Lithium-ion batteries are made up of safety measures to avoid any unwanted conditions occurring where batteries are being used. Some of them are as follows: Pressure-sensitive vent holes Because batteries are pressured, they require a metal outside wall with a pressure-sensitive vent hole. This vent will let out excess pressure if the battery is at risk of overheating and bursting due to overpressure (pressure buildup at 3,000 kPa), which will stop other cells in the battery pack from catching fire. Temperature Coefficient that is positive (PTC) This switch guards the battery against current spikes to stop it from overheating. Like other chemistries, lithium-ion cells discharge themselves. Self-discharge is the loss of a battery's stored charge without the electrodes or an external circuit being connected. Chemical processes inside the cell cause this to happen. Cell self-discharge rises with age, cycling, and high temperatures. Temperatures may increase as a result of elevated sel