Sodium-Rich Cathode Material for Stable Sodium-Ion Battery Cycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The surface of positive electrode active materials in sodium-ion batteries often contains high amounts of free alkaline substances, which adversely affect battery performance, and existing sodium supplementation methods result in uneven mixing and poor electrochemical consistency.
Innovation Solution
A positive electrode active material with a sodium-rich layer formed in situ on a sodium-containing layered transition metal oxide matrix, using sodium salts represented by Formulas (I) and (II), which are uniformly dispersed to minimize direct contact with the electrolyte and provide additional sodium during charging, compensating for sodium loss during cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If free alkaline substances are present on the surface of positive electrode active material, then the material can be easily prepared, but battery performance deteriorates due to side reactions
Solution Approach 1:
The patent converts the harmful free alkaline substances on the surface into beneficial sodium carbonate through controlled carbonation treatment. The alkaline substances that cause side reactions are transformed into a stable protective layer that prevents further degradation while maintaining electrochemical performance.
Solution Approach 2:
The patent removes harmful free alkaline substances from the surface through carbonation treatment, extracting the problematic component while retaining the beneficial sodium-containing layered transition metal oxide structure. This selective removal improves battery performance without compromising the active material.
2Reliability
If sodium supplement is added to compensate for sodium loss, then cycling performance improves, but mixing uniformity deteriorates leading to poor electrochemical consistency
Solution Approach 1:
The patent combines the sodium supplement with the positive electrode active material through co-precipitation or solid-state reaction, creating a composite structure where sodium is uniformly distributed within the material matrix. This merging ensures consistent sodium content throughout the electrode, improving electrochemical consistency while maintaining cycling performance.
Solution Approach 2:
The patent performs preliminary sodium supplementation during the material synthesis stage rather than adding it later during electrode fabrication. By incorporating sodium into the active material structure beforehand, uniform distribution is achieved, avoiding the mixing uniformity problems that arise from post-synthesis addition.
3Reliability
If sodium salts are uniformly dispersed on matrix surface, then direct contact with electrolyte is minimized, but preparation complexity increases
Solution Approach 1:
The patent employs self-assembly mechanisms where sodium salts automatically organize themselves on the matrix surface through electrostatic attraction or surface energy minimization. This self-service approach creates uniform dispersion without requiring complex external processing steps, maintaining cycle stability while avoiding excessive preparation complexity.
Solution Approach 2:
The patent utilizes the porous or layered structure of the sodium-containing layered transition metal oxide to naturally accommodate and disperse sodium salts on its surface. The inherent surface area and porosity provide numerous anchoring sites, enabling uniform distribution through simple impregnation or surface treatment methods.
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
Enhances energy density and cycling performance by reducing side reactions, improving structural stability, and ensuring consistent sodium supplementation, leading to higher specific capacity and longer cycle life.
Implementation Method 1
The desodiation process of the sodium salts represented by Formula (I) and Formula (II) during the initial charging process of the battery is irreversible.
Implementation Method 2
During desodiation, the sodium salts also decompose to produce carbon dioxide, which is subsequently released as a gas, while the solid residue after desodiation primarily remains on the matrix surface in the form of elemental carbon
Data Source
AI summary
The present application provides a positive electrode active material, a preparation method thereof, and a positive electrode plate, a battery cell, a battery, and an electric device containing the same, where the positive electrode active material includes a matrix and a sodium-rich layer formed in situ on the surface of the matrix, the matrix includes a sodium-containing layered transition metal oxide, and the sodium-rich layer includes one or more of sodium salts represented by Formula (I) and Formula (II), where m represents an integer from 1 to 8, and n represents an integer from 2 to 20.