Sorry for my late reply Nic, but do you mean a something third party like an Energiser Power Bank, or a Sony dummy battery with a USB? It's the power bank option I was looking for.
Features: USB port, plug and play, very convenient. You need a 5V 2A power bank, mobile power supply or charging connector (not included) to power the power, greatly extend the recording time of your camera. Suitable for Sony ILDC cameras such as Sony NEX-3/5/6/7, A33, A37, A35, A55, a7, a7R, a7I...