Supercapacitor Research

$C=\varepsilon\varepsilon_0A/d

pore size (calculated)= 4000*PV/ SSA

crystallization degree of carbon materials

tanh

least squares method

0.91

$E=CV^2$

Artificial Neural Network Enabled Capacitance Prediction for Carbon-Based Supercapacitors

Shan Zhu, Jiajun Li, Liying Ma, Chunnian He, Enzuo Liu, Fang He, Chunsheng Shi, Naiqin Zhao

https://doi.org/10.1016/j.matlet.2018.09.028

MLBLUE

23 July 2018

6 September 2018

To serve as a service to customers and to allow for copyediting, typesetting, and review of the resulting proof before final publication.

The key component of a supercapacitor is the electrode.

Carbon is the most widely used material for the electrode in supercapacitors.

Some methods to improve the capacitance of carbon-based electrodes include increasing specific surface area, controlling pore structure, and introducing surface functional groups.

The advantage of using an artificial neural network (ANN) is that it can discover relationships between inputs and outputs of a system without a detailed understanding of the mechanisms involved.

One feasible method is to draw insights from a large amount of data.

Some factors that affect the performance of carbon-based supercapacitors include the materials' microstructures, surface functional groups, and testing details of practical application.

More than 300 published papers about carbon-based supercapacitors were collected to build the database.

ANN technology

specific surface area, calculated pore size, ID/IG ratio, N-doping level, voltage window

ANN

3.3%

almost 90%

its ability to recognize patterns in a series of input and output data without any prior assumptions about their nature and interrelations

small number of data points

by increasing the number of samples

assisting researchers in material science and application design

Electrochemical double-layer capacitors (EDLCs) and pseudocapacitors.

Chemical stability, less weight, low cost, good electric conductivity, and environment-friendly advantage.

KOH (potassium hydroxide).

Treating carbon sources with chemical agents and in situ doping using nitrogen-containing precursors.

Melamine is used as a nitrogen source in the synthesis of nitrogen-doped carbon sheets.

The resulting carbon sheets have a specific surface area of 1997.5 m^2 g^-1.

The mass ratio of glucose to melamine in the synthesis of N-doped carbon sheets is 1:1.

The heating rate during the synthesis of N-doped carbon sheets is 4 °C min^-1.

E = \frac{1}{2} CV^2

P = E \cdot t

C = \frac{I \cdot \Delta t}{m \cdot \Delta V} and C = \frac{m \cdot V \cdot I}{\Delta t \cdot \Delta V}

Cs = \frac{4I \cdot \Delta t}{m \cdot \Delta V}

The peak corresponds to the D-band and suggests the presence of disordered carbon structure.

The intensity ratio of D and G bands (ID/IG) is calculated to be 0.92, indicating a low crystallinity of the obtained NACS.

Three chemical elements of carbon, nitrogen, and oxygen can be detected.

The four different types of nitrogen functionalities observed in the high resolution N1s spectrum are pyridinic-N (N6) at 398.3 eV, pyrrolic-N (N-5) at 400.2 eV, quaternary-N (N-Q) at 401.4 eV, and pyridine-N-oxide (N-X) at 403.0 eV.

312 F g^-1

246 F g^-1

1. The sheet-like morphology provides a large exposed area to electrolytes and a short diffusion distance for electrolyte ions into the inner pore walls. 2) The hierarchical micro/mesoporous structure with high specific surface area, microporous volume, and uniform pore size distribution could accelerate ion transport process within the pore channels and provide abundant inner surface regions for ion accumulation. 3) Doping nitrogen groups increase the surface wetting characters, improve the conductivity of carbon materials, and introduce extra pseudocapacitance, thus further enhancing the capacity performance.

E = 0.5CV^2

C = \frac{Q},{V} = \frac{nF},{m} = \frac{m},{V}

NACS

Analyzing complex variables and predicting the capacitive properties of carbon-based supercapacitors.

melamine-assisted chemical blowing method

hierarchical porous structure, high nitrogen content, high specific capacitance (312 F g^-1), and good rate performance

20.2 Wh kg^-1 at 448 W kg^-1

3

The purpose of the chemical blowing process is to blow the melted glucose to form sheet-like precursors, together with doping nitrogen element.

The KOH chemical activation results in the decrease in thickness of sheets and the formation of numerous wrinkles on NACS.

The NACS material exhibits a type I isotherm due to the large N2 adsorption quantity in the low pressure region.

The specific surface area (SBET) of NACS is 1997.5 m2 g^-1, the micropore surface area (Smicropore) is 1220.9 m2 g^-1, the mesopore surface area (Smesopore) is 776.6 m2 g^-1, the total pore volume (Vtotal) is 0.94 cm3 g^-1, and the average pore diameter (Dp) is 2.73 nm.