Here's how the experiement was set up, as explained by Palmer:
Using an alternating current, driven by a transformer, over 200,000 volts was sent across a 300mm gap – giving heat and light similar to that of a lightning bolt. The signal was then stepped into a second controlling transformer, allowing us to charge the phone.
We were amazed to see that the Nokia circuitry somehow stabilized the noisy signal, allowing the battery to [start] be charged in only seconds.
Nokia have partnered with the University of Southampton to unveil ground-breaking, proof-of-concept research into harnessing the power of lightning for personal use, an industry first that could potentially see consumers tap one of nature's significant energy sources to charge their devices in a sustainable manner.
This experiment underlines Nokia's 150-year commitment to innovation and delivering the most pioneering products to its customers. That the Nokia Lumia 925 could withstand this sort of experiment is testament to the renowned high quality and durability of Nokia's devices and the company's continuing research to increase the already outstanding reliability of its products.
These experiments are conducted by professionals in laboratory conditions, please do not try this at home.
More information in this Nokia Conversations story.