ELECTRIC VEHICLES AND BATTERIES

Posted on April 26,2020

Optimization of battery technology in Electric Vehicles and their implementation in India.

Introduction

Vehicle, a name coined from a Latin word, has defined the means of movement both in past and new world. You can hardly imagine a world without vehicles. It is used for commuting needs; it is used as a symbol of status and as a goods transport tool. Vehicles consist of many parts which helps them to run. The heart of the vehicle is an engine which converts one form of energy into mechanical energy. Engines are mainly of two types: Internal combustion engine which burns fuel to create heat which is then used to do work and Electric motors which deliver power to the wheels by taking powers from rechargeable batteries. In the modern world, most of the people have vehicles, and most of them are internal combustion engines which use petroleum to run, which is in limited quantities on earth. So there is a need for electric vehicles which run on rechargeable batteries which do not use any fuel and have many more advantages above internal combustion engine running vehicles.

What is Electric Vehicle?
Electric Vehicle is any vehicle propelled by an electric drivetrain taking power from the rechargeable battery or from a portable electrical energy source which is manufactured for use on public roads.
What is inside an Electric Vehicle?
All Electric Vehicles have an electric motor instead of an internal combustion engine. Vehicles use a large traction battery pack to power the electric motor. As it runs on electricity, the vehicle emits no exhaust from the tailpipe and does not contain any fuel components.
KEY COMPONENTS OF EV’s-
  1. Auxiliary Battery- It provides electricity to power vehicle accessories.
  2. Charging port- It allows the vehicle to connect to an external power supply to charge the traction battery pack.
  3. DC/DC converter- This device converts higher-voltage DC power from the traction battery pack to the lower-voltage DC power needed to run vehicle accessories and recharge the auxiliary battery.
  4. Electric Traction motor- They use power from the traction battery pack to drive the wheels of the vehicle.
  5. Onboard charger- It converts the AC electricity supply via charging port into DC power for charging the traction battery. It also monitors battery characteristics such as voltage, current, temperature and state of charge while charging the pack.
  6. Power electronics controller- This unit manages the flow of electrical energy delivered by the traction battery, controlling the speed of the electric traction motor and the torque it produces.
  7. Thermal System- It maintains the proper operating temperature range of all the of EV.
  8. Traction Battery Pack- It stores energy which is used by the electric traction motor.
  9. Transmission- It transfers mechanical power from the electric traction motor to drive the wheels.
Components of Electric Vehicle
Advantages of EVs

    There are a lot of advantages of electric vehicles over conventional fuel vehicles-

  1. Electric vehicles run on electricity so do not require any fuel. Fuels which are limited in quantity are also saved.
  2. Electric vehicles are fuelled very cheaply, and the government also provides subsidies on electric vehicles.
  3. Electric cars are 100 per cent eco-friendly as they run on electrically powered engines. It does not emit toxic gases or smoke in the environment as it runs on clean energy sources.
  4. Electric vehicles have low maintenance cost as they run on electrically powered engines and hence there is no need to lubricate the engines.
  5. Electric vehicles reduce noise pollution as they are much quieter. Electric motors are capable of providing smooth drives with high acceleration over long distances.
Disdvantages of EVs

    With advantages, there are some downsides of electric vehicles too-

  1. Electric fueling stations are still in the development stages. There are not enough charging stations present to fulfil the needs.
  2. While it takes a couple of minutes to fuel gasoline-powered vehicles, an electric vehicle takes about 5-6 hours to get fully recharged.
  3. Electric vehicles are limited by range and speed.
  4. Batteries are required to be replaced every 3-10 years depending on type and usage of the battery.
  5. Some basic models are still expensive.
TYPES OF ELECTRIC VEHICLES:

Electric vehicles can be classified based on their energy sources, their propolsion devices and how their propulsion devices are hybridized-

  1. Hybrid Electric Vehicle- HEVs are powered by both gasoline and electricity. Vehicle’s braking system generates electric energy to recharge the battery. This is called ‘regenerative braking’, a process where the electric motor helps to slow the vehicle and uses some of the energy normally converted to heat by the brakes.
  2. Plug-in Hybrid Electric Vehicle- PHEVs can recharge the battery through both regenerative braking and plugging into an external power source.
  3. Battery Electric Vehicle- BEVs are fully electric vehicles with rechargeable batteries and no gasoline engine. They store electricity onboard with high-capacity battery packs. Their battery power is used to run the electric motor and all onboard electronics.
BATTERIES IN ELECTRIC VEHICLES

Batteries are an essential part of any electric vehicle. When we talk about any vehicles, the most critical part is power-source which is then responsible for driving any vehicle. In conventional vehicles, this power comes from the engine, which uses the combustion of fuel during this process in the engine the different losses cause the reduction of the efficiency of performance of cars. Here the energy we get from the combustion of fuel. Therefore, the energy storage device is a fuel tank, which has the efficiency of storing energy is nearly 100%, and the engine has the efficiency of nearly 30%. But in the case of electric vehicles, the scenario is much different. The device which runs the electric car is the AC induction motor which has the efficiency nearly 85-97% and energy storing device is electric batteries which have the best efficiency till now is 30%, therefore, increase in performance of electric car batteries can bring a revolutionary change in electric vehicles in society.

LITHIUM ION BATTERIES
The electric car batteries use a chemical cell to store the energy. In EV batteries this cell is Lithium-ion batteries. The lithium is a very reactive metal in the periodic table which has the highest potential of -3.05 V and makes it the best electrode for the batteries. Another electrode for the lithium-ion batteries is graphene. Electrolyte between these electrodes is LiPF6.
Working: The lithium metal is very reactive, but when it bonds with metal oxide, it is stable. When the battery is in charging condition, the higher potential is applied to the graphene electrode, which attracts the loosely bonded lithium-ion from metal oxide electrode. Now the lithium ions pass through the electrolyte and combine with graphene electrodes. The main working of electrolyte is only to allow the metal ion and does not allow electrons to pass through the electrolyte. So, electrons have to pass through the outer circuit of the cell and because of the flow of electrons from the external circuit, it causes the current to flow. These electrons with the help of outer circuits reach the cathode and combine with graphene electrodes. During the discharging condition, the external potential is removed, and the metal oxide attracts the lithium-ion from graphene. The same phenomenon happens again but in reverse form. During the working of the battery, the electrolyte should always be present between the electrodes. If the electrolyte is vaporized, then an explosion will take place in the battery due to short-circuit. Lithium-ion batteries are also temperature sensitive; change in temperature leads to a decrease in performance of the battery. EV has a Battery Management System (BMS) and glycol-based cooling system which prevents overcharging condition and keeps battery temperature within the operating temperature.
ADVANTAGES
  1. High energy density: potential for yet higher capabilities.
  2. Low self discharge.
  3. Low maintenance.
LIMITATIONS
  1. Requires protection circuit to maintain voltage and current within safe limits.
  2. Subject to aging, even if not in use.
  3. Expensive.
  4. Metals and chemicals are changing on a continuing basis
LITHIUM METAL BATTERIES
One of the most crucial materials in current electric vehicles could be getting a significant upgrade. Researchers have developed a coating that could make a long-held idea, the rechargeable lithium metal battery.
Lithium metal is known as the “dream material” for batteries. This is because, among known solid materials, it has the highest energy density. This means that batteries could run twice as long and hold more energy than lithium-ion batteries. While lithium-ion batteries work by passing lithium ions between a graphite anode and a lithium cobalt oxide cathode, the anode in a lithium-metal battery is made of the high-energy lithium metal.
ADVANTAGES
  1. It can hold more power than lithium ion batteries.
  2. Lightweight
  3. Higher energy density
  4. Longer battery life.
LIMITATIONS
  1. Dendrites grows on the lithium metal which causes electric shorts, fires, or explosions.
  2. They lose their ability to charge very rapidly.
SOLID STATE BATTERIES
Solid-state batteries are smaller, faster to charge, less flammable and around 30 per cent more lightweight, therefore offer several advantages over lithium batteries. Also, these batteries have high energy density and contain a solid electrolyte instead of a liquid electrolytic solution. These batteries also enhance the safety of the EVs. Automakers like Bently, Ford, BMW, Hyundai are working on solid-state batteries.
This battery technology uses solid electrodes and solid electrolyte. Materials used in solid electrolytes in solid-state batteries include ceramics, glass, sulfides and solid polymers. The cathodes are lithium-based. One promising cathode material is Li-S, which has a theoretical energy density of 1670 mAh/g.
ADVANTAGES
  1. They have higher energy density
  2. They may avoid the use of dangerous and toxic materials found in commercial batteries.
  3. They are believed to have low risk of catching fire as solid electrolytes are nin flammable.
  4. They are believed to allow for faster charging.
  5. Higher voltage and long cycle life is also possible.
LIMITATIONS
  1. They are traditionally expensive to make.
  2. They might face problems at low temperature and need high pressure to work.

As noticed, most of the problems faced by batteries are at a lower temperature because chemical reactions slow down at low temperature. So for proper charging and discharging of electric batteries temperature has to be maintained. One of the methods to maintain the temperature is by using Compression pads.

COMPRESSION PADS
  1. They are also known as dielectric foam.
  2. They are used to maintain pressure on the face of the pouch cells.
  3. They may also be used to insulate the cells to promote and maintain a uniform face temperature.
  4. Compression pads keep pressure on the battery pack that ensures continuous electrical and thermal connections while allowing enough space in the package itself to expand and change shape.
  5. The spring-like behavior of the foam deflects and returns energy and then diffuses it across a range of compression amounts, a property called compression force deflection (CFD).
  6. Foam cushioning resists permanent deformation when exposed to extreme pressure or compression loads, and will typically maintain effectiveness beyond the lifespan of the battery pack.

Temperature is the most important factor in charging and discharging of the batteries. Methods are concluded for prolonging the Ev batteries life.

  1. Limit ultra-fast charging, especially when the battery is cold. Use Level 2 when possible.
  2. Only charge the battery to the level needed for the daily routine. Full charge hastens capacity fade.
  3. Do not discharge the battery too low as this increases the internal resistance. Charge more often.
  4. Charge and use the battery at room temperature. Operating when cold reduces capacity.
  5. Store the battery in a cool place at partial charge. Usage and storage have different requirements.
  6. Moderate the battery to room temperature in winter before charging and driving. The BMS may do this automatically.
  7. Charge the EV after a sabbatical. Resting at low charge reverses capacity fade.
  8. It is best to let the battery rest at low SoC and only charge before use. Dwelling at low charge reduces calendar aging and may also reverse capacity fade.
ELECTRIC VEHICLES IN INDIA

Pollution in India is one of the major concerns. Of the most polluted cities in the world, 21 out of 30 were in India in 2019. A significant percentage of the pollution is caused by vehicles. Electric vehicles promise zero tailpipe emissions and a reduction in air pollution in cities. Some steps need to be taken to increase the use of electric vehicles in India.

The government took steps-

  1. The Indian government has created momentum through its Faster Adoption and Manufacturing of (Hybrid &) Electric Vehicles schemes that encourage, and in some segments mandates the adoption of electric vehicles (EV), intending to reach 30% EV penetration by 2030.
  2. The scheme creates demand incentives for EV and urges the deployment of charging technologies and stations in urban centres.
  3. Various fiscal demand incentives have been put in place to spur the production and consumption of EVs and charging infrastructure - such as income tax rebates of up to INR150,000 ($2,100) for customers on interest paid on loans to buy EVs.

Steps that can be taken by the government-

  1. The government can collaborate with companies like Ola, Uber, Jugnoo and can ask them to use electric vehicles as their means of transport.
  2. More and more public transports can be converted into electric vehicles like electric buses, autorickshaws, etc.
  3. “Ahmedabad Municipal Corporation will become the first civic body in the country to provide a facility to charge electric vehicles in its multi-level parking lots.” Such types of steps should be done in every city.
Conclusion

In recent years pollution is one of the significant problems that we are facing, and another one is the decrease in the amount of petroleum resources, up to some extent the solution of this problem is the use of electric vehicles. Electric vehicles have many advantages over traditional vehicles, but the problem is the energy storage system which is the battery. Our idea is to optimize the battery performance by changing the electrode used inside a lithium-ion battery which is a silicon-based nanostructured electrode in place of the graphene-based electrode. To increase the use of electric vehicles in India, the government should take some steps like increasing the number of electrically run public transport, by collaborating with companies like Ola, Uber and building more charging stations for the charging of electric vehicles.

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