X/Hard Carbon Composite Anode for Sodium-Ion Batteries
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Solution Overview
Problem
Current anode materials for sodium-ion batteries, such as graphite, suffer from limited capacity and stability due to the large atomic radius of sodium, and existing methods for improving hard carbon composite materials are costly, complex, and unsuitable for large-scale production.
Innovation Solution
A process for preparing hard carbon composite materials involving the heating of mixtures containing hard carbon and metal or metal oxide starting materials, with secondary carbon-containing materials, to create a composite with uniformly dispersed components, improving conductivity and stability, and allowing for control of particle size and composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If graphite is used as anode material for sodium-ion batteries, then high gravimetric and volumetric capacity is achieved, but electrochemical activity towards sodium is severely restricted due to large atomic radius of sodium
Solution Approach 1:
The patent employs hard carbon composite materials that combine disordered carbon structures with metallic components (such as tin, antimony, or their oxides). This composite approach allows the material to accommodate sodium ions through the disordered carbon layers while the metallic components provide additional active sites for sodium insertion, thereby maintaining high capacity while improving electrochemical activity towards sodium.
Solution Approach 2:
The patent modifies the structural parameters of carbon anodes by creating hard carbon with specific disordered layer arrangements and micropore structures. By controlling the carbonization process and incorporating metallic particles, the patent changes the interlayer spacing and structural flexibility to accommodate the larger sodium atomic radius, thus improving electrochemical activity while maintaining capacity.
2Reliability
If hard carbon materials with disordered structures are used to overcome insertion issues for sodium ions, then electrochemical activity is improved, but capacity is limited to below 300 mAh/g and insertion kinetics are slow
Solution Approach 1:
The patent creates composite materials combining hard carbon with metallic components (tin, antimony, or their oxides) that have high sodium storage capacity. The metallic particles dispersed within the hard carbon matrix provide additional active sites for sodium insertion, pushing the overall capacity above 300 mAh/g while maintaining the electrochemical activity benefits of the disordered carbon structure.
Solution Approach 2:
The patent introduces metallic particles at specific locations within the hard carbon structure to create local regions of high electrochemical activity. The disordered carbon layers provide a flexible matrix that facilitates sodium ion transport to these metallic sites, thereby improving both capacity and insertion kinetics through localized enhancement of reactive sites.
3Quantity of substance
If metals and alloys are used as high-capacity anodes, then capacity is significantly increased, but structural stability deteriorates due to severe expansion and contraction during charge/discharge
Solution Approach 1:
The patent embeds metallic particles (tin, antimony, or their oxides) within the matrix of hard carbon, creating a nested structure where the metal is contained within the carbon framework. The hard carbon shell accommodates the volume expansion and contraction of the metallic core during sodium insertion and extraction, preventing pulverization while maintaining high capacity.
Solution Approach 2:
The hard carbon matrix acts as a flexible shell surrounding the metallic particles. This carbon shell can expand and contract elastically during charge/discharge cycles, accommodating the volume changes of the metallic core without causing structural failure. The flexible nature of the disordered carbon structure prevents pulverization while maintaining structural integrity and high capacity.
4Stability of the object's composition
If nanosized metal particles are used to reduce expansion/contraction, then structural stability is improved, but manufacturing complexity increases and uniform dispersion is difficult to achieve
Solution Approach 1:
The patent combines the synthesis of hard carbon and metallic particles into a single integrated process. By co-pyrolyzing a mixture of carbon precursor and metal salt in one step, the patent simultaneously forms the hard carbon matrix and distributes metallic particles throughout it, achieving uniform dispersion without requiring separate nanofabrication steps or complex assembly procedures.
Solution Approach 2:
The patent employs a self-assembly approach where metallic particles are uniformly distributed within the hard carbon matrix during the co-pyrolysis process. The thermal treatment simultaneously carbonizes the organic precursor and reduces the metal salts, causing the metal particles to form in situ within the developing carbon structure. This self-service mechanism achieves uniform dispersion and structural stability without requiring complex external manufacturing interventions.
5Ease of manufacture
If conventional hard carbon production methods are used, then manufacturing is simplified, but capacity is limited and insertion kinetics are slow
Solution Approach 1:
The patent merges the synthesis of hard carbon with the incorporation of metallic components into a single pyrolysis step. By mixing carbon precursor with metal salts and performing one-step pyrolysis, the patent simultaneously forms the hard carbon matrix and distributes metallic particles throughout it. This integrated approach maintains manufacturing simplicity while achieving enhanced capacity above 300 mAh/g and improved insertion kinetics.
Solution Approach 2:
The patent creates composite materials by incorporating metallic components (tin, antimony, or their oxides) into the hard carbon structure during a single manufacturing process. This composite approach, achieved through co-pyrolysis, maintains the ease of conventional hard carbon production while significantly enhancing capacity and insertion kinetics through the synergistic combination of disordered carbon and reactive metal particles.
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 process results in anode materials with enhanced first discharge specific capacity and efficiency, suitable for commercial-scale production, and improved long-term electrochemical performance, particularly for sodium-ion batteries.
Implementation Method 1
heating the resulting mixture at 100°C. to 1500°C. to yield the material comprising the X/hard carbon composite
Data Source
AI summary
The invention relates to novel material comprising X/hard carbon composite and to a process for their preparation, the process comprising the steps: a) forming a mixture comprising i) one or more hard carbon-starting materials, ii) one or more starting materials which comprise one or more of the component elements of X, and optionally iii) one or more secondary carbon-containing materials; and b) heating the resulting mixture at 100° C. to 1500° C. to yield the material comprising the X/hard carbon composite; wherein X comprises one or more component elements selected from antimony, tin, phosphorus, sulfur, boron, aluminium, gallium, indium, germanium, lead, arsenic, bismuth, titanium, molybdenum, selenium, tellurium, cobalt and nickel and wherein X is present in an amount of at least 5% by weight of the material comprising the X/hard carbon composite.