Low-Cobalt Cathode Active Material for High-Temperature Stability
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving long lifespan, high energy density, and structural stability, particularly when the size of lithium metal oxide cathode active materials increases, leading to degraded capacity and power properties.
Innovation Solution
A cathode active material for lithium secondary batteries is developed, comprising lithium metal oxide particles with specific compositions and properties, including a balanced ratio of nickel and cobalt, and adjusted modulus, hardness, and particle size, which satisfy the equation E/H/D50 > 1.3, enhancing structural stability and high-temperature storage properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the size of lithium metal oxide particles is increased to achieve high energy density, then energy density is improved, but capacity and power properties are degraded
Solution Approach 1:
The patent applies parameter changes by precisely controlling particle size (D50 between 2.0-10.0 μm), cobalt content (15 mol% or less), and mechanical properties (modulus E between 30-100 GPa, hardness H between 5.0-20.0 GPa). These parameter optimizations enable the cathode material to achieve high energy density while maintaining good capacity and power properties through the balanced mechanical strength and ion transport capabilities
2Stability of the object's composition
If cobalt content is increased to improve structural stability, then structural stability is improved, but manufacturing cost increases
Solution Approach 1:
The patent optimizes cobalt content to 15 mol% or less of all metal elements excluding lithium, balancing structural stability with cost reduction. This parameter optimization allows the material to maintain adequate structural stability while significantly reducing cobalt consumption and manufacturing costs
Solution Approach 2:
The patent creates a composite cathode material with lithium metal oxide particles containing nickel, cobalt, and other metal elements in specific ratios. This composite approach allows the material to achieve structural stability through synergistic effects of multiple elements rather than relying heavily on expensive cobalt
3Productivity
If nickel content is increased to improve capacity, then capacity is improved, but high-temperature storage properties are degraded
Solution Approach 1:
The patent optimizes nickel content to between 50-98 mol% of all metal elements excluding lithium, balancing capacity with high-temperature stability. Simultaneously, it controls the modulus-hardness-particle size relationship (2.5 > (E/H)/D50 > 1.3) to ensure structural stability at high temperatures while maintaining high capacity
Solution Approach 2:
The patent develops a composite lithium metal oxide material combining nickel with cobalt and other metal elements in optimized ratios. This composite structure leverages nickel's high capacity characteristics while using cobalt and other elements to enhance high-temperature storage properties and structural stability
Data Source
Figure 1~2
AI summary
A cathode active material for a lithium secondary battery according to an embodiment includes lithium metal oxide particles containing lithium and nickel, and containing a small amount of cobalt or no cobalt. An average particle diameter, a modulus and a hardness of the lithium metal oxide particles are adjusted to satisfy a desired relation. A lithium secondary battery has improved high-temperature storage properties, structural stability and high power properties.