Compare lithium-ion and flow battery technologies for grid storage.

Lithium-ion: high energy/power density, established supply chain, 85-95% efficiency, 10-15 year life, declining costs ($150-300/kWh), best for 1-4 hour duration, fire safety concerns require BMS and thermal management. Flow batteries (vanadium, zinc-bromine): energy and power independently scalable (add more electrolyte for duration), 20+ year life, 65-80% efficiency, minimal degradation, safer chemistry, higher capital cost but lower cycle cost, best for 4-12+ hour duration. Selection depends on application: power-focused (Li-ion) vs energy-focused (flow).