A ECO-LFP210 10Ah 4S LiFePo4 battery was purchased on eBay for a solar powered project, cost about $65 delivered.
Above, the battery (the Anderson Power Pole connector is an addition). The battery incorporates a battery management system (BMS), so protected against over voltage, undervoltage, over current, and cell balance is preserved.
The battery was charged, then discharged, charged again and discharged, all at 2A (0.2C).
Above is a plot of the two discharge cycles.
It delivered more than the rated 10Ah on both tests.
Specs are printed on the battery.