Scope and Objectives

We aim to develop lithium ion batteries with higher energy/power densities (160Whkg-1/500 WKg-1), higher rate capabilities (C/5-1C discharge) and longer cycle life for various applications relevant to Indian Navy. Using optimised electrode materials, we will make 28V, 16 Ah battery module prototypes for underwater application relevant to NSTL, Vizag. The specific objectives are (i) Scale up the synthesis and optimize the performance of doped Li4Ti5O12 anode and activated carbon-doped LiMn1.5Ni0.5O4 spinel hybrid cathode. (ii) Fabricate 18650 type cell using optimized electrodes. (iii) Develop battery module (28V, 16Ah) along with protection circuit and BMS. (iv) Real field testing and bench-marking of the indigenous battery developed.

Deliverables

The main deliverable are (i) We will make about 150 numbers, 2Ah, 18650 cylindrical cells with specific energy in the range of 140 to 250 WhKg-1 and specific power in the range of 500-750 WKg-1. Typically, doped Li4Ti5O12-activated carbon-LiMn1.5Ni0.5O4 spinel hybrid and carbonaceous anode-activated carbon- LiMn1.5Ni0.5O4 spinel hybrid electrode combinations will be used in making these batteries. Liquid organic electrolyte will be used in making these cells. Charge-discharge, cycleability, and rate capability characteristics of these cells will be documented and bench-marked with commercial cells. (ii) These cells will be connected in series (to increase voltage) and parallel (to increase capacity) to yield 28V 16 Ah battery. Suitable protection circuit and battery management system will be developed for efficient cell balancing and bench-marked with commercial counterpart. (iii) Battery modules with protection circuit and battery management system will be packaged in a water sealed container and the charge-discharge, cycleability, and rate capabilities characteristics of the developed module will be documented and bench-marked. Additionally, environmental tests for these battery modules will also be documented. Two battery modules will be delivered to NSTL. (iv)The battery module will be used in underwater target device and its performance will be documented and compared with similar target device powered by AgO-Zn batteries.

Videos

Scientific Output

1. Upscale electrode materials synthesis and characterization: We have synthesized about 3.0 Kg LiMn1.5Ni0.5O4 and 1.8 Kg Li4Ti5O12 (LTO) anode powders for cell fabrication. As shown in Fig. 4 (a) we have achieved 150 mAh/g discharge capacity for C coated LTO with decent rate performance (Fig. 4(b)). However, as shown in Fig. 4(c), cycleability of LTO powder needs to be improved further. Figure 5 shows (a) the charge-discharge and (b) rate performance of up-scaled LiMn1.5Ni0.5O4 cathode in half cell configuration. The achieved discharge-capacity is about 105 mAh/g and it performs reasonably well at 1C discharge rate. The batch to batch variation of LMNO is found to be in the range of 105-125 mAh/g. 2. Cell fabrication: We are optimizing the anode and cathode loading (in the range of 10-30 mg/cm2) on copper and aluminum current collector (80 cm x 55 cm). Using NSTL facilities we have fabricated LTO-LiMn2O4 (LMO) pouch cells. Few MCMB-LMNO pouch cells are also fabricated. Figure 6(a) shows the charge-discharge characteristics of LTO-LMO pouch cell. As shown in Fig. 6(a) the fabricated pouch cells yield 2.4V nominal voltage and 1.7Ah discharge capacity at C/5 rate. Figure 6(b) shows reasonably good rate performance of the fabricated cells until 1C rate. 3. Protection circuit, BMS and battery module: Prototype protection circuit and BMS (version 1) has been tested with 48V 5Ah commercial battery pack (Future Hitech Ltd.) used in E-scooter. A video clip in this regard has been uploaded in you tube (link: https://youtu.be/hB5SajCF-JA ). The photograph of 28V, 5 Ah (7S2P) battery pack and BMS system are shown in Fig. 7(a) and (b) respectively. Figure 8 shows the BMS monitors the voltage, current, state of charge (SOC) and temperature of individual cells and the pack. The cell balancing during charge mode is also represented in Fig. 8.

Results and outcome till date

Presently we are facing some problem with our dry room. Hence, cyclindrical cells could not be made using the optimized electrodes. However, we have modified the design of the battery pack and BMS enclosure. The 2nd version of the battery enclosure is shown in Fig. 1. In this battery pack a small fan has been installed for efficient cooling. The photograph of the assembled CAD design is shown in Fig. 2. Now we are fabricating the 2nd version of the battery pack. Both these battery pack will be taken to NSTL for vibration and thermal cyling tests. Subsequently these battery packs will be taken to Amara Raja Batteries Limited for charge discharge studies.

Societal benefit and impact anticipated

The propulsion of high speed underwater weapon requires power from battery at 10-20C rates whereas low speed vehicles and stationary articles require power at C/5 to C/10 rates. To test the extended performance of underwater weapon, due to the non-availability of moving targets (ships/submarines), simulated targets are deployed in practice. These simulated targets require high energy density batteries for extended duration to cater for their deployment and subsequent recovery after the sorties is completed. Existing batteries (AgO-Zn) survives only up to 50 cycles. High energy and high power density lithium ion rechargeable batteries could provide more service cycles ( more than 500 cycles) and will have life period more than 3 years. However, such lithium ion rechargeable battery is not available indigenous. In view to this, indigenous technology for high energy and high power density lithium ion batteries must be developed for the use of Indian Navy.

Next steps

Using commercial cells we will make a 28V 16 Ah battery module and pack it in a water sealed container with developed BMS. Reliability testing of the battery pack will involve subjecting the pack to vibration and temperature reliability tests. These tests will be conducted at the NSTL facility in Vishakhapatnam, on a vibration test platform subject to standard suite of amplitude and frequency of vibrations. The integrity of the pack will be examined before and after each test. This will be followed by temperature cycling tests in the environmental where the temperature will be varied from 0 to 50 deg C with the battery at different states of charge. The thermal characterization of the pack will involve a two-pronged approach comprising of system level modeling using ANSYS which will be validated through tests. The experimentally validated model will then be used to evaluate different "what-if" scenarios with focus on identification of hot spots and mitigation strategies for the same through novel cooling approach.

Publications and reports

Following peer reviewed journal papers are published:

1. Investigations on the electrochemical characteristics of rechargeable MCMB-LiNi0.5Mn1.5O4 pouch cells, Kirtan Sahoo, Jayram Majhi, Arijit Mitra, A. Srinivas Kumar, S. B. MajumderJ. Electrochemical Society, 166 A342-A352 (2019)

2. Fabrication and Investigation of MCMB-LiNi0.5Mn1.5O4Pouch Cells for High Energy Density Lithium ion Batteries: Indigenous Efforts and Challenges for Realization, Kirtan Sahoo, G. D. Prasad, K. Jagdish, A. Srinivas Kumar, Subhasish Basu Majumder, Transaction of Indian Institute of Metals Manuscript# TIIM-D-18-01107R1 (Accepted).

Patents

Nil

Scholars and Project Staff

i. Mr. Rajwardhan Pawar, JRF (cell fabrication), since December 22, 2017
i.i Mr. Jyotirmaya Sahoo, Ph.D EE Department (BMS development), since January 25 2018, w.e.f 2-01-2019 he has been enrolled as a Ph.D student in Electrical Engg. Dept. IIT Kharagpur.
iii. Mr. Proloy Biswas, JTA, since January 01 2018 iv. Mr. Raswa Om Prakash, JTA, since January 01, 2018

Challenges faced

Other information

Copper tab welding machine is malfunctioning. Its setting needs to be adjusted. Spot welding is not functioing properly. We are working on this.