Sodium-Ion Cathode Precursor Composition for Capacity and Cycle Life
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Solution Overview
Problem
The commercialization of sodium-ion batteries is hindered by low energy density, capacity, and poor cycle life of layered transition metal oxides used as positive electrode materials, despite their potential for high stability and capacity.
Innovation Solution
A sodium-ion battery positive electrode material precursor with a chemical formula NixMnyFe1-x-y(OH)2, containing ≤4000 ppm S and a Na/S mass ratio ≤1.5, is synthesized through a co-precipitation method, optimizing particle size, specific surface area, tap density, and spherical shape, using controlled addition rates of reactants and calcination at 780-880°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If layered transition metal oxides are used as positive electrode materials, then high capacity and good stability are achieved, but low energy density and poor cycle life result
Solution Approach 1:
The patent applies parameter changes by precisely controlling the sulfur content (≤4000 ppm) and Na/S mass ratio (≤1.5) in the precursor material, as well as optimizing the particle size distribution (D50: 3-14 μm) and specific surface area (6-11 m2/g). These parameter optimizations resolve the contradiction by achieving both high energy density (>165 mAh/g at 0.1C) and improved cycle life (>78% capacity retention after 50 cycles).
Solution Approach 2:
The patent uses composite materials by creating a multi-element precursor NixMnymFe1-x-y(OH)2 containing nickel, manganese, and iron in specific ratios, with controlled sulfur doping. This composite structure achieves synergistic effects that simultaneously improve energy density and cycle stability, resolving the technical contradiction between these two performance parameters.
2Quantity of substance
If layered transition metal oxides are used as positive electrode materials, then high capacity is achieved, but poor cycle life results
Solution Approach 1:
The patent resolves this contradiction through parameter changes by optimizing the precursor composition with controlled sulfur content (≤4000 ppm) and Na/S mass ratio (≤1.5), along with specific particle size (D50: 3-14 μm) and surface area (6-11 m2/g). These parameters enable the material to achieve high capacity (>165 mAh/g) while maintaining excellent cycle life (>78% retention after 50 cycles).
Solution Approach 2:
The patent applies local quality by creating non-uniform sulfur distribution and controlled surface properties with specific surface area (6-11 m2/g) and particle morphology. The sulfur is strategically positioned to modify local electronic structure and surface chemistry, enhancing both capacity and cycle stability simultaneously.
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 precursor enhances battery capacity and cycle life, with 0.1C initial discharge capacity >165 mAh/g, 1C discharge capacity >154 mAh/g, and 50-cycle capacity retention rate >78%, while reducing defects and improving electrical properties.
Implementation Method 1
a preparation method for the sodium-ion battery positive electrode material precursor, including: mixing raw materials including a nickel source, a manganese source, a ferrous source and water to obtain a mixed salt solution, and mixing materials including water, a part of a complexing agent and a part of a precipitating agent to obtain a base solution; and adding the remaining complexing agent, the remaining precipitating agent and the mixed salt solution to the base solution to carry out a co-precipitation reaction
Implementation Method 2
containing ≤4000 ppm S and a Na/S mass ratio ≤1.5, is synthesized through a co-precipitation method, optimizing particle size, specific surface area, tap density, and spherical shape, using controlled addition rates of reactants and calcination at 780-880°C
Data Source
AI summary
A precursor for sodium-ion battery positive electrode material and a preparation method therefor, a sodium-ion battery positive electrode material, a sodium-ion battery, and an electrical device are provided. The precursor for sodium-ion battery positive electrode material has a chemical general formula of NixMnyFe1-x-y(OH)2, wherein 0.15≤x≤0.35, and 0.2≤y≤0.5. The precursor for sodium-ion battery positive electrode material contains a S element with a content of ≤4000 ppm, and has a Na/S mass ratio of ≤1.5.