Advanced Carbon Products

A leading centre in India dedicated to research in both pure and applied science of Carbon with principal motives i) to develop the process technology of newer carbon products which hold strategic importance and are not available to the country at any cost, ii) to develop products which can be made cost-effective by innovative process suitable to available infrastructure, expertise and resources in India, iii) to promote overall growth of carbon science and technology in the country through sustained R&D, research publications, patents, technology transfer, consultancy to industry, national labs etc.

The group is presently engaged in several National and International collaborative projects to develop specific products for clean energy generation and strategically important Advance carbon materials . Some of the ongoing projects are :

  • Innovation solutions for solar energy storage (Li-ion Battery) -   CSIR-TAPSUN
  • Development of continuous carbon nano fibres by electro spinning-   DST
  • A novel way to reduce Platinum metal loadings in a carbon nano-composite electrode to produce low cost-high efficiency commercially viable  Polymer Electrolyte Membrane(PEM) fuel cells-   AISRF, Indo-Australia
  • Development and demonstration of Polymer Electrolyte Fuel cell (PEFC) for stationary Applications-    CSIR-NMITLI
  • Development of high temperature silicon carbide material suitable for microwave  susceptor application-    DST
  • Synthesis and development of graphene based polymer composites: its application in polymer electrolyte membrane fuel cell-    DST
  • Development  of  Advanced  Materials  for  Next-Generation  Energy-Efficient Devices (D-NEED) ,   CSIR-Network under XII FYP

 

Some of the significant achievements during the last one year are reported here.

Synthesis of Single layer  graphene by re-exfoliation of Expanded Graphite

Graphene (Gr ) is a transparent single atom-thick planar sheet of sp2 bonded carbon atoms that are densely packed in a honeycomb crystal lattice. It is regarded as the “thinnest material in the universe” with tremendous strength similar or slightly greater than CNT, but much higher than steel. 

Development and demonstration of polymer electrolyte membrane Fuel Cell (PEMFC) stacks for stationary applications 
Fuel cells are electrochemical devices that convert chemical energy of the reactants ( hydrogen and oxygen)  directly into electricity and heat with high efficiency. Since the only by-product is water it is highly environment friendly source of energy. CSIR under the NMITLI mission has initiated a program involving networking of three laboratories CSIR-NPL, CSIR-NCL and CSIR-CECRI to develop and demonstrate a PEM fuel cell stack using all indigenous components. NPL has successfully developed two important carbon components of the fuel cell viz. Porous  conducting carbon paper and composite bipolar plate matching the performance of commercially available components. A 1kW polymer electrolyte membrane fuel cell (PEMFC) stack using NPL porous conducting carbon paper and NPL carbon composite bipolar plates is functional at CECRI.

                Fig.1 A 500 W PEM fuel cell stack with  all indigenous components
                              (b) NPL bipolar plate (c) Porous conducting carbon paper

Besides continuous supply of these two components to CECRI, R&D is continuing to further improve the quality of the products and also carry out long term durability tests.

NPL technology for porous conducting carbon paper goes commercial

  • Carbon paper electrode has a critical role in the proper functioning of fuel cell. The carbon paper technology has been successfully developed at NPL and the process know how has been transferred to Ms. HEG, Bhopal.
  • Following NPL technology M/s HEG has now come up with the carbon paper equivalent in performance with the commercial standard Toray paper of Japan (fig.2) and meeting the requirement of carbon paper for India’s fuel cell program.

Fig. 2  Comparative performance of PEMFC with HEG and Toray carbon paper

An improved high performance  Carbon Paper For cost efficient PEM  Fuel Cell

  • A novel technique has been used to develop CNT incorporated carbon paper to achieve high fuel cell performance without any additional set up or cost. The peak power density obtained from improved NPL carbon paper shows an increase of nearly 25% as compared to the commercially available standard Toray carbon paper (Japan) tested under similar conditions as shown in fig. 3a.
  • Even after  40% reduced Pt loading the performance is better than Toray carbon paper thus making Indian technology cost competitive (Fig.3b). The performance evaluation was done at CSIR-CECRI, Chennai.
Fig.3a.Comaparative performance of PEMFC using NPL and Toray paper (Catalyst; 0.5 mg/cm2 Pt)Fig.3b Comparative performance of PEMFC using NPL and Toray paper ( Catalyst: 0.3 mg/cm2 Pt)

 


Development of Carbon based Anodes for Li-ion Batteries

With increasing global energy demands and ill effects of using hydrocarbon fuels, electrochemical cells/ batteries acts as a convenient form of energy storage that provide portability for chemical energy storage and its conversion to electrical energy by electrochemical oxidation and reduction reactions which occur at the electrodes. 
Li-ion batteries (LIB) are preferred over other systems because of long cycle life, broad temperature range of operation, low self discharge rate high performance in terms of capacity and energy density.
 Anode is the most critical in the proper functioning of the cells & acts as a host for the Li ions. Not only should it have a high Li insertion capacity, but should allow the intercalation/ de-intercalation of Li with ease while retaining its structural stability for high cycleability and longer cell life.

Novel free standing anode materials have been developed at NPL, New Delhi with high aspect ratio carbon materials that include- Anode for Li-ion battery has been made from phenolic resin reinforced carbon fiber, followed by molding and heat treatment .The electrode gives consistent performance for more than 500 cycles.

 

Carbon fiber paperDischarge Capacity- 200mAh/g, No. of cycles > Glowing solar lamp with Li-ion battery prepared from NPL anode and CECRI cathode

Free standing Multiwalled carbon nanotube (MWCNTs)based anode-

Flexible MWCNT based Cyclic performanceGlowing solar lantern with Li-ion battery prepared from NPL anode and CECRI cathode

 

MWCNTs have been synthesized at NPL using Chemical vapor deposition technique. Free standing, flexible anode for Li-ion battery has been prepared which shows increasing capacity with successive cycles.

The studies have been carried out under the CSIR-TAPSUN project “Innovative Solutions for Solar Energy Storage”.

Dispersion and alignment of CNTs and development of CNT reinforced composites:
    The studies were continued under the DRDO Sponsored project to carbon nanotubes based High Performance composites for applications in Airframes, Heat shields, Rocket Motor Casings and futuristic missile system. Experiments were performed to optimize the dispersion conditions of MWCNT in the epoxy resin matrix. The maximum value of flexural strength which could be achieved for CNT/epoxy composites with existing dispersion technique was ~ 115 MPa and flexural modulus ~2-3 GPa with 0.5-1% CNT loading. It was also observed that amine functionalized tubes shows improved better properties than the acid functionalized tubes based composites. The improvement in the mechanical properties of the resin by 60% following reinforcement of CNTs provides a useful insight to use such modified resin for carbon fibre/CNT-Epoxy mulltiscale composites. The values fall in the range of the global trend.

Studies on the alignment of CNT in polymer matrix
Preliminary experiments on the optimization of processing parameters to draw fine nano meter dia. fibres with different polymer systems are being tried out. The schematic of the  spinning unit is shown in figure 4. PAN based polymer nanofibers with diameter in the range 100-200nm have been achieved. Figure.5 (a-e) shows the SEM micrograph of electrospun nanofibers with drawn with different spinning conditions e.g. varying tip to collector distance, collector drum speed with constant applied voltage and PAN concentration. At tip to collector distance  of 10 cm nanofibers diameter is in the range of (100-200) nm.

Fig.4  Schematic diagram of Electrospinning

(a) (b)(c)

 

(d) (e)

Fig 5. SEM micrograph electrospun fiber drown from 5 wt % of PAN solution at different tip to collector distance and rotational speed of cylindrical collector (a) 10 cm (b) 15 cm (c) 20 cm, at speed 1000 rpm and (d) 10 cm (e) 20 cm, at speed 2000 rpm

Carbon Nanotube incorporated light weight carbon foam
NPL has developed carbon foam with sponge-like rigid engineering material having low density(0.5g/cc), large surface area with 70% porosity and open cell wall structure as shown in Fig.  6

Fig.6 Microstructure of graphite foam developed at NPL

 

Applications

  • EMI SHIELDING Material for Aerospace Applications
  • ANODE MATERIAL for Lithium ion Batteries
  •  Light weight Electrode for  Lead Acid Batteries 

Advantages

  •  Significant weight reduction
  •  Size reduction of battery
  •  Better current collection efficiency
  •  Easy recycling
  • Higher energy & power densities

1. Carbon Form  Light Weight Engineering Material

Carbon foams are next generation sponge-like high performance structural engineering materials in which carbon or graphitic ligaments interconnected to each other, and have recently attracted a lot of attention owing to their potential applications in various fields.  It possesses low density, large surface area with open cell wall structure, high specific thermal/electrical conductivity, thermal and mechanical stability. The electrical conductivity of CF derived from different organic and inorganic precursor can be tailored by controlling processing parameters. NPL is engaged in developing the carbon foam from coal tar pitch by simple and low cost sacrificial template technique, in which the polyurethane foam is used as template.  We at NPL putting continues effort to improve the mechanical, thermal, electrical and Electromagnetic interference (EMI) shielding effectiveness of carbon foam to use as shielding and thermal interfacing material  in aerospace and aircraft  to protect  from electromagnetic radiation as well  avoid the electronic systems from overheating. To improve the overall properties of carbon forms two approaches are adapted i.e. incorporating or decorating carbon foam by nanosize organometallic (ferrocene) compound and by carbon nanotubes. In another approach, carbon foam has been decorated with multi-wall carbon nanotubes (MWCNTs) by two different routes to improve its electromagnetic interference (EMI) shielding effectiveness and mechanical properties. Apart from EMI shielding material it will be used as anode material for lithium ion batteries and  light weight electrode for lead acid batteries.
Figure 6  shows the effect of different content of organometallic compound on the electromagnetic interference shielding of carbon foam.  The EMI Shielding effectivness  -81 dB of was achived with 10 wt % of ferrocene.  Beside, compresive strenght, electrical/thermal conductivity and thermal stability also increases. 

Figure 6: (a) carbon foam heat treated at 2500°C, (b) EMI shielding effectiveness of ferrocene
incorporated carbon foam.

Applications

  • EMI SHIELDING Material for Aerospace Applications
  • ANODE MATERIAL for Lithium ion Batteries
  •  Light weight Electrode for  Lead Acid Batteries 

Advantages

  •  Significant weight reduction
  •  Size reduction of battery
  •  Better current collection efficiency
  •  Easy recycling
  • Higher energy & power densities

2. Continuos polymer and carbon nanofiber by Electrospinning
Electrospinning is a simple and versatile method for producing nanofibers from verity of materials with fiber diameter ranging from several micrometers down to ten nanometers.  In this technique, polymer solution electrospun under application high electric filed.  The electrospun apparatus consist of syringe pump, DC high voltage and rotating cylindrical collector.  The electrospun polymer nanofiber of different diameter spun from polyacrilonitrile solution of different concentration.  The diameter of polymer nanofibers depends upon processing parameter and polymer solution properties. Figure 7, Electrospinning apparatus and PAN based electrospun polymer, stabilized and carbon nanofibers. The diameter of PAN polymer nanofiber varies between 500-600 nm, on oxidation-stabilization nanofiber diameter reduced to 500-550 nm.     During carbonization, nanofiber diameter decreases to 300-400 nm due to conversion of polymer nanofibers into carbon nanofibers, as a consequence evolution of volatile by product. Apart from, we are working on nanofibers derived from biodegradable polymer for application in drug delivery and enzyme immobilization. 

Figure 7: Electrospinning Apparatus and SEM micrographs electrospun nanofibers.

The carbon nanofibers have number of applications different areas of science and technology such as super-capacitors, filters, nanocomposites, catalyst supports for rechargeable batteries or fuel cell, and optoelectronics.

3. Single /double layer Graphene synthesis
 Studies were carried out under the department of science and technology project on the synthesis of graphene by chemical route and chemical deposition technique. The new approach was adapted to deposit single or multiple graphene layers on a copper foil . An experimental set up was designed and fabricated to grow graphene sheet on any substrate and is shown in Fig.8 Experiments are in progress to grow large size high purity graphene sheets followed by characterization by Raman spectroscopy.

Figure 8 Experimental setup for the growth of  graphene by CVD .

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