Researchers have made a couple of new discoveries that could have an impact on how batteries are charged. The first comes from a team at the Georgia Institute of Technology, which has developed a battery with a charging element built right in. Batteries are typically charged with external devices, but this one integrates a piezoelectric material that gets the electrons flowing when the battery is subjected to physical pressure. The proof-of-concept uses a coin-sized battery attached to the bottom of a shoe, and it's proven to be more efficient than traditional charging methods, albeit at relatively low voltages. Physorg has the details on the new development, which has been described in a paper published by Nano Letters.
Charging a battery with mechanical force doesn't appear to be particularly quick. However, researchers at the Uslan National Institute of Science and Technology in South Korea have figured out how to speed up battery charging by up to two orders of magnitude. Their approach involves soaking the battery cathode in a graphite solution. The cathode is then carbonized to create conductive traces that more quickly distribute life-giving electrons to the cell. According to ExtremeTech, this process speeds the recharging time by a factor of 30-120X. There is a catch, though. The graphite adds to the total volume of the battery, decreasing its effective energy density. More information can be found in this paper published by Angewandte Chemie.
In certain devices, I could see giving up some battery capacity for a solution that charged substantially more quickly. A self-charging battery capable of generating physical force into electron flow sounds even more appealing, though.