You may have difficulty charging Lithion Ion simply because most of the hand held solar chargers don't deliver enough amperage. Something a little more substantial is required. USB is designed to deliver 2.5 Watts i.e. 5V @ 500mA DC, so devices that can be charged via USB can in theory be charged using a solar panel which can deliever more than 2.5W, but when taking into account DC-DC convertion losses and solar variability then a 5-6 Watt panel would really be a minimum.

A 12 Watt panel should handle any USB device which can be charged via USB.


Brunton CIGS folding 12 Watt panel

http://www.amazon.com/gp/product/B0019OO...;pf_rd_i=507846


Brunton CIGS folding 26 Watt panel (weighs in around 740 grams)

http://www.amazon.com/gp/product/B000GEF...;pf_rd_i=507846

Powertraveller SG-010 Solargorilla Portable Solar Charger 10W solar Panel (weighs in around 650grams without its neoprene protective cover)

http://www.amazon.com/Powertraveller-SG-010-Solargorilla-Portable-Notebook/dp/B001L0POUO

These panels can all be connected to a minigorilla Lithium Battery which can deliver over 30W from a 265 gram battery

https://powertraveller.com/iwantsome/primatepower/minigorilla/

With the Brunton panels you would just need a 12V cigar/single or twin USB adapter for single or twin USB devices with the Solaris 12V panel.