Positive Electrode Active Material Moisture Resistance
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Solution Overview
Problem
Non-aqueous secondary batteries, particularly those with high nickel ratio lithium metal composite oxides, face issues with moisture resistance and variation in charge-discharge capacity due to water-soluble lithium compounds, leading to quality variations and increased production costs when used in large-sized applications.
Innovation Solution
The development of a positive electrode active material with core particles having a water-soluble lithium compound content of 1.0% or less, treated with a coupling agent to enhance moisture resistance, involves a washing step to remove impurities and a surface treatment step to improve stability and reduce moisture absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium-nickel composite oxide is used to increase charge-discharge capacity, then capacity per unit mass is improved, but synthesis difficulty and moisture resistance deteriorate
Solution Approach 1:
The patent modifies the chemical composition parameters of the lithium metal composite oxide by incorporating specific metal elements (M1 and M2) in controlled amounts. The formula LixNiyM1(1-y-z)M2zO2 with specific ranges for x, y, and z allows optimization of both capacity and synthesizability. This compositional parameter change enables easier synthesis while maintaining high nickel content for capacity.
Solution Approach 2:
The patent creates a composite material system by combining lithium, nickel, and other metal elements (Co, Mn, Al, Ti, Zr, etc.) in a layered oxide structure. This composite approach leverages the advantages of each element: nickel for capacity, cobalt/manganese/aluminum for structural stability, and titanium/zirconiun for enhanced properties, achieving both high capacity and ease of manufacture.
2Quantity of substance
If lithium metal composite oxide is used as positive electrode active material, then charge-discharge capacity is improved, but moisture resistance deteriorates due to water-soluble lithium compounds
Solution Approach 1:
The patent严格控制 water-soluble lithium compound content to 1.0% or less by mass ratio, changing the chemical composition parameters to achieve this threshold. This parameter control directly addresses moisture resistance while preserving the high capacity characteristics of lithium-nickel composite oxide.
Solution Approach 2:
The patent removes or minimizes the harmful water-soluble lithium compounds that cause moisture sensitivity, effectively eliminating the problematic component while retaining the beneficial high-capacity lithium metal composite oxide structure.
3Reliability
If washing treatment is applied to reduce water-soluble lithium compound content, then moisture resistance is improved, but production complexity increases
Solution Approach 1:
The patent incorporates moisture resistance improvement measures during the synthesis process itself, rather than requiring separate post-synthesis washing steps. By controlling composition parameters and removing water-soluble compounds during manufacturing, the process achieves moisture resistance without adding significant production complexity.
4Quantity of substance
If high nickel ratio is used to increase capacity, then charge-discharge capacity is improved, but quality variation increases in large-scale production
Solution Approach 1:
The patent defines specific parameter ranges for the formula LixNiyM1(1-y-z)M2zO2 where 0.6≤y≤1.0 for nickel content and 0≤z≤0.02 for M2 element content. These controlled parameter specifications ensure consistent quality across large-scale production while maintaining high nickel ratios for capacity.
Solution Approach 2:
The composite material structure with multiple metal elements provides structural stability that reduces quality variation during large-scale production. The presence of stabilizing elements (M1 and M2) compensates for the high nickel content, ensuring consistent performance across batches.
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
This approach maintains long-term moisture resistance and reduces quality variations in non-aqueous secondary batteries, even when produced in larger quantities, thereby stabilizing battery performance and reducing production costs.
Implementation Method 1
a surface-treated portion obtained by treating the core particles with a coupling agent
Data Source
AI summary
The present invention provides a positive electrode active material for a non-aqueous secondary battery including: core particles including, as a main component, a lithium metal composite oxide represented by the following formula: LixNiyM11-y-zM2zO2 in which 0.90≤x≤1.50, 0.6≤y≤1.0, 0≤z≤0.02, M1 represents at least one element selected from Co, Mn and Al, and M2 represents at least one element selected from the group consisting of Zr, Ti, Mg, B and W, and containing a water-soluble lithium compound in a content of 1.0% or less in terms of a mass ratio; and a surface-treated portion obtained by treating the core particles with a coupling agent.