Lead-Acid (AGM / Gel / Flooded) vs. Lithium Thionyl Chloride (Li-SOCl2)
Comparing 2 standards across 9 specifications. 9 key differences identified.
Lead-Acid is the oldest rechargeable battery chemistry (invented 1859), delivering 2.0V per cell (12V nominal in standard 6-cell monoblocs). Despite low gravimetric energy density (30–50 Wh/kg), its unmatched surge current delivery (hundreds of cold cranking amps), low production cost, and 99% recycling rate make it the universal standard for automotive starting/ignition (SLI) and industrial UPS systems.
Lithium Thionyl Chloride (Li-SOCl2) is an ultra-high-density industrial primary chemistry delivering 3.6V nominal per cell. With gravimetric energy density reaching 650–700 Wh/kg, exceptional temperature tolerance (-60°C to +85°C), and an ultra-low self-discharge rate (<1% per year), it provides 15-to-20+ years of maintenance-free operational life in utility meters, oceanographic sensors, and defense hardware.
Specification Comparison Table
9 Parameters| Parameter / Spec | ||
|---|---|---|
|
Nominal Cell Voltage
|
2.00 (12.00 V 6-Cell Pack) V | 3.60 V |
|
Gravimetric Energy Density
|
30 – 50 Wh/kg | 600 – 700 Wh/kg |
|
Volumetric Energy Density
|
60 – 100 Wh/L | 1,000 – 1,300 Wh/L |
|
Cycle Life (to 80% Capacity)
|
300 – 1,000 (Deep Cycle AGM) Cycles | Single Use (Primary 20-Year Operational Life) |
|
Thermal Runaway Threshold
|
> 200 °C | > 180 °C |
|
Operating Temperature Range
|
-20 to +50 °C | -60 to +85 °C |
|
Self-Discharge Rate
|
3 – 5% / Month | < 1% / Year (15–20 Year Shelf Life) |
|
Primary Anode Material
|
Porous Sponge Lead (Pb) | Metallic Lithium Foil (Li) |
|
Primary Cathode Material
|
Lead Dioxide (PbO2) in Sulfuric Acid Electrolyte (H2SO4) | Liquid Thionyl Chloride (SOCl2) with Porous Carbon Current Collector |