Nickel-Rich Cathode Surface Treatment for Residual Alkali Control
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries with lithium nickel-based composite oxides face challenges in synthesizing these materials, leading to residual alkaline components that cause slurry thickening and gas generation, and methods to reduce these components often worsen cycle characteristics.
Innovation Solution
A method involving contacting lithium transition metal composite oxide particles with a sodium ion solution, followed by mixing with a boron compound and heat-treating the mixture to produce a positive electrode active material with improved cycle characteristics, where the boron is uniformly dispersed across the particle boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If water-washing is performed to reduce residual alkaline components, then slurry thickening and gas generation are reduced, but cycle characteristics worsen
Solution Approach 1:
The patent extracts residual alkaline components from the lithium nickel-based composite oxide through water-washing, removing the harmful substance while preserving the core material structure. This extraction process eliminates slurry thickening and gas generation issues without compromising cycle characteristics when combined with subsequent sulfate treatment.
Solution Approach 2:
The patent introduces sulfate as an intermediary substance that coats the surface of the lithium nickel-based composite oxide particles after water-washing. This sulfate layer acts as a protective mediator that prevents direct contact between the washed material and the electrolyte, thereby maintaining cycle characteristics while allowing the removal of residual alkaline components.
2Quantity of substance
If lithium nickel-based composite oxide is synthesized to replace cobalt, then electrical charge-discharge capacity per unit weight increases, but residual alkaline component remains
Solution Approach 1:
The patent applies preliminary water-washing treatment to the lithium nickel-based composite oxide immediately after synthesis to remove residual alkaline components before electrode fabrication. This preliminary action prevents slurry thickening issues from occurring during subsequent processing while maintaining the high capacity characteristics of the nickel-based material.
Solution Approach 2:
The patent uses sulfate as an intermediary coating substance applied to the surface of the lithium nickel-based composite oxide after washing. This sulfate layer serves as a protective barrier that allows the material to maintain its high electrical charge-discharge capacity while preventing harmful interactions that would otherwise result from residual alkaline components.
3Reliability
If sulfate is added to the surface of lithium nickel-based composite oxide, then cycle characteristics improve, but manufacturing complexity increases
Solution Approach 1:
The patent combines the sulfate treatment step with the existing water-washing process in a sequential manner. Instead of treating these as separate complex operations, the methodology integrates them into a unified surface treatment workflow where washing is followed immediately by sulfate solution immersion, simplifying the overall manufacturing process while maintaining improved cycle characteristics.
Solution Approach 2:
The patent optimizes the sulfate treatment by controlling specific parameters such as sulfate concentration, treatment time, and temperature within defined ranges. By establishing optimal parameter windows, the process achieves improved cycle characteristics through a standardized, controllable procedure that reduces manufacturing complexity despite the additional treatment step.
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 a positive electrode active material with enhanced electrical charge and discharge characteristics and cycle stability, effectively addressing the issues of residual alkaline components and improving battery performance.
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
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.
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.