I second the positive comments from those before me on:
- RAM single sucker (would have never thought how well it works)
- Anker 20100 mAh
- SkyDemon
- RunwayHD
For portable (non-certified) traffic awareness the combination of PilotAware receiver (for peer-to-peer ADS-B In, TPX C/S, Flarm and its own PAW), filtered for relevance by and displayed in SkyDemon (including verbal traffic and airspace alerts) is the best. This should work anywhere in the world.
Please note that while a TCAS screen can run as a sub-window in the nav software on your tablet, you'd really want to try running the traffic alerts on a separate tablet in line of sight (could be a mini tablet).
And reserving your main tablet computer for GPS moving map/route planning, etc. As the latter requires frequent touch input (panning, zooming, look-up, etc.) you may want to strap it to your leg. MyClip is the lightest, and least bulky 'knee strap' that I would use for that purpose.