What are electric car batteries made of?

Polo Lu
on
April 2, 2024

Look around the streets near you. You will find EVs all around. They are not a niche now and slowly moving towards their path of becoming majority in the overall automobile market. But at the heart of every EV is…

Look around the streets near you. You will find EVs all around. They are not a niche now and slowly moving towards their path of becoming majority in the overall automobile market. But at the heart of every EV is its battery. It is a known fact that batteries are one of the most important components of an EV. The EV battery is combination of different materials that stores and manages the electrical power of your EV.

Now let’s discuss in detail about EV battery – what it is, what it is made of, what are its parts, types of EV batteries and more.

Before we go further into EV batteries, we need to know about electric batteries in general.

Battery is device which stores electrical power in it in form of chemical energy. Battery outputs electric power by converting chemical energy into electrical energy. It stores power by converting electrical energy into chemical energy.

An EV battery is the battery specifically used in electric vehicles.

When you talk about EV battery components, there are different versions of EV battery based on physical structure and chemical composition.

An EV battery is made of numerous individual units called cells. These cells are grouped together into modules which then form a battery.

Now there are 3 main types of cells used in an EV battery- cylindrical cells, prismatic cells, and pouch cells.

  • Cylindrical cells – these are the most common types of cells found in EV batteries. Cylindrical cells look similar to common AA/AAA batteries you use at home. Now, the size of these cells can vary but overall shape remains the same.
  • Prismatic cells – these are rectangularly shaped cells and can be up to 20 to 100 times larger. They use less material for the casing, therefore can store more energy and deliver higher power, while also managing heat better than cylindrical cells. While less popular than cylindrical cells, their use has been steadily growing and they may replace cylindrical cells in many areas in coming future.
  • Pouch cells – these cells are encased in a soft plastic casing, making them very efficient in terms of space usage. That said, their fragile casing means they usually require additional protection to prevent mechanical damage to the cells.

Now, if we go further. The type of batteries also varies according to the chemical composition of the cells.

To understand this, we need to know what is inside a cell.

An electric cell of a battery operates on the fundamental principle of electrochemistry. This means chemical energy is converted to electrical energy. This output electric energy is what powers the motors of your EV.

Internal diagram of cell

The main components inside cell of a battery are –

  • Electrodes – electrical conductor
    • Negatively charged electrode (anode)
    • positive charged electrode (cathode)
  • Electrolyte – a liquid or gel like electrically conducting medium inside cell
  • Separator – permeable membrane placed in between a battery’s anode and cathode to prevent their direct connection

The whole process involves the flow of electrons from a negatively charged electrode (anode) to a positively charged electrode (cathode) through an external circuit, powering the vehicle’s motor. The electrically conducting medium through which electrons move inside the cell is called the electrolyte.

The performance of an EV battery depends on these key components: the anode and cathode materials largely determine the battery’s capacity and power output. While the electrolyte’s composition affects the battery’s efficiency. Separators play a critical role in ensuring safety by preventing short circuits.

Now, the type of material used for electrodes and electrolyte defines the performance of the cell – output power, size, efficiency and life span.

Lithium-Ion Batteries

Lithium-ion are currently the most preferred option for batteries due to their high energy density and small size.

In lithium batteries – the cathode is made up of Lithium based compounds while anode is made up of carbon (graphite) as the anode. They are immersed in a lithium salt electrolyte solution.

While, Lithium is still the dominant battery type – there is continuous research and development on going to further reduce its cost while improving its safety, longevity and capacity.

Nickel-Metal Hydride Batteries

Nickel-Metal Hydride (NiMH) is made up of a nickel-based cathode and a metal hydride anode. The electrolyte is usually potassium hydroxide

Nickel- Metal based batteries were once most popularly choice for use in Electric Vehicles especially hybrid vehicles. But more and more manufactures are now starting to adopt Lithium batteries.

Nickel-metal hydride (NiMH) batteries offer a reliable, albeit heavier, alternative to lithium-ion systems.

Despite being overshadowed by lithium-ion batteries, they still remain strong option for certain applications due to their robustness and less critical raw material requirements like power backups in challenging areas.

Solid-State Batteries

Solid-state batteries are the latest innovation in the world of EV battery technology. A solid-state battery uses solid electrodes and a solid electrolyte, instead of the liquid or polymer gel electrolytes found in lithium or Nickel type batteries. This makes the battery fully solid without any liquid or gel component, that is why they are called Solid-State batteries

Solid state batteries promise a higher energy density, improved safety, and longer life span. Solid-state technology is still in developmental stages but holds the potential to drastically change the EV landscape with its advantages.

Table comparing key aspects of lithium-ion, nickel-metal hydride (NiMH), and solid-state batteries:

FeatureLithium-ion BatteriesNickel-Metal Hydride BatteriesSolid-State Batteries
Energy DensityHighModerateVery High
SafetyModerateHighVery High
ReliabilityHighHighExpected to be High
Form FactorSmall and FlexibleBulky and less flexibleHighly Flexible
CostModerate to HighLow to ModerateCurrently High

EV battery is a combination of a lot more hardware and software components other than raw materials that make up its cells. Let’s have a look at an EV battery’s main features. 

Battery Module Array

The battery module array is the power storage unit of the battery. They are made up of cells as we have discussed above. These cells are grouped into modules, each containing a specific number of cells wired together. These modules are then connected to form the final, full-sized battery pack or more commonly defined as an EV battery.  

Battery Management System

The Battery management system is the brain of an EV battery. The BMS controls every aspect of the battery and ensures it performs optimally. The tasks of BMS involves monitoring and regulating each cell’s charge level, deciding which cells to charge or discharge. BMS also keeps the overall track of the battery’s temperature.

If any part of the battery’s operation experiences any issue, the BMS tries to automatically adjust energy use to protect the battery pack and, if needed, alert the driver.

Battery Electrical System

The battery electrical system refers to all the wiring, connections, fuses, and other electrical components that are part of an EV battery. It is designed to withstand high voltages and is part of battery management system to efficiently manage each cell.

Battery Cooling System

Similar to how the batteries of your phone or laptop get hot during prolonged use, EV batteries also get hot. Due the of the size and scale of EV batteries, they can produce a lot of heat which can lead to fire hazards. This generated heat needs to be dissipated – here is when role of the battery cooling system comes. Typically, this cooling consists of a sealed coolant that can carry the heat away from battery cells and dissipate it in the air.

Battery Protection Casing

The EV battery needs to be protected from external factors like wind, heat, water etc, while also firmly holding all the components together. This is the role of the battery protection case. It is designed to ensure that battery is airtight, waterproof, flame-retardant, and resistant to various shocks and vibrations.

Manufacturing Processes

The manufacturing of an EV battery is a complex process involving multiple precise steps like assembling the anode, cathode, electrolyte, and separator into a functional unit. The process also needs to ensure the batteries’ performance, safety, and reliability

Here’s a general overview of the process:

1. Design and Development

This initial phase involves defining the battery’s specifications, such as chemistry, capacity, and size, according to the EV’s requirements.

2. Raw Material Procurement and Preparation

As we now know Car batteries are made up of raw material like lithium, cobalt, nickel, and graphite. These elements are not easily available. They are sourced globally and processed to meet high-quality standards essential for battery production.

3. Electrode Manufacturing

The anode (typically graphite) and cathode (lithium metal oxide) materials are processed, mixed with a binder (in simple terms a glue), coated onto current collectors, then dried and compressed, forming the battery’s energy-storing components.

4. Cell Assembly

After electrodes (anode and cathode) are made, they are assembled in a way that they are separated by a porous separator in an electrolyte solution and then sealed in a casing. This sealed casing forms a cell.

5. Module and Pack Assembly

Cells are then grouped into modules and assembled into a final battery pack. Next, they are integrated with a battery management system (BMS) and cooling systems to oversee performance and safety.

6. Testing and Quality Control

To ensure safety, longevity and performance. Each battery pack undergoes extensive testing for charge/discharge cycles, temperature tolerance, and durability, ensuring it meets rigorous standards.

Recycling and Sustainability

Till now we have been discussing about types and manufacturing the car batteries. While the EV vehicles have been great help in reducing the environmental impact from fossil fuel driven IC vehicles.

The raw material used to make EV batteries also have an environmental impact. That is why the recycling and sustainable adoption of EV batteries becomes crucial. Governments and vehicle manufacturers are all greatly focused on this aspect.

There is constant ongoing research on innovative way to recycle the batteries. Recycling programs aim to recover valuable materials like lithium, cobalt, and nickel, reducing the need for new raw materials and minimizing environmental impact. Efforts are also underway to improve the recyclability of batteries and develop batteries with less harmful and more abundant materials.

Governments all around are looking to implement policies and industry standards that promote sustainable practices within the electric car battery sector, including monetary incentives for recycling and the adoption of greener manufacturing technologies.

Future Trends in Electric Car Batteries

There are constant Innovations that are being explores in battery technology. Continuing to push the boundaries of material science, with overall focus on increasing energy density, reducing costs, and enhancing safety.

Upcoming and future trends include the development of lithium-sulfur batteries, Sodium -Ion batteries, advanced solid-state batteries, and more exploration of battery materials that are more abundant and environmentally friendly.

Outro

As electric vehicles become increasingly inseparable part of global transportation. The batteries and its material that make it are also gaining more prominence. The ongoing Research and development in the areas of battery technology promises not only improved performance and affordability for EVs but also a significant step forward in achieving a sustainable future.

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Polo Lu

General Manager Jiangsu Lutong Electric Co.,Ltd