Chalcogen-Coated Sodium-Ion Cathodes for Residual Alkali Control
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Solution Overview
Problem
Secondary batteries, particularly sodium-ion batteries, face challenges in cycle performance and high-temperature storage performance due to residual alkali content leading to corrosion, electrolyte residue formation, and adverse electrochemical reactions.
Innovation Solution
Incorporating a chalcogen-containing material, such as sulfur, selenium, or tellurium, in the positive electrode film layer to reduce residual alkali content, form a protective coating, and generate a solid electrolyte interphase film (SEI) that enhances interface stability and reduces side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If residual alkali remains in the positive electrode film layer, then the positive electrode plate conductivity is maintained, but corrosion occurs and electrolyte residues form leading to degraded performance
Solution Approach 1:
The patent converts the harmful residual alkali (Na2O, Na2CO3) into a beneficial protective coating by introducing chalcogen-containing materials. The residual alkali reacts with chalcogen (S, Se, or Te) to form chalcogenides (Na2S, Na2Se, Na2Te) that create a stable surface layer on the positive electrode active material, preventing further corrosion and improving cycle performance.
Solution Approach 2:
The chalcogen-containing material acts as an intermediary between the residual alkali and the positive electrode active material. It mediates the reaction to form a stable intermediate product (chalcogenide coating) that protects the electrode from direct contact between residual alkali and electrolyte, preventing harmful electrochemical reactions.
2Reliability
If residual alkali content is high, then the positive electrode film layer forms during preparation, but electrolyte residues form causing adverse electrochemical reactions
Solution Approach 1:
The patent converts the harmful electrolyte residue formation into a beneficial protective mechanism. The chalcogen-containing material reacts with residual alkali to form a stable chalcogenide coating that prevents electrolyte decomposition and residue formation, thereby improving high-temperature storage performance and preventing adverse electrochemical reactions.
3Reliability
If chalcogen-containing material is added to reduce residual alkali, then corrosion is prevented and cycle performance improves, but device complexity increases
Solution Approach 1:
The patent changes the chemical composition parameter of the positive electrode film layer by adding chalcogen-containing materials (0.1-5 wt% S, Se, or Te). This parameter change triggers a chemical reaction with residual alkali to form protective chalcogenide coatings, improving cycle performance without significantly complicating the manufacturing process.
4Stability of the object's composition
If residual alkali is present in the positive electrode plate, then the electrode structure is formed, but gas formation occurs during formation process causing structural impacts
Solution Approach 1:
The patent converts the harmful gas formation from residual alkali decomposition into a beneficial process. The chalcogen-containing material reacts with residual alkali to form stable chalcogenide coatings, preventing the decomposition that would otherwise produce CO2 and H2O gases during battery formation, thereby maintaining electrode 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
Improves cycle performance and high-temperature storage performance by preventing corrosion, reducing electrolyte residue formation, and facilitating fast charging and discharging capabilities.
Implementation Method 1
the positive electrode film layer of the chalcogen-containing material can form a coating layer in situ on the surface of the positive electrode active material
Implementation Method 2
the reducing chalcogen-containing material can undergo reduction and oxidation reactions in the electrolytic solution. This leads to the formation of a solid electrolyte interphase film (SEI film) at the interface where the negative electrode plate and the electrolyte are in contact
Data Source
AI summary
A secondary battery and a preparation method therefor, and an electric apparatus. The secondary battery comprises a positive electrode plate, which positive electrode plate comprises a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode active material and a material containing a chalcogen element. The secondary battery and an electric apparatus including the secondary battery have improved cycle performance and high-temperature storage performance.