Battery Technologies for electric vehicles
BY D GEETHALAKSHMI
Globally transportation sector is passing through a paradigm shift from conventional internal combustion engine vehicle to electric vehicles. Electro mobility has gained global attention in the light of fast depletion of fossil fuels and impact of transportation on environment due to increased GHG emission.
In a Battery Electric Vehicles (BEV), battery is considered as the heart of electric vehicles because,
– The range of the vehicle depends entirely on the battery.
– It is the heaviest electrical component.
– It is the most expensive electrical component.
The size of the battery employed in cars generally varies between 20kWh to 40kWh and upto 60kWh for high end cars. For buses it is in the range of 90kWh to 150kWh.
Selection of Batteries
Among the different types of batteries available in the market, few of battery technologies which have gained popularity in the EV markets and commercially employed are
- Lead acid batteries
- Nickel Metal Hydride Batteries (NiMH)
- Lithium-ion batteries (Li-ion)
Lead acid batteries are in existence for a long period of time and have many proven installations in two-wheeler EVs. Lead acid batteries are heavier and take up more volume to achieve the same amount of range compared to the other battery technologies. Due to their low energy & power density, lead acid batteries are not popular in 4 wheeler vehicles.
NiMH batteries initially dominated in hybrid electric vehicles (HEVs) market, but due to its heavy weight and outdated technology lost its market share considerably.
Li-ion is a mature technology and it is currently being used all over the world and has proven installations in 2-wheeler, 4-wheeler EV and also in heavy vehicle like buses and trucks. Li Ion batteries have relatively higher energy and power density and have high electrochemical potential (>3Volts). These qualities of Li-ion batteries make it suitable for Electric vehicle application. Good cycle life, low self-discharge (less than half of Ni-MH), fast charging capability are other advantages of Li-ion batteries.
Among the different types of Li-ion batteries such as Lithium Nickel Manganese Cobalt Oxide (NMC), Lithium Nickel Cobalt Aluminum Oxide (NCA), Lithium Iron Phosphate (LFP), Lithium Manganese Oxide ( LMO), Lithium Titanate (LTO), Lithium Cobalt Oxide (LCO) and lithium polymer, currently the most widely used types in EV are NMC , LFP and NCA because of their higher current density, large number . of cycles and cycle time.
Significant research is under way for the development of several future cell chemistries which are expected to outperform contemporary Li-ion cells. Chemistries which are in the pipeline that could enable the future of battery technology are Lithium metal (Li metal) batteries, Solid State batteries (SSB), Lithium-sulphur (Li-S) batteries and Lithium-air (Li-air) batteries.
Battery raw materials and its availability
The key constituents of a Lithium Ion battery are Lithium, Cobalt, Manganese and Nickel which forms the cathode and Graphite which is used as anode. Lithium occurs in the form of compounds in pegmatitic minerals. Lithium is mainly found in South American countries with 55% global deposits located in Bolivia, Argentina and Chile which make up the lithium triangle. In Asia, China has the highest share with nearly 17% of the global reserves. Apart from Lithium, Cobalt is a critical raw material in the Li Ion battery due to its high economical impact, high supply risk and high composition used. About 51% of the global reserves of Cobalt is found in Democratic Republic of Congo a region that has not been stable in the past.
Currently India imports Li Ion batteries mainly from China, South Korea and Japan. To meet the inspirational goal of 30% EV by 2030, it is estimated that the India would need around 20 giga factories for manufacturing Li-Ion batteries.
The key challenges faced to develop ”The make in India” battery domestic market are low mineral reserves, lack of technological capability, lack of coordination among stake holders and investment risk. India does not have reserves of some of the major raw material which includes Lithium, Cobalt and Nickel. Thus it is expected that India would build international partnerships and ventures to secure access to key minerals.
Cost of the battery is set to impact on the EV growth. Currently, the cost of the battery makes up to nearly 50% of cost of Electric Vehicle. Though, in the three-year period from 2014 to 2016, battery costs have fallen steeply through various process improvements and scale effects, cost of BEV are not on par with conventional internal combustion engine (ICE) vehicles. However, If battery cost continue to reduce further, they will reach 125$ -150$ by 2025 which makes EV price competitive with conventional vehicles.
The services that TCE could offer includes , developing mining infrastructure for extraction of raw materials for batteries, engineering consultancy for charging infrastructure including private and public charging and engineering consultancy for setting up the infrastructure for new and augmentation of battery manufacturing plants.