Batteries underpin much of the advances of the 21’st century. Can you imagine a world without your smartphone or one where you had to plug into the grid to recharge your electronics?
The Lithium-Ion battery today is among the world's most sought-after resources, to the extent that an entire country’s regime has been propped up on the selling of this strategic resource. But the extraction of Lithium and other heavy metals are major sources of environmental pollution in their source countries.
Furthermore, Lithium-ion cells have a finite capacity of around 300-500 cycles, where one cycle is one complete charge and discharge, which can last anywhere from 3-to-5 years
All the major battery manufacturers, like LG, Samsung, and Panasonic, are expected to spend upwards of US$ 150.6 Billion by 2025 on finding alternatives to the Lithium-Ion battery. Alongside them, researchers from the University of Maryland, University of Berkeley, and Tsinghua University are conducting research to push the envelope of battery technology to a much brighter future.
Picture this, you are in your brand new swanky EV and cruising down the highway when suddenly, you get an alert saying that your battery capacity is rapidly reaching zero. You search for a plug-in charging station and thankfully, you find one just within the acceptable range of the remaining battery charge. Reaching there you find that there is a long line in front of the charging station and will take an average of 2-hours to charge your battery.
Charging an EV takes a long time, a really long time. The only models to buck this trend are the EVs released by Tesla, and only if the cars are connected to the Tesla superchargers.
For the EV market to expand rapidly, the time taken to charge batteries will be a huge deterrent. But what if you could remove your dead battery and swap it with a fully charged one?
This is the technology that the Government of India has proposed in its annual budget for 2021-22. Battery swapping. A technology in which users can exchange the expended batteries from their vehicles with new fully charged batteries. This technology significantly reduces the charging time while also decreasing the load on the electric grid. Currently, the technology only supports integration in two-wheelers and three-wheelers.
While Niti Aayog, the think tank of India, has not released any concrete numbers regarding the expected subsidies and investments in the technology, one can make an educated guess based on the global trends.
The global battery swapping market is projected to rise to US$ 850 million by 2030 rising by an estimated CAGR of 24.5% during 2021-2030 of which, India, China, and SEA countries will be a big part.
One of the success stories in the battery swapping space that can be emulated across India is that of Gogoro. A Taiwanese company that is changing the way EVs are viewed across SEA and have to date swapped over 300-million batteries.
Every single Electric Vehicle on the road requires a source of energy and typically, in the case of an all-electric vehicle, a Lithium-Ion battery pack provides this energy. Rechargeable batteries in use around the world have similar physical structures and share a few similarities viz are,
Batteries are generally considered to be lightweight and durable. But, powering an Electric Vehicle requires enormous wattage, and this increase in capacity comes with an increase in the weight of the battery. The lion’s share of the weight of the battery comes from the electrolyte and swapping out the electrolyte will reduce the overall weight of the battery.
Solid-state batteries replace the liquid electrolyte with a solid like glass or ceramic significantly reducing the weight of the battery pack. Solid-state batteries are also much smaller in size, this allows battery manufacturers to stack more cells per meter. A property that when combined with the higher energy density of solid-state electrolytes increases the capacity of the battery. Liquid electrolytes are prone to a phenomenon known as vaporization at high temperatures, where the liquid turns to gas, resulting in the combustion of the battery pack. Solid-state batteries are much safer to operate at higher temperatures and can handle larger loads.
This US$6 Billion solid-state battery market is primed to take over the world by 2030. Driven primarily by the Electric Vehicle boom, the solid-state battery is soon coming to a battery pack near you.
The cathode in Lithium-Ion batteries is composed of metal oxides from Lithium, Nickel, Manganese, and Cobalt. Among the three metal oxides, Cobalt accounts for up to 20% of the total weight of the cathode. However, it is mined from the Democratic Republic of Congo, a country that allegedly uses practices that are not socially responsible. As EV production increases around the world, the global supply chain of Cobalt has been severely hit.
Over the decade, significant progress has been made to reduce the dependence on a metal that is prone to supply shocks. Among all the technologies that are being currently studied, the Sulfur-Lithium battery is the one that is leading the race to replace Lithium-ion batteries as the source of energy storage in the future.
In the Lithium-Sulfur battery, the anode is replaced with metallic Lithium while Sulfur serves as the cathode. Discharging the battery produces Lithium-ions that move through the electrolyte. These ions interact with sulfur at the cathode end converting the sulfur into Lithium Polysulphides. This process is reversed while charging.
The primary reason why Lithium-Sulfur is one of the battery trends to expect in the future is due to its high specific energy, in the order of 450W/kg. The higher energy density of Lithium-Sulfur renders itself viable to be used in electricity storage from renewable sources.
But, Sulfur has low conductivity and requires additional carbon to help create polysulphides during the discharging phases. Repeated creation of polysulphides in the cathode end leads to an eventual decrease in the concentration of sulfur and the number of recharges.
The BMS monitors the Soh (State of Health), SoC (State of Charge), voltage, current, and temperature of the battery. It plays a vital role during the charging and discharging phase of the battery by maintaining a stable temperature. During cases where the temperature of the battery increases, the BMS regulates the heat by controlling the flow of coolants in the system.
But, the BMS only has one to four sensors connected to the battery at any given time. Reducing the data points that can be collected from the battery. When the battery is stressed from more than one anomaly, this can serve as a vulnerability leading to system collapse.
Cloud-based technologies have started to permeate most aspects of everyday life through IoTs. Leveraging the computing power of cloud-based technologies allows for an exponential increase in the processing capabilities of battery management systems. Cloud-based BMS will be able to draw inferences from BMS data obtained from other vehicles in the network. Using a high-fidelity mathematical model of the battery pack, cloud-based BMS will be able to figure out places where the battery temperatures are higher than normal.
Charging or discharging a battery pack generates heat. This heat has to be dissipated from the system. Failure to reduce the temperature of the battery can lead to adverse consequences like the battery exploding.
The most common method of cooling is air cooling. Where fresh air is allowed to move through the component reducing its temperature. This is because air has a low heat capacity and is a good conductor of heat.
Liquid or water cooling is the preferred method of cooling currently used in EVs. In this process, water/glycol solution is forced through a heat pipe that is in contact with the battery. The heat pipe is connected to a radiator which exchanges the heat with the atmosphere through convection.
A fine balance exists between heat that is absorbed and dissipated from the liquid. Battery explosions usually occur when the liquid solution reaches a saturation point.
Immersion cooling is a method in which the entire battery pack is immersed in a heat transfer fluid. The battery pack is connected through a heat pipe to a radiator where heat transfer occurs. Direct contact with the battery pack allows for better cooling solutions. Immersion cooling solution reduces temperature by an additional 9.3% in comparison to liquid cooling.
Research in Electric Vehicles is an ever-evolving field. It was only a few decades ago that Electric Vehicles were considered a pipe-dream. Even with the launch of the Tesla Roadster, it took years of research and development to reach the current state of Electric Vehicles today. A few years ago, battery-powered vehicles were relatively new. Batteries were smaller and the range was shorter. Batteries were only used in hybrid vehicles to power the vehicle during idle and low-speed travel. However, today we have battery-powered vehicles that can reach ludicrous speeds.
This is only possible because of the hard work and dedication of researchers who continue to push the boundaries of battery technology. A career in the battery industry is rewarding and will place the engineer at the forefront of cutting-edge research. Skill-Lync’s program in Electric Vehicles, including our program in battery technology, will help reduce the time taken to reach your career goals. Working on simulations of the battery technologies mentioned above helps prepare the engineer for the varied/evolving expectations in research and development.
In this course, you will get a complete overview of electrochemistry, Battery terminologies, Mathematical modelling, Battery management system, Charging and discharging for EV application and thermal management.
A comprehensive course on Battery Design using practical examples. This course is highly suited for beginners
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