Scope and Objectives

Identify suitable materials for sodium ion cell and super capacitors, keeping in view performance and cost Generate IPR on new materials Simulation based design of sodium ion cell, keeping in view the thermal management Fabrication of sodium ion pouch cells (2.7-3.5 V, 2.7 Ah) and super-capacitors stack (48 V, 2 A, 30-60 s) Development of energy management system (EMS) for sodium ion cell/supercapacitor pack Fabrication of NIB-Super capacitor pack (around 6A, 48V, 11 Ah, 280 W, 1040 Wh) and field test on a E-scooter (Motor: around 48V, 250 W, 5.2 A)

Deliverables

D1: Half-cell optimization of electrode materials culled from literature: (in 1 - 1.5 years) Cathode: Sp. capacity of 120-150 mAh/g C/20 rate, Cycle life - 50 cycles with more than 80% or more specific capacity retention.Anode: Sp. capacity of 200 mAh/g C/20 rate, Cycle life - 50 cycles with more than 80% specific capacity retention. D2: Novel electrode material optimization in half-cells: (in 2 - 2.5 years) Cathode: Specific capacity of 150-175 mAh/g C/20 rate, Cycle life - 200 cycles more than 80% or more sp. capacity retention.Anode: Specific capacity of 240 mAh/g C/20 rate, Cycle life - 200 cycles more than 80% sp. capacity retention. D3: Full Cell: (in 3 years) Na-ion pouch cell with energy density of 250 Wh per kg (C/20) of electrodes (anode+cathode) will be delivered. Cycle life - 100 cycles more than 80% sp. capacity retention. D4: Fabrication of Supercapacitor for the hybrid pack: (in 2.5 - 3 years) Voltage: 48 V, Current: 2A, Short Duration: 30-60 s D5 (Final outcome): Delivery of NIB-Supercapacitor pack (around 6A, 48V, 11 Ah, 280 W, 1040 Wh) and field test on a E-scooter (Motor: around 48V, 250 W, 5.2 A) (3.5 - 4 years)

Videos

Scientific Output

Major achievements Both cathode and anode half cells have been prepared and tested. Patent for anode material is under process. 3 journals have been published.

Results and outcome till date

Carbon anode - Nitrogen doped and undoped hierarchical mesoporous carbon balls, having sizes in both micron and nano range, were synthesized using a single step hydrothermal method, which is significantly cost effective. All previous work has shown increase in defect and conductivity as a reason behind increase in specific capacity due to nitrogen doping. This work has shown volume expansion as one of the factors along with defects and conductivity as a reason for increase in capacity due to nitrogen doping. As an anode of Na ion cells, the electrochemical performance of the nitrogen doped nano-sized mesoporous carbon balls is among the best ones reported till date. Nitrogen doping had the following effect on the Na intercalation behavior 1. Specific gravimetric capacity increased. 2. Capacity retention improved, particularly for the case of nano mesoporous carbon balls (N-NCB). This was due to the significant reduction in the volume expansion associated with the Na intercalation, as revealed by the density functional theory based computation. 3. Nitrogen - doping tends to suppress the solid-electrolyte interface (SEI) formation and enhances the charge transfer rate. The electronic conductivity of the carbon balls increased. The increase is also evidenced by the density of state (DOS) plot of undoped and nitrogen-doped amorphous carbon structures, which were generated using Density Functional Theory based computations. Related patent for the above work is under process. Effect of aliovalent atom (V5+) in NNMO prepared by solid state and co-precipitation method is carried out. Full cell has been made using this cathode with carbon anode with 100 Cycles. Because of its stability and safety nature, carbon coated Sodium vanadium phosphate (NVP) was prepared as cathode for the battery we have got a stable capacity till 50 cycles for half cell, while addition of reduced graphene gives a better cycle life. For different cathode chemistries i.e. lithium ferrous phosphate, lithium manganese oxide and lithium cobalt oxide of Li-ion cylindrical battery, the temperature distribution during charge/discharge cycles is examined through simulation. All the chemistries behave almost identically with insignificant difference in temperature distribution amongst them, which indicate we need new modeling tool to capture the effect of chemistry on the thermal performance backed up by experiments. Maintaining a form factor, the effect of the constituents for Na-ion batteries will be tested accordingly as the details are available for the other work-packages. Further, the suitable thermophysical properties will be identified for the coolant to be used for the optimal thermal management. Energy Management System (EMS) is developed for lightweight electric vehicle, where Modular Multilevel Converter (MMC) based power electronics topology is used. This topology will help to feed the power to motor of EV from battery pack and it will charge the battery pack at the time of regenerative breaking. The simulation part is completed now hardware for the same is on progress.

Societal benefit and impact anticipated

Pb-acid batteries (PAB) are not suitable for electric vehicles due to their poor specific energy density. Lithium ion batteries (LIB), although having much higher specific energy density, are not cost effective and thus have not replaced PAB for majority of electric vehicles in India. Also India will have to totally depend on other countries which have significant lithium ore. Alternatively, sodium ion batteries (NIB) can have specific energies at par with lithium ion batteries and are significantly cheaper than LIB with sodium in abundant. Therefore, the project aims at run an E-vehicle using indigenously developed NIB-supercapacitor pack. Since there is no commercially available sodium ion cells in the market or battery management system for such batteries, our project team is exploring indigenous development of sodium ion cells, battery management system and thermo-mechanical simulations at different length scales.

Next steps

The next steps involved will be making a pouch cells with best performance available at coin cell level. Optimization studies using computational techniques and developing the electrical management system.

Publications and reports

The following peer reviewed publications have so far been resulted from the work executed. Nayak, Debasis, Sudipto Ghosh, and Venimadhav Adyam. Thin film manganese oxide polymorphs as anode for sodium-ion batteries: An electrochemical and DFT based study. Materials Chemistry and Physics 217 (2018): 82-89. https://doi.org/10.1016/j.matchemphys.2018.06.065 Janakiraman, S., O. Padmaraj, Sudipto Ghosh, and A. Venimadhav. A porous poly (vinylidene fluoride-co-hexafluoropropylene) based separator-cum-gel polymer electrolyte for sodium-ion battery. Journal of Electroanalytical Chemistry 826 (2018): 142-149. https://doi.org/10.1016/j.jelechem.2018.08.032 Khalifa, Mohammed, S. Janakiraman, Sudipto Ghosh, A. Venimadhav, and S. Anandhan. PVDF/halloysite nanocomposite based non wovens as gel polymer electrolyte for high safety lithium ion battery. Polymer Composites (2018). https://doi.org/10.1002/pc.25043

Patents

1 Patent applied, Titled "An improved process of syntheses of nitrogen doped nano sized mesoporous spherical hard carbon synthesis and its application thereof as anodes Na ion cells".

Scholars and Project Staff

1. Dr. Vijay Prakash (Project Staff) has joined as Post Doctorate from June 2017 till date. 2. Ms. Ananya Kumar (Project Staff) has joined as JRF and enrolled in PhD programme from Jan 2018 till date. 3. Mr. Janakiraman (Institute Scholar) SRF from March 2017 till date 4. Mr. Debashish Nayak (Institute Scholar) SRF from March 2017 till date 5. Mr. Ashutoosh (Institute Scholar) SRF from March 2017 till date 6. Ms. Rasmita Biswal (Institute Scholar) SRF from March 2017 till date 7. Mr. Pavan kumar (Institute Scholar) JRF from March 2017 till date 8. Mr. Jay Kishan (Institute Scholar) JRF from March 2017 till date 9. Ms. Jeemut (Institute Scholar) JRF from March 2017 till date 10. Ms. Debanjana (Institute Scholar) JRF from March 2017 till date Other than this more two Institute Scholars from IIT Kanpur are working in the project

Challenges faced

Other information