700 AHR Lithium Battery

 Yttrium Iron Phosphate batteries improve battery life, safety, and thermal characteristics. Iron phosphate is one of the safest batteries in the Lithium battery family mainly due to a strong oxygen bond with phosphorous that reduces thermal runaways at high voltages. Yttrium a rare earth metal is known for its thermal characteristics, most often used on high-performance spark plugs to reduce damage from heat and oxidation from elements under high temperature. Yttrium batteries operate at a lower voltage of 4.0 volts max and have a longer life than an LFP battery which operates as high as 4.2 volts and more prone to thermal runaways.  

700 AHA Data Sheet