Week 6 Session 13

Q)Discuss two new trends in battery system field.

Solution:

A battery is a pack of one or more cells, each of which has a positive electrode (the cathode), a negative electrode (the anode), a separator and an electrolyte. Using different chemicals and materials for these affects the properties of the battery – how much energy it can store and output, how much power it can provide or the number of times it can be discharged and recharged (also called cycling capacity).

Battery companies are constantly experimenting to find chemistries that are cheaper, denser, lighter and more powerful. Some of the upcoming battery technologies are given below

• Lithium Sulfur Batteries-

In li-ion batteries, the lithium ions are stored in active materials acting as stable host structures during charge and discharge. In lithium-sulfur (Li-S) batteries, there are no host structures. While discharging, the lithium anode is consumed and sulfur transformed into a variety of chemical compounds; during charging, the reverse process takes place.

A Li-S battery uses very light active materials: sulfur in the positive electrode and metallic lithium as the negative electrode. This is why its theoretical energy density is extraordinarily high: four times greater than that of lithium-ion.

• Solid state batteries

In modern li-ion batteries, ions move from one electrode to another across the liquid electrolyte (also called ionic conductivity). In all-solid state batteries, the liquid electrolyte is replaced by a solid compound which nevertheless allows lithium ions to migrate within it.

The first huge advantage is a marked improvement in safety at cell and battery levels: solid electrolytes are non-flammable when heated, unlike their liquid counterparts. Second, it permits the use of innovative, high-voltage high-capacity materials, enabling denser, lighter batteries with better shelf-life as a result of reduced self-discharge. Moreover, at system level, it will bring additional advantages such as simplified mechanics as well as thermal and safety management.