Nearly every smartphone and laptop today is powered by a lithium-ion battery. These batteries are desirable for their small size and large capacity. Nobody wants to carry around a phone that only lasts a few hours on a charge, or that hardly fits in a pocket due to a large battery. The trade-off is that lithium-ion batteries have relatively poor durability. Your phone will hold less of a charge in a year than it does now – or perhaps not charge at all. The causes of this range from overheating to unavoidable imperfections in the chemical reactions powering the batteries that run our devices.
Imperfect Chemical Reactions
Lithium-ion batteries work by moving lithium ions from the negative electrode of the battery to the positive electrode, releasing energy in the process. Charging performs the opposite reaction, moving ions from positive to negative. All batteries operate using chemical reactions similar to this, although lithium-ion batteries are best suited for use in portable consumer electronics.
One reason batteries die is due to these underlying chemical reactions. Lithium ions will occasionally bond with the negative electrode in an irreversible way. This reduces the number of lithium ions available for future discharges, permanently decreasing the battery’s capacity. This process begins as soon as the battery is created at the factory and continues until the battery is completely dead. Additionally, this is the very reason why alkaline batteries have an expiration date.
Overheating
Batteries also begin to fail due to heat. Charging and discharging batteries produces heat, which increases the speed at which these batteries fail. Proper ventilation can resolve this; for example, charging your laptop on a hard surface rather than a soft blanket or cushion will help to improve its battery’s lifespan. Keeping your phone out of the sun during the summer can also help with this, especially during heavy use or while charging.
Constant Charging
Laptops, in particular, suffer from another cause of battery failure: constant charging. Leaving your laptop plugged in constantly does help to keep it charged, but this also reduces how much charge it can keep. Unplugging and re-plugging your laptop throughout the day or keeping it unplugged (and turned off) when unused will greatly improve battery lifespan. Smartphones are relatively safe from this cause of failure, as they are usually kept in a pocket for most of the day rather than on a charger.
Long-Term Storage
Batteries can also be killed when left uncharged for long periods of time. Leaving your phone with a dead battery for a few hours won’t affect its lifespan much, but storing it for weeks at 0% may lead to it being incapable of recharging. At the same time, storing a battery with a full charge can also degrade it. Optimally, batteries should be charged up to half of their capacities before being stored for long periods of time.