Mophie has announced the Space Pack, a battery case for the Apple iPhone 5 and iPhone 5s that adds not just extra battery power but storage too. The case was shown off first at this year's CES show in Las Vegas. More CES news here.

The Mophie Space Pack (from £139 or US$150) is the world's first iPhone case with built-in storage. It not only doubles the battery of the iPhone, but increases its storage capacity, allowing users to keep more apps, videos, music and photos than their iPhone would normally allow.

Mophie Space Pack UK release date and price

Available in 16GB (£139) and 32GB (£169) models the Mophie Space Pack is a low-profile case that resembles the company's popular Juice Pack battery cases for iPhone. See Mophie Juice Pack battery case reviews for iPhone 5 and 5s.

The cases should be available in the UK and Europe in "spring 2014" says Mophie. It will be available in both silver/grey and matt black cases.

Any file type can be stored and managed on the Space Pack.

Users can backup all photos and videos in the iPhone Camera Roll to the Space Pack, freeing up space on the iPhone 5/5s for apps and other files.

Music and movies can also be stored and played on the Space Pack via the Space app.

AirPlay integration allows users to easily send documents, photos and movies to a TV, monitor, or speaker with a compatible Airplay Device.

In addition AirDrop integration allows users to easily send files to other iOS devices.

New Mophie Space app manages storage on iPhone

The battery/storage case uses Mophie's free iOS app Space, with which users access and manage content within the Space Pack without requiring network or WiFi access.

Space automatically organises all of the files on your space pack into Collections, which sort by file type regardless of folder structure giving the user an intuitive way to interact with each file type.

The Mophie Space Pack allows the user to charge and sync their iPhone from their computer.

The Mophie Space Pack is available now for pre-order for $149.95 (16GB) and $179.95 (32BG), and ships on March 14, 2014. UK pricing has not yet been announced, but we would expect pricing to be around £139 for the 16GB Space pack and £169 for the top-of-the-range 32GB Mophie Space Pack.

"With an iPhone case that provides the charging solution and low-profile protective design expected from Mophie, we've taken the next step and developed an entirely new category, pushing the increasing trend toward mobile computing even further," said Mophie CEO and co-founder Daniel Huang.

Now read: Choosing the best battery case for the iPhone 5 and iPhone 5s.