Sodium-Ion Cathode Composition with Fe2+ Redox for Higher Energy Density
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Solution Overview
Problem
The existing sodium-ion battery cathode materials, particularly Na x MO 2 , face challenges in maintaining cost-effectiveness and improving energy density as lithium prices fluctuate, necessitating enhancements to enhance capacity and reduce material watt-hour costs.
Innovation Solution
A cathode active material with a controlled change in Fe 2+ content (Δn≥0.1) during charging, formulated as Na a1 Ni x1 Fe y1 Mn z1 Zn m1 Ca n1 M p1 O 2 , where M includes specific elements, is prepared through a calcination process with precise temperature control, enhancing electron transfer and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Na x MO 2 materials are used as cathode active material, then manufacturing cost is reduced due to abundant and low-priced sodium resources, but energy density is insufficient and material watt-hour cost needs to be reduced further
Solution Approach 1:
The patent modifies the cathode material composition by controlling the Fe2+ content change (Δn≥0.1) during charging to 4.0V, adjusting the chemical parameters of the material to achieve higher capacity while maintaining cost-effectiveness through sodium-based chemistry
Solution Approach 2:
The patent uses a composite cathode material with formula Na a1 Ni x1 Fe y1 Mn z1 Zn m1 Ca n1 M p1 O 2, combining multiple elements (Ni, Fe, Mn, Zn, Ca, and other dopants) to achieve synergistic effects that improve energy density while maintaining manufacturing cost advantages
2Quantity of substance
If the content of Fe 2+ changes by Δn≥0.1 during charging to 4.0 V, then electron transfer capacity and energy density are improved, but structural stability may be compromised
Solution Approach 1:
The patent introduces localized doping with Ca and other elements (M) at specific positions in the crystal structure to stabilize local regions while allowing Fe2+ content to change dynamically in other regions, achieving both high electron transfer capacity and structural stability
Solution Approach 2:
The patent pre-dopes the cathode material with Ca and other stabilizing elements before charging to create a structurally robust framework that can accommodate subsequent Fe2+ content changes (Δn≥0.1) without compromising overall structural stability
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 modified cathode active material increases electron transfer capacity, improving energy density and air stability, while maintaining structural integrity and cycle performance.
Implementation Method 1
enhancing electron transfer and energy density
Implementation Method 2
a change Δn in a content of Fe 2+ during a process of charging to 4.0 V
Implementation Method 3
calcining the mixed material in an oxidizing atmosphere
Implementation Method 4
calcining the mixed material in an oxidizing atmosphere
Data Source
Figure 1~2
Figure 3~4
Figure 5(a)~5(d)
AI summary
Provided are a cathode active material and a preparation method thereof, a positive electrode plate, a battery, and an electrical device. The present disclosure relates to the technical field of batteries. A change Δn in a content of Fe2+ in the cathode active material satisfies Δn≥0.1 and Δn=n1-n2; n1 is a content of Fe2+ in the cathode active material prior to charging, and n2 is a content of Fe2+ in the cathode active material when charging to 4.0 V; and the content of Fe2+ = amount of Fe2+substance in the cathode active material/(the amount of Fe2+substance in the cathode active material + amount of Fe3+substance in the cathode active material). Therefore, by using the cathode active material, a battery loaded with the cathode active material can have excellent energy density.