Overview & Challenges
Before we dive into Solid State Battery, it is important to understand how the Li-ion battery works. Ever wondered why Li-ion batteries are so popular? Did it ever occur to you that why do all the phones have Li-ion batteries? Did you understand the science behind energy density and energy capacity? After reading this article, hopefully all your questions can be answered. To know more, keep following our blog TheCarsInsider.
Recent research done from Samsung found that changing Anode material in Li-ion battery to Silver-Carbon (Ag-C) composite layer may change how we utilize batteries to store energy and can certainly change the way we use battery pack in electric vehicles. Research team at Samsung Japan (Hyper link) claims to increase energy density up to 900Wh/L meanwhile also reducing volume of battery pouch by 50% in size.
How Li-ion battery work – Solid State Battery
Let’s dive into Li-ion battery cell. It is important to understand that battery pack and battery cell aren’t the same. Battery pack can only be formed when number of battery cells are connected in parallel and series or in some other combination.
All battery cells have different materials to act as electrode and some other material to act as electrolyte. There are number of different cells, such as Nickle-Cadmium (Ni-Cd), Nickle-Metal Hydride (Ni-MH), Lithium Ion (Li-ion) and Lead Acid etc.
Some cells are called as primary cells, and some are called as secondary cells. Primary cells are considered as non-rechargeable cells and secondary cells are considered to be rechargeable cells meaning once it is fully discharged then we can charge it back again to its original state.
Electrode and Electrolyte in Lithium-Ion
Li-ion battery cell have electrode to be working as Lithium electrode and electrolyte as Lithium salt. Positive and negative electrode work to exchange the electron through outside circuit and to trade lithium ions through electrolyte. When discharging cell, anode (Negative electrode) let out electrons through external circuit and it lets Lithium ion flow through electrolyte to positive electrode. There is also a separator usually made of ceramic to work as separator for electrodes. Negative electrode is usually made of Grephene which is part of Graphite and over the time it gets used up and cell gets completely discharged.
Important to note is that, Anode is like sponge which can have Lithium atoms in its crystal structure just how sponge can have water when soaked and can be returned to original state meaning Lithium atoms have traveled from Anode to Cathode and cell is discharged. When charging a cell, Lithium ion again flows from positive electrode to negative electrode through electrolyte and electron flows from external circuit bringing back the cell to its original state of charge. When number of cells are connected in series or parallel or in some other combination then it is called battery pack. By doing this, we can achieve higher output voltage and higher battery capacity.
It is of paramount important that we understand the basic battery terminology such as voltage, capacity, energy density and specific energy.
Voltage: It is defined as electromotive force or potential difference expressed in volts. When taking voltage in battery terminology, we often consider the voltage to be nominal voltage. Nominal voltage is the voltage as which battery cell is designed to operate at and can be found on battery specification. OCV (Open circuit voltage) is the voltage when battery cell isn’t connected to any external load and we are neglecting harsh resistance. OCV is used in mathematical models to determine the SOC (State of Charge) calculation. There are numerous amount of research done in this area to properly estimate the SOC and to optimize the battery pack.
Capacity: It is the measure of the charge stored inside the battery. Norm is to measure the capacity in Amp-hour (Ah) or mAh. This can be found in battery specification. Higher the capacity, higher the load we can run through the battery. Depending on the voltage, we can determine how long we can have that same amount of load connected till we can completely drain our battery cell.
Energy density: It can be defined as the amount of energy that is stored in cell per unit volume. It is easy to understand that high energy density is always desirable.
There are numerous advantages of using Li-ion batteries. However, we will just outline them on surface instead of going so much in details as it could be another whole article.
- Higher energy density
- Relatively lighter compare to other battery cells
- Higher specific energy
- Slow ageing against time
- Lower energy loss in thermal heat generation
Getting more into Solid State battery and what it is that causes everyone’s attention as it is going to drive the future of electric world. Solid State batteries have higher energy density and it is because they are not using the liquid electrolyte and instead uses the solid electrolyte which in turn is very useful.
Advantages of Solid State battery.
It is believed to have higher energy density. In the manufacturing process too, we can avoid the harmful or toxic materials that can be found in other commercial battery and that way solid-state are more environment friendly. Most liquid electrolyte are flammable, however, solid electrolyte are believed to have lower risk of catching a fire with few of the safety putting in places. They are also believed to allow for fast charging and high voltage and life cycle.
Few of the challenges with Solid-state batteries are,
- Formation of Lithium dendrites. These dendrites causes to penetrate separator in between anode and cathode because of which there are higher chances of short circuit.
- Associated cost with making solid-state batteries. Main cost lies with manufacturing process and the difficulty to scale the production to higher numbers.
- Temperature and pressure sensitivity are also critical for Solid-state batteries.
Seeing how the world is advancing through the leap and bound research in Electric areas and battery capacity, it is not far that we can see those applications where you can drive your Electric Vehicle (EV) about 5000 km just based on one single charge. However, before reaching to that, we have lot of challenges ahead and we will overcome them as companies like Samsung, Panasonic and Tesla keeps competing.
To read more about whether to buy Electric or Gas car in 2020, head over to our popular posts.