Charging a cell phone battery from a KidWind Turbine may be feasible but is not practical due to the low power output levels. nI checking with our engineering department, they too know of no useful options for this combination of systems. Vernier has no such product and no plans to make one. The 12V KidWind solar cell would make an easier and steadier source for this sort of experiment.
In general, engineering advised extreme caution when using such an unregulated source to charge a battery. The Li batteries are extremely intolerant of fluctuations in the charging system and can catch fire if mistreated. If you are wanting to do field or renewable charging from a low power fluctuating source, you should start by researching using Ni-Cad batteries or open cell lead acid batteries as they do a better job with poorly regulated sources.