Phosphorus-Doped Carbon Anodes for Stable High-Capacity Storage
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Solution Overview
Problem
Existing carbonaceous materials used as negative electrodes in power storage devices face challenges in achieving high discharge capacity and current efficiency, particularly in maintaining capacity after repetitive charging-discharging.
Innovation Solution
A carbonaceous material with specific elemental content ranges, including nitrogen (1.0% by mass or more), hydrogen (0.1% by mass or less), and phosphorus (0.5% to 2.0% by mass), is developed. This material is produced through a method involving the mixing of sugar skeletal compounds with nitrogen- and phosphorus-containing compounds, followed by heat treatment in inert gas atmospheres at specific temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional carbonaceous materials are used as negative electrode, then the electrode can be manufactured with standard composition, but the discharge capacity per weight and current efficiency are insufficient
Solution Approach 1:
The invention changes the elemental composition parameters of the carbonaceous material by precisely controlling nitrogen content (1.0-10.0 mass%), hydrogen content (0.1-5.0 mass%), and phosphorus content (0.5-2.0 mass%). This parameter optimization resolves the contradiction by achieving both high discharge capacity per weight and high current efficiency simultaneously, rather than accepting the insufficient performance of conventional materials with standard composition.
Solution Approach 2:
The invention creates a composite carbonaceous material containing multiple elements (C, N, H, P, and optionally O, S, B, F) with specific content ratios. This composite approach allows the material to achieve superior electrochemical performance with discharge capacity per weight of 400 mAh/g or more and current efficiency of 70% or more, resolving the limitations of conventional single-element or simple composite carbon materials.
2Quantity of substance
If plant-derived carbon materials are calcined to create porous structure, then charge/discharge capacity is improved, but the material requires additional processing steps and precise compositional control
Solution Approach 1:
The invention incorporates nitrogen-containing compounds and phosphorus-containing compounds into the carbon source material before calcination. This preliminary action ensures that the desired elemental composition (N: 1.0-10.0 mass%, P: 0.5-2.0 mass%) is achieved during the carbonization process itself, rather than requiring subsequent complex processing steps to adjust the composition after porous structure formation.
Solution Approach 2:
The invention merges the porous structure formation with the elemental composition control into a single calcination process. By combining carbon source material with nitrogen-containing and phosphorus-containing compounds before calcination, the process simultaneously creates the desired porous structure for high charge/discharge capacity and achieves the target elemental composition, reducing the number of separate processing steps.
3Quantity of substance
If nitrogen content is increased to improve discharge capacity, then capacity is enhanced, but hydrogen content must be strictly controlled to maintain current efficiency
Solution Approach 1:
The invention establishes specific parameter ranges for multiple elements simultaneously: nitrogen (1.0-10.0 mass%), hydrogen (0.1-5.0 mass%), and phosphorus (0.5-2.0 mass%). This multi-parameter optimization approach allows nitrogen content to be increased for enhanced discharge capacity while maintaining strict control over hydrogen content to preserve current efficiency, resolving the contradiction through coordinated parameter management rather than isolated control.
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 carbonaceous material demonstrates high discharge capacity per weight and high current efficiency, maintaining a high discharge capacity even after repetitive charging-discharging, thus enhancing the overall performance of power storage devices.
Implementation Method 1
heat-treating the mixture in an inert gas atmosphere at 500 to 900° C. to obtain a carbonized product
Implementation Method 2
heat-treating the thus crushed and/or classified carbonized product in an inert gas atmosphere at 1200 to 1600° C. to obtain the carbonaceous material
Data Source
AI summary
The present invention relates to a carbonaceous material having a nitrogen element content of 1.0% by mass or more and a hydrogen element content of 0.1% by mass or less, both measured by element analysis, and a phosphorus element content, measured by X-ray fluorescence analysis, of 0.5% by mass or more and 2.0% by mass or less.