Core-Shell Cathode Material for Sodium-Ion Battery Cycling Stability
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Solution Overview
Problem
The poor conductivity of pyrophosphate-based positive electrode materials in sodium-ion batteries hinders their large-scale application due to reduced gram capacity and electrochemical performance, leading to poor cycling performance.
Innovation Solution
A positive electrode active material with a core-shell structure is developed, comprising a phosphate-based sodium salt core and a metal oxide shell on a conductive carbon base, enhancing conductivity and preventing direct contact with electrolytes to reduce side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If pyrophosphate-based positive electrode material is used directly, then cost is reduced and resource availability is improved, but conductivity is poor leading to reduced gram capacity and electrochemical performance
Solution Approach 1:
The patent applies composite materials by combining pyrophosphate-based active substance with conductive carbon materials and metal oxides to form a composite positive electrode material. This composite structure integrates the low cost and abundant resource availability of pyrophosphate materials with the high conductivity of carbon and metal oxide components, resolving the contradiction between cost-effectiveness and electrical conductivity.
Solution Approach 2:
The patent introduces conductive carbon materials and metal oxides as intermediary substances that mediate between the pyrophosphate active substance and the electrolyte. These intermediaries improve electron and ion transport pathways, enhancing conductivity without compromising the cost advantages of pyrophosphate-based materials.
2Device complexity
If pyrophosphate-based positive electrode material is used directly, then material simplicity is maintained, but gram capacity performance and kinetic performance are reduced
Solution Approach 1:
The patent constructs a composite material system where pyrophosphate-based active substance is combined with conductive carbon materials and metal oxides. This composite approach enhances gram capacity and kinetic performance by improving electron and ion transport, while maintaining relatively simple preparation processes suitable for large-scale production.
Solution Approach 2:
The patent applies local quality by creating regions with different properties within the positive electrode material. The conductive carbon materials and metal oxides are distributed throughout the pyrophosphate matrix to locally enhance conductivity and reaction kinetics, while the bulk pyrophosphate maintains its cost-effective composition.
3Ease of manufacture
If pyrophosphate-based positive electrode material is used directly, then preparation process simplicity is maintained, but cycling performance is poor
Solution Approach 1:
The patent employs composite materials comprising pyrophosphate-based active substance, conductive carbon materials, and metal oxides. This composite structure improves cycling performance by enhancing structural stability and conductivity during charge-discharge cycles, while the preparation process remains relatively simple and suitable for existing manufacturing facilities.
Solution Approach 2:
The patent applies beforehand cushioning by incorporating conductive carbon materials and metal oxides into the positive electrode structure before battery operation. These components pre-establish conductive pathways and structural support that cushion against degradation during cycling, improving long-term reliability without complicating the preparation process.
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 core-shell structure improves the gram capacity and kinetic performance of the electrode material, while maintaining stability during charging and discharging, and reduces side reactions, thereby enhancing cycling performance.
Implementation Method 1
the shell layer material comprises a metal oxide... the conductivity of the positive electrode active material can be effectively improved
Implementation Method 2
the active substance having a core-shell structure... prevents direct contact with electrolytes to reduce side reactions
Data Source
AI summary
A positive electrode active material includes a conductive base material and an active substance distributed at the conductive base material. The active substance has a core-shell structure including a core layer material and a shell layer material. The conductive base material includes a carbon material, the core layer material includes a phosphate-based sodium salt material, and the shell layer material includes a metal oxide.