• Cell format: 21700 (≈ 21 mm diameter × 70 mm length) cylindrical Li-ion cell.
• Nominal capacity: 5,000 mAh (5 Ah) at around ~3.6–3.7 V. For example, Sunpower lists “5000mAh 3.6 V / 6C high rate lithium-ion Battery 50SE”. sunpowernewenergy.com+2Alibaba+2
• Discharge rate: “6C” (so theoretically up to ~30 A continuous discharge, since 6 × 5 A = 30 A). For example, the 50SE model is said to support “continuous discharge current is 30A” for that version. sunpowernewenergy.com
• Charge/Discharge cut-off and typical voltage range:
  • Full charge voltage: ~4.2 V (typical for many Li-ion)
  • Nominal voltage: ~3.6–3.7 V
  • Discharge cut-off: around 2.5 V (in some specification) sunpowernewenergy.com+1
• Cycle life: The datasheet or marketing claims vary. For example, on one Alibaba listing this Sunpower 5000 mAh 21700 battery says “1000 cycles”. Alibaba The standard overview for 21700 cells indicates typical cycle life in the “800–1000+ cycles” range under good conditions. battsysbattery.com+1
• Temperature / high-rate / durability features: The 50SE model claims high-temperature tolerance: may be stored/used in high T environments (charging above 45 °C, discharge above 60 °C) and says cell swelling <2%, no fire/explosion at 120 °C in some tests. sunpowernewenergy.com
• Certifications: The manufacturer claims certifications like UL/CB/SGS/BIS/PSE/KC/UN38.3 etc for that model.