Mobile devices have transformed our lives, giving us the freedom to talk, work, watch and listen on the move.
But unplugged from the mains, they only last as long as the energy held within their batteries.
While scientists are constantly dreaming up new ways to generate and bottle energy - from rhubarb and paper to viruses and urine - commercial battery technology has changed remarkably little in the past 50 years, particularly when compared with the advances in the devices they power.
As Tim Probert, editor at Energy Storage Publishing, says: "The battery industry is pretty conservative. It says a lot that we are still using very old technology like lead-acid in batteries.
The humble AA battery has been around since the 1940s and is based on 19th Century technology.
Most laptop manufacturers gave up on 18650s long ago, but Tesla believes this old tech still has a future, and even has plans to build its own "gigafactory" to produce them.
"By choosing smaller, cylindrical cells, we have been able to save on manufacturing costs," explains Tesla's Laura Hardy.
"Smaller cells, which can have a better energy density, gave us more flexibility in packaging the cells and creating the battery pack."
By putting 7,000 of these cells together, Tesla's Model S Sedan is able to achieve a range of up to 300 miles, considerably more than many of its competitors using more advanced battery technologies.
Most other manufacturers use pouch cells, which involve lithium cells being placed side by side like slices of bread. The danger here is the risk of "thermal runaway", where one cell short-circuits and produces so much heat it sparks a ripple effect and the battery blows up.
This is thought to be what happened to Boeing's Dreamliner passenger jet in Japan at the beginning of last year.
The next generation of lithium-ion batteries will help solve this problem by replacing flammable liquid electrolyte with safer, solid-state components. This type of battery is also more powerful per unit.
The more realistic and exciting developments are taking place away from pure battery technology.
The first is wireless power - charging your gadgets without having to plug them in to the mains.
He discovered that a small amount of power is transmitted alongside the radio waves, and set about researching how best to focus the signal from many antennae working in unison as a means to charge devices remotely. In 2013, more than decade later, Mr Zeine launched Cota.
"Cota comes in two parts - a charger and a power receiver," Mr Zeine explains. "Think of the charger as similar to a wireless router, and the receiver as a button battery."
"The receiver sends out a low power signal to the charger, which in turn sends back a signal from each of its thousands of antennae, targeted specifically at the receiver itself. The receiver will then track the device constantly."
The benefits are obvious. You no longer have to worry about recharging your phone or laptop, as it will do so automatically whenever it is within range of a charger.
This means the battery doesn't need to store as much energy, and so can be made much smaller - the holy grail for all consumer electronics manufacturers.
from the BBC