Your battery is made of three (basic) parts..the anode and the cathode and nonaqeous electrolyte with a Lithium salt. When you charge your battery, you apply a voltage that forces Lithium ions (Li+) to flow out of the cathode and into the anode through the electrolyte. When you discharge the cell, the exact opposite happens. That is all fine and good, except both the anode and cathode are crystalline structures. So although in a perfect cell this diffusion from one xtal structure to another happens nicely and uniformly, in reality it does not.
Imagine an xtal structure where everything is a cube, i.e. you have neat rows and columns of molecules and these are connected via chemical bonds
File:Kubisches Kristallsystem.jpg - Wikipedia, the free encyclopedia
Note that not all xtals are this strucure, but this is the easiest to think about.
Now, to put Lithium in there, you have to have to put it in what are called interstitial spaces...the spaces in the middle of that cube. So that is where the Li+ goes. But the first layer of cubes can only hold so much lithium, and so some Li+ has to go to the interstitial spaces in second layer of cubes, etc. But to get from one interstitial space to another is not a trivial task. It requires that the xtal lattice bend and siform a bit for a tiny amount of time. That is no problem as it snaps right back to normal.
However, if you start forcing Li+ into those spaces at too quick a rate, the xtal lattice will deform so much that the energy for permanent deformation will have been reached, and it will permanently deform. You have now ruined your battery.
Most chargers that push 2A are fine...your phone will limit itself to 1A or so. But some of the chargers push 2A into a battery by upping the voltage (IIRC the iPad charger charges at ~7.2V, i.e. the proper voltage for 2 Li-Ion cells in series). The cheap ones may only go up to 6 or so V, but even that is pushing it a bit.
So...to be safe, DO NOT USE ANYTHING OTHER THAN STANDARD USB SPEC CHARGERS
On a side note, when you do this your electrolyte also has a tendency to degrade (it does taht normally, but much slower). Most batteries are vented to that the gas byproducts of degradation can go out. But if you degrade so quickly that the vent cannot release pressure fast enough, the battery explodes. That is a sight to see, but only if the battery is in a glove box.
PS I am a Chem Eng and Physics student at good engineering school, and I worked in a MatSci lab testing new cathode xtals that had the potential to have anywhere from 4 to 12x more capacity that current xtals used. I used to make Li-Ion batteries by hand, from the synthesizing of the cathode to pressing them into a small metal case.
If you were in the DINC thread, you may remember my battery speaches.
