charging a 6v battery

Hi I am using 2 6V rechargeable LI-ion battery.I am not having any dc voltage source.Is it possible to charge by using bridge rectifier(with transformer of 220-15V step down and 1 amp current)for ac-dc conversion and then charge the two batteries(connected in series)with the available 15V dc?
If not please suggest me a good and cheaper method to charge.

BUY A REAL LI-ION CHARGER. Do NOT go cheap or you can make the batteries IGNITE!

Lithium ion batteries are VERY particular to the charging voltage & current used, and are intolerant of overcharging. Read about charging li-ion batteries here: Charging Lithium-ion -- Battery University

Here's a paragraph that exemplifies my concens:
"Lithium-ion operates safely within the designated operating voltages; however, the battery becomes unstable if inadvertently charged to a higher than specified voltage. Prolonged charging above 4.30V forms plating of metallic lithium on the anode, while the cathode material becomes an oxidizing agent, loses stability and produces carbon dioxide (CO2). The cell pressure rises, and if charging is allowed to continue the current interrupt device (CID) responsible for cell safety disconnects the current at 1,380kPa (200psi).

Should the pressure rise further, a safety membrane bursts open at 3,450kPa (500psi) and the cell might eventually vent with flame."

Don't burn your house down. Spend the money and buy the right equipment for the job. You can find 6V pack chargers for camera batteries for around S20US.