Pitch-Based Anode for Sodium-Ion Batteries via Pre-Oxidation
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Solution Overview
Problem
Current negative electrode materials for sodium-ion batteries face challenges such as safety hazards due to metal sodium and thermodynamic instability of graphite, leading to low sodium storage capacity and high production costs, making it difficult to achieve high-performance and large-scale application.
Innovation Solution
A pitch-based negative electrode material is developed through pre-oxidation at low temperatures followed by high-temperature carbonization, breaking the ordered structure and forming a disordered carbon material with wedge-shaped voids, enhancing sodium storage capacity and carbon yield, and simplifying the production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pitch is directly carbonized at high temperature, then carbon material is formed, but the ordered structure is created which is not conducive to sodium-ion storage, resulting in low sodium storage capacity
Solution Approach 1:
The pitch undergoes pre-oxidation treatment before carbonization to introduce oxygen-containing functional groups and create defects in the molecular structure. This preliminary action prevents the formation of highly ordered graphite structures during subsequent high-temperature carbonization, resulting in disordered carbon with enhanced sodium-ion storage capacity while maintaining structural stability
Solution Approach 2:
The oxidation state and molecular weight distribution of pitch are modified through controlled oxidation processes. By adjusting oxidation parameters (temperature, time, oxidizing agent concentration), the pitch structure is transformed to contain more aliphatic chains and fewer aromatic layers, which upon carbonization produces disordered carbon structures favorable for sodium-ion intercalation rather than ordered graphite
2Reliability
If conventional precursors (polymers, biomass, resins) are used to prepare disordered carbon materials, then sodium storage capacity is improved, but production cost increases and preparation process becomes complex
Solution Approach 1:
Pitch, a low-cost petroleum byproduct, is used as the precursor instead of expensive polymers, biomass, or resins. The pitch is readily available, inexpensive, and can be processed through simple oxidation and carbonization steps to produce high-performance disordered carbon anodes, eliminating the need for complex synthesis procedures and expensive raw materials
Solution Approach 2:
The molecular weight and functional group composition of pitch are optimized through controlled oxidation to achieve the desired disordered carbon structure. By adjusting oxidation parameters, the pitch is transformed into a precursor with enhanced ability to form defect-rich carbon structures upon carbonization, matching the performance of complex precursors while maintaining simplicity
3Quantity of substance
If pitch is used as precursor, then cost is reduced and carbon content is increased, but the pitch is easy to be graphitized during high-temperature carbonization, resulting in low sodium storage capacity
Solution Approach 1:
Pre-oxidation is performed on pitch before carbonization to introduce oxygen-containing functional groups and create structural defects. This preliminary modification ensures that during high-temperature carbonization, the pitch forms disordered carbon with high carbon yield while preventing excessive graphitization, thereby achieving both high carbon content and high sodium storage capacity
Solution Approach 2:
The oxidation state and molecular weight distribution of pitch are modified through controlled oxidation processes. By adjusting oxidation parameters (temperature, time, oxidizing agent concentration), the pitch structure is transformed to contain more aliphatic chains and fewer aromatic layers, which upon carbonization produces disordered carbon structures favorable for sodium-ion intercalation rather than ordered graphite
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 resulting disordered carbon material exhibits high reversible capacity, energy density, excellent rate performance, and stable cycle performance, suitable for large-scale energy storage applications, including mobile equipment, electric vehicles, and renewable energy systems.
Implementation Method 1
putting the pre-oxidized pitch into a high-temperature carbonization furnace, wherein the temperature is raised to 1300° C.-1600° C. at a heating rate of 0.5° C./min-5° C./min, and performing heat treatment on the pre-oxidized pitch in an inert atmosphere for 1-10 hours, so that the pre-oxidized pitch undergoes carbonization and cracking reactions
Implementation Method 2
the pre-oxidized pitch undergoes carbonization and cracking reactions; wherein oxygen in the pre-oxidized pitch is used for breaking an ordered structure of the pitch and forming a disordered structure with wedge-shaped voids
Implementation Method 3
wherein oxygen in the pre-oxidized pitch is used for breaking an ordered structure of the pitch and forming a disordered structure with wedge-shaped voids in a process of the carbonization of the pre-oxidized pitch
Data Source
AI summary
Embodiments of the present disclosure are a pitch-based negative electrode material for a sodium-ion battery and related methods and applications. The method comprises: placing a pitch recursor into a muffle furnace to allow the pitch precursor to experience pre-oxidation for 2 to 6 hours at a temperature ranging from 200° C. to 350° C., to obtain pre-oxidized pitch; placing the pre-oxidized pitch into a high-temperature carbonization furnace, and increasing the temperature to 1300° C. to 1600° C. at a temperature increase speed of 0.5° C./min to 5° C./min, and carrying out thermal treatment on the pre-oxidized pitch in an inert atmosphere for 1 to 10 hours, to allow the pre-oxidized pitch to experience carbonization reactions, oxygen in the pre-oxidized pitch being used for breaking an ordered structure of the pitch during the carbonization of the pre-oxidized pitch, so as to form a wedge-shaped voids disordered structure.