Layered Oxide Cathode Coating for Air-Stable Sodium-Ion Batteries
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Solution Overview
Problem
Sodium ion batteries face issues of poor electrochemical performance due to poor air stability and residual alkali on the surface of O3-phase layered oxide cathode materials, which affect initial coulombic efficiency and reversible capacity.
Innovation Solution
A layered oxide cathode material with a double-layer coating structure, comprising an O3@P2-phase composite oxide particle with an O3-phase nickel-manganese-based oxide layered particle and a P2-phase metal oxide coating layer, and an inert coating layer such as a carbon or inorganic metal oxide layer, is developed to reduce residual alkali content and enhance air stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If O3-phase cathode material with high sodium content is used, then charging and discharging capacities are improved, but residual alkali content increases and air stability deteriorates
Solution Approach 1:
The patent applies composite materials by creating a core-shell structure where the core is O3-phase nickel-manganese-based oxide layered particles providing high sodium content and capacity, while the shell is P2-phase metal oxide coating layer that provides air stability. This composite structure allows the material to simultaneously achieve high charging/discharging capacities from the O3-phase core and improved air stability from the P2-phase shell, directly resolving the technical contradiction between capacity and reliability.
2Power
If O3-phase cathode material with high sodium content is used, then charging and discharging capacities are improved, but initial coulombic efficiency deteriorates
Solution Approach 1:
The composite core-shell structure with P2-phase coating layer on O3-phase core reduces residual alkali content at the surface, which directly improves initial coulombic efficiency while maintaining the high capacity benefits of the O3-phase material.
3Power
If O3-phase cathode material with high sodium content is used, then charging and discharging capacities are improved, but reversible capacity deteriorates
Solution Approach 1:
The P2-phase metal oxide coating layer on the O3-phase core reduces side reactions with electrolyte and improves structural stability, which enhances reversible capacity while preserving the high capacity characteristics of the O3-phase material.
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 layered oxide cathode material improves electrochemical performance by reducing residual alkali, enhancing air stability, and prolonging the service life of sodium ion batteries through effective sodium ion transport and reduced side reactions.
Implementation Method 1
the P2-phase metal oxide coating layer reduces the residual alkali content on the surface of the O3-phase nickel-manganese-based oxide layered particle
Implementation Method 2
the inert coating layer delays side reactions between the outer surface of the layered oxide cathode material and the air and electrolyte
Implementation Method 3
provides a good transport channel for sodium ions
Data Source
AI summary
The present disclosure provides a layered oxide cathode material and a preparation method thereof, a cathode sheet, and a sodium ion battery, and belongs to the technical field of sodium ion batteries. The layered oxide cathode material includes an O3@P2-phase composite oxide particle and an inert coating layer coated on its surface, and the O3@P2-phase composite oxide particle includes an O3-phase nickel-manganese-based oxide layered particle and a P2-phase metal oxide coating layer coated on the surface of the O3-phase nickel-manganese-based oxide layered particle; and the inert coating layer is a carbon layer and/or an inorganic metal oxide layer. When the layered oxide cathode material provided by the present disclosure is applied to the sodium ion battery, the prepared sodium ion battery has high initial coulombic efficiency, excellent rate performance, long cycle life, and good air stability.