DIY LITHIUM BATTERY FOR BEGINNERS

Lithium batteries stand apart from other battery chemistries due to their high energy density and low cost per cycle. However, "lithium battery" is an ambiguous term. There are about six common chemistries of lithium batteries, all with their own unique advantages and disadvantages. For renewable energy applications, the predominant chemistry is Lithium Iron Phosphate (LiFePO4). This chemistry has excellent safety, with great thermal stability, high current ratings, long cycle life, and tolerance to abuse.
Lithium Iron Phosphate (LiFePO4) is an extremely stable lithium chemistry when compared to almost all other lithium chemistries. The battery is assembled with a naturally safe cathode material (iron phosphate). Compared to other lithium chemistries iron phosphate promotes a strong molecular bond, which withstands extreme charging conditions, prolongs cycle life, and maintains chemical integrity over many cycles. This is what gives these batteries their great thermal stability, long cycle life, and tolerance to abuse. LiFePO4 batteries are not prone to overheating, nor are they disposed to 'thermal runaway' and therefore do not over-heat or ignite when subjected to rigorous mishandling or harsh environmental conditions.
Unlike flooded lead acid and other battery chemistries, Lithium batteries do not vent dangerous gases such as hydrogen and oxygen. There's also no danger of exposure to caustic electrolytes such as sulfuric acid or potassium hydroxide. In most cases, these batteries can be stored in confined areas without the risk of explosion and a properly designed system should not require active cooling or venting.