This SparkFun Real Time Clock (RTC) Module is a Qwiic-enabled breakout board for the RV-1805 chipset. The RTC is ultra-low power (running at only about 22nA in its lowest power setting) so it can use a supercapacitor for backup power instead of a normal battery. This means you get plenty of charge and discharge cycles without any degradation to the “battery.“ The supercap can hypothetically make the board keep time for around 35 days.
This RTC module’s built in RV-1805 has not one, but two internal oscillators: a 32.768kHz tuning fork crystal and a low power RC based oscillator and can automatically switch between the two using the more precise crystal to correct the RC oscillator every few minutes. This feature allows the module to maintain a very accurate date and time with the worst case being +/- about three minutes over a year.
More information is available on the website of Sparkfun.