Positive Electrode Active Material for Low-Alkali Cycle Stability
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Solution Overview
Problem
The synthesis of lithium nickel-based composite oxides for non-aqueous electrolyte secondary batteries is challenging, and residual alkaline components can cause issues like slurry thickening and gas generation during electrode fabrication, which adversely affect the battery's cycle characteristics.
Innovation Solution
A method involving the use of sodium ions to treat lithium transition metal composite oxides, followed by mixing with a boron compound and heat-treating the mixture at specific temperatures to create a positive electrode active material with improved cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If water-washing is performed to reduce residual alkaline component, then slurry thickening and gas generation are reduced, but cycle characteristics deteriorate
Solution Approach 1:
Sodium ions serve as an intermediary substance during the washing process. The sodium ions replace residual alkaline components through ion exchange, allowing the removal of harmful alkaline residues without directly contacting water with the lithium nickel-based composite oxide particles, thereby preventing water-induced degradation of cycle characteristics
Solution Approach 2:
The invention changes the chemical parameter of the washing solution from water (neutral pH) to a sodium ion-containing solution (alkaline pH). This parameter change allows effective removal of residual alkaline components through ion exchange while maintaining conditions that preserve the structural integrity and electrochemical performance of the composite oxide particles
2Reliability
If sulfate is added to improve cycle characteristics, then cycle characteristics improve, but manufacturing complexity increases
Solution Approach 1:
The invention extracts and separates the sulfate treatment step from the washing process. By removing residual alkaline components first through sodium ion washing, then separately applying sulfate treatment, the process simplifies each individual step while achieving both alkaline removal and cycle characteristic improvement without the complexity of combined treatments
3Reliability
If boron compound is mixed and heat-treated to improve cycle characteristics, then cycle characteristics improve, but energy consumption increases
Solution Approach 1:
The sodium ion washing treatment is performed as a preliminary action before boron compound mixing and heat treatment. This preliminary removal of residual alkaline components creates a cleaner surface and more uniform starting material, allowing the subsequent boron treatment to be more effective at lower temperatures and shorter durations, thereby reducing overall energy consumption
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 method results in a positive electrode active material with enhanced electrical charge and discharge characteristics and improved cycle stability by uniformly dispersing boron across the particle boundaries, reducing resistance and maintaining capacity over multiple cycles.
Implementation Method 1
contacting first particles that contain a lithium transition metal composite oxide with a solution containing sodium ions to obtain second particles containing the lithium transition metal composite oxide and sodium element
Implementation Method 2
heat-treating the mixture at a temperature in a range of from 100° C. to 450° C.
Implementation Method 3
heat-treating the mixture at a temperature in a range of from 100° C. to 450° C.
Data Source
AI summary
A method of producing a positive electrode active material, the method includes: contacting first particles that contain a lithium transition metal composite oxide with a solution containing sodium ions to obtain second particles containing the lithium transition metal composite oxide and sodium element, wherein the lithium transition metal composite oxide has a layered structure and a composition ratio of a number of moles of nickel to a total number of moles of metals other than lithium in a range of from 0.7 to less than 1; mixing the second particles and a boron compound to obtain a mixture; and heat-treating the mixture at a temperature in a range of from 100° C. to 450° C.