Low-Cobalt Single-Crystal Cathode With Co-Rich Surface for Li-Ion Batteries
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Solution Overview
Problem
Lithium-ion batteries face challenges with reduced cycle performance, power, and increased cost due to high cobalt content, especially at low temperatures and high voltages, necessitating a positive active material with improved electrochemical performance and lower manufacturing costs.
Innovation Solution
A single-crystalline low-cobalt ternary positive material with a chemical formula Li1+x (NiaCobMnc)1−dMdO2−yAy, where M is Zr, Sr, B, Ti, Mg, or Al, and A is S, N, F, Cl, Br, or I, with a Co content ratio of 1.2-5.0:1 between the outer and inner layers, and a particle radius of 300-4000 nm, optionally coated with oxides, is developed to enhance structural stability and power performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high cobalt content ternary materials are used, then power and cycle performance are improved, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the outer layer has high cobalt content (1.2-5.0:1 ratio compared to inner core) to improve surface electrochemical activity and cycle performance, while the inner core has lower cobalt content to reduce overall material cost. This non-uniform distribution optimizes both performance and cost by placing cobalt only where it provides maximum benefit.
Solution Approach 2:
The patent uses composite materials by combining multiple elements (Ni, Co, Mn, Al, Ti, B, Sr, Mg) in a ternary system with a core-shell structure. The composite nature allows the outer shell to provide high power and cycle performance while the inner core reduces cost, achieving a balance between performance requirements and manufacturing cost.
2Power
If high cobalt content ternary materials are used, then power performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by concentrating high cobalt content in the outer layer (1.2-5.0:1 ratio compared to inner core) where it directly contacts the electrolyte and provides electrochemical activity. This localized high cobalt region delivers superior power performance while the lower cobalt inner core reduces overall material cost.
Solution Approach 2:
The patent uses parameter changes by precisely controlling the cobalt content gradient from outer layer to inner core, with the cobalt ratio optimized in the range of 1.2-5.0:1. This parameter optimization ensures sufficient power performance from the cobalt-rich surface while minimizing total cobalt usage and manufacturing cost.
3Power
If conventional ternary materials are used, then electrochemical performance at high voltage is improved, but structural stability deteriorates
Solution Approach 1:
The patent uses composite materials by incorporating multiple stabilizing elements (Al, Ti, B, Sr, Mg) alongside Ni, Co, and Mn in a ternary system. These additional elements strengthen the crystal structure and improve structural stability at high voltage, while the core-shell cobalt distribution maintains high electrochemical performance.
Solution Approach 2:
The patent applies local quality by creating distinct functional zones: the outer layer with high cobalt content provides electrochemical activity and power performance, while the inner core with lower cobalt and additional stabilizing elements maintains structural stability. This spatial differentiation resolves the contradiction between performance and stability.
Data Source
AI summary
A single-crystalline-structured low-cobalt ternary positive material, a chemical formula thereof is Li1+x(NiaCObMnc)1−dMdO2−yAy, where a mole fraction of Co element is low, 0.05≤b≤0.14; and in a single particle, a ratio of an average Co content per unit area of an outer layer to an average Co content per unit area of an inner core in a cross section passing through a geometric center of the particle is in a range 1.2-5.0:1, optionally, in a range 1.4-2.0:1 is disclosed. The material has better structural stability and dynamic performance at low temperature and high voltage, which improves cycle performance and power performance of the secondary battery at low temperature and high voltage. A method for preparing the low-cobalt ternary positive material, a secondary battery, a battery module, a battery pack, and a power consumption apparatus including the material is also disclosed.