NMC Cathode Material Surface Boron Coating to Prevent Paste Gelation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing positive electrode active materials for nonaqueous electrolyte secondary batteries face challenges in maintaining high output characteristics and battery capacity while preventing gelation of the electrode mixture paste during production, particularly when boron is added.
Innovation Solution
A specific amount of a boron compound is applied to the surfaces of lithium-nickel-cobalt-manganese composite oxide particles, with a controlled water-soluble lithium amount, to enhance output characteristics and inhibit gelation, using a method that includes crystallization, lithium mixing, firing, boron mixing, and heat treatment processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If boron compound is added to lithium-nickel-cobalt-manganese composite oxide to improve output characteristics, then conductivity is improved, but gelation of positive electrode mixture paste occurs during production
Solution Approach 1:
The patent applies local quality by concentrating boron compound specifically on the surface of primary particles rather than uniformly distributing it throughout the entire material. This localized surface coating improves conductivity where needed (at particle surfaces) while minimizing the total amount of boron compound required, thereby preventing gelation during electrode production.
Solution Approach 2:
The patent segments the material structure into primary particles and secondary particles, with boron compound applied only to the primary particle surfaces. This segmentation allows precise control of boron distribution, ensuring conductivity enhancement at critical interfaces while avoiding excessive boron content that would cause gelation in the mixture paste.
2Quantity of substance
If lithium-nickel-cobalt-manganese composite oxide is used to achieve high capacity, then battery capacity is improved, but resistance increases making high output difficult to obtain
Solution Approach 1:
The patent creates a composite material system by combining lithium-nickel-cobalt-manganese composite oxide with boron compound on its surface. This composite structure leverages the high capacity of the lithium-nickel-cobalt-manganese oxide core while the boron-containing surface layer provides enhanced conductivity, thereby achieving both high capacity and high output characteristics simultaneously.
3Ease of manufacture
If cobalt content is decreased to reduce cost, then manufacturing cost is reduced, but output characteristics degrade
Solution Approach 1:
The patent changes the chemical composition parameters by introducing boron compound on the particle surface. This parameter change compensates for the reduced cobalt content in the bulk material, as the boron-containing surface layer provides additional conductivity enhancement, thereby maintaining output characteristics even with lower cobalt content and reduced manufacturing cost.
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 approach results in improved output characteristics and battery capacity while preventing gelation of the positive electrode mixture paste, facilitating easier industrial-scale production of high-performance nonaqueous electrolyte secondary batteries.
Implementation Method 1
a boron compound containing lithium is made present on surfaces of the primary particles
Implementation Method 2
the boron mixture is heat-treated in an oxidative atmosphere at a temperature of at least 200°C and up to 300°C
Implementation Method 3
having a hexagonal layered crystal structure
Implementation Method 4
the lithium-nickel-cobalt-manganese composite oxide contains a secondary particle formed of a plurality of flocculated primary particles
Data Source
Figure 1(A)~1(B)
Figure 2
Figure 3
AI summary
Provided is a positive electrode active material that has high output characteristics and battery capacity - when used for a positive electrode of a nonaqueous electrolyte secondary battery and can inhibit gelation of positive electrode mixture paste. A method for producing the positive electrode active material is also provided. A positive electrode active material for a nonaqueous electrolyte secondary battery contains a lithium-nickel-cobalt-manganese composite oxide represented by General Formula (1) : Li1+sNixCoyMnzBtM1uO2+β and having a hexagonal layered crystal structure. The lithium-nickel-cobalt-manganese composite oxide contains a secondary particle formed of a plurality of flocculated primary particles and a boron compound containing lithium present at least on part of surfaces of the primary particles. A water-soluble Li amount present on the surfaces of the primary particles is up to 0.1% by mass relative to the entire amount of the positive electrode active material.