Finally there is viable alternative to Ipower 9V Lithium Ion batteries.

9V 550mAh Lithium Polymer Rechargeable Battery are the newest addition to the Stryka range. Specifically designed to meet the demand of sound and audio professionals. 

Years of R&D have gone into testing our Stryka 9V Lithium batteries for cordless mics. We have packed as much power as possible into this battery whilst still maintaining the reliability and performance that professionals demand. Don't be fooled by other companies misleading "nominal" Ah ratings. Some claiming up to 700mAh!! There is only so much power you can pack into this size battery with this chemistry and have it still performing safely and reliably. Believe us we tried and tried for years as we wanted to have something higher than 550mAh to blow the competition away!!