratios. This composite structure enhances the overall stability of the electrode at high voltages while maintaining high energy density, effectively preventing the rapid deterioration of lifetime characteristics that occurs with pure NCM material
2Ease of manufacture
If NCM positive electrode active material is used to substitute LCO for cost competitiveness, then manufacturing cost is reduced, but performance becomes inferior at high voltage due to rapid deterioration
Solution Approach 1:
The patent achieves both cost-effectiveness and performance stability by controlling critical parameters: particle size D50=5 μm or less and crystal grain size 180-300 nm. These parameter controls enable NCM to match or exceed LCO performance at high voltages while maintaining the cost advantage, eliminating the need to sacrifice performance for cost reduction
3Quantity of substance
If lithium deintercalation is increased to improve capacity, then energy density is improved, but structural instability increases at high state of charge leading to rapid deterioration
Solution Approach 1:
The patent resolves this contradiction through parameter changes in particle size (D50≤5 μm) and crystal grain size (180-300 nm), which fundamentally alter the stress distribution and ion transport pathways. These changes enable high lithium deintercalation (improved capacity) while maintaining structural integrity at high state of charge, preventing the rapid deterioration that would otherwise occur
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 internal metal release, leading to enhanced capacity retention and efficiency.
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) doped in a crystal lattice of the single particle
Implementation Method 2
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
Implementation Method 3
calcining the first mixture at a temperature of 960° C. or higher
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 has a plurality of crystal grains. An average particle size (D50) of the single particle is from 3.5 μm to 8 μm. The single particle includes a metal doped in the crystal lattice thereof.