How do I recharge a battery using a small solar cell
Your solar cell, assuming the larger value of 2 microamps, can provide a power of 1 volt X 2 microamps = 2 microwatts. To provide enough energy to recharge a 2.7 Wh battery would take a minimum of 1.35 million hours (not even allowing for less than 100% efficiency in getting the solar cell energy into the battery). It should be clear that you need to get a much larger solar cell to accomplish your purpose.