Depending on chemistry and construction, Lithium chargers provide 4.1 or 4.2 volts per cell. The following is from a Poly Quest data sheet:
"PolyQuest engineers designed the Protection Circuit Module (PCM) to greatly reduce the chance of accidents while charging lithium polymer batteries. It is critical that each cell is
limited to a maximum charge voltage of 4.2 volts per cell and that only chargers approved for lithium polymer batteries are used."

There are no chargers that charge individual cells, except single cell chargers (that is a pack with only 1 series cell in it). Things like the Poly Quest PCM Guard monitor each cell's voltage to protect against exceeding the 4.2V per cell limit. If the PCM Guard detects a cell inbalance, it disconnects the pack from the charger. Again from Poly-Quest:
"If the PCM Guard detects that any one cell in the pack exceeds the limit it will electronically disconnect the pack from the charger and the warning LED light will go out on the PCM
Guard. Take a 3S for example. Even the best lithium polymer smart chargers, set properly by you, would want to charge this 3S pack to 12.6 volts. What happens when 2 cells
reach 4.2 volts each (ed. and the third cell doesn't)? The charger continues to charge trying to reach the 12.6 volts. Meanwhile, the 2 charged cells are being overcharged since the
charger doesn't think the pack is charged yet."