We are living in an era where people want every work to be done using mobile phone itself. As this demand increased, demand to have more storage space and long lasting battery power also increased. This led to the advancement in mobile technology. Since, phones are getting sleeker day by day, batteries also needed to be lighter and smaller in size. Technologies used in batteries of old mobile phones are not environment friendly, so batteries with less toxic substances have become necessity. Lithium-ion batteries are one among them and widely used nowadays. Even though it is environment friendly, lighter and holds more energy, recently it started seeing breakdown because of its unexpected explosion.
Lithium-ion batteries contain two electrodes on opposite sides. One electrode known as cathode holds positively charged ions and filled with lithium. Other electrode is called as anode and holds negatively charge ions. These electrodes are submerged in a liquid or paste called an electrolyte. When a phone is being charged, positively charged ions flow from cathode to anode. When a battery is being used, the ions flow the other way. During this flow, it is highly recommended that the anode and cathode should never touch to prevent redirection of energy to electrolytes. Manufacturers insert separators in between to avoid this collision. But because of flaws in separators, electrodes come into contact and results in fire. This is said to be the reason for Samsung Galaxy Note 7 explosion.
Overcharging or quick charging also leads to battery failures. Dan Steingart, a materials scientist at Princeton University says battery is like a rubber band. Stretching a rubber band is similar to charging your phone whereas releasing a rubber band is similar to using your phone. If a rubber band is being stretched too much, there is a chance of it breaking. In the same way, if too much of lithium goes to anode, there is a chance of explosion. Since, we want battery to be charged quickly, we go for the chargers of higher volts though it is not compatible with the battery. This might lead to battery failure. So it is preferred to use chargers of same manufacturers as of battery makers. Steingart also explains the problem of quick charging by referring batteries to two egg crates. For a battery to function properly, lithium ions need to flow slowly between the spaces of two egg crates. If lithium ions move too quickly, then it will deposit itself on the outside of the egg crate and then onto itself. This results in battery short out if lithium ions move faster every time while charging.
To overcome the above problems, advanced battery chemistries such as lithium-sulphur and lithium-silicon are being worked on. Scientists are also developing an electrolyte by name “ionic liquids” which won’t explode easily. A company by name “Sakti3” came up with solid-state battery where the liquid electrolyte in the battery is replaced by a solid substance. Company says it can store over 1,000 watt hours per litre, which is almost double of the traditional lithium-ion batteries available today with an energy density of up to 620 watts per hour per litre. This batteries are said to be cheaper, long lasting and more environment friendly than lithium-ion batteries. Solid-state batteries also overcome safety issues around the explosive nature of liquid batteries. Even though new technologies are evolving, lithium ion batteries are widely used nowadays and its upto us to follow some precautions while charging our phones until new technologies are accepted by current market.