# A Simplified Analysis to Predict the Fire Hazard of Primary Lithium Battery
## 1 Introduction  
Lithium batteries are widely used in electronic products as they are highly energy-dense electrochemical cells. There are two kinds of lithium battery: the primary lithium battery, also called a lithium metal battery, and the secondary lithium battery, also called a lithium-ion battery. Primary lithium batteries have lithium metal or lithium compounds as the anode. By comparison, the lithium-ion battery is a member of the rechargeable battery family. Primary lithium batteries are commonly used in portable consumer electronic devices and in electric vehicles, ranging from full sized vehicles to radio controlled toys. The most widely used primary lithium battery is the lithium/manganese dioxide (MnO\({}_{2}\)) couple. Lithium-ion batteries are common in consumer electronics. They are one of the most popular types of rechargeable battery for portable electronics, with one of the best energy densities, no memory effect, and only a slow loss of charge when not in use. In addition to consumer electronics, lithium-ion batteries are growing in popularity for military, electric vehicle, and aerospace applications. The mostly popular lithium-ion batteries are based on lithium cobalt oxide (LCO), lithium iron phosphate (LFP), lithium manganese oxide (LMO), and lithium nickel manganese cobalt oxide (NMC). All lithium batteries contain highly flammable organic solvents and potentially explosive components [1]. Many fire and explosion lithium battery accidents have occurred in the past and knowledge of appropriate fire protection agents has not kept pace with the industrial use of lithium batteries, which has grown substantially over the past few years [2; 3]. Many past studies focused on the safety aspects of lithium batteries in relation to their components, such as electrode materials, the separator, the component of electrolyte, and its additives; to the structure of battery; and the manufacturing process [4; 5; 6]. Studies on other hazards of lithium batteries have been conducted on the overcharge, nail penetration, crush, and internal short circuit [7; 8; 9]. Fire behaviors of primary lithium and lithium-ion batteries have been more recently investigated [10; 11]. The thermal runaway is thought to be the main cause of fire and explosion in lithium-ion batteries [12; 13; 14]. The burning of lithium batteries produces toxic gases such as HF, CO, and SO\({}_{2}\), which threaten health [15; 16]. [PERSON] et al. studied the combustion of a single 2.9 Ah LiMn\({}_{2}\)O\({}_{4}\) battery to investigate the process of battery fire, and found that the state of charge (SOC) significantly affected the burning behavior [17]. [PERSON] et al. performed similar fire research to evaluate the safety of a large lithium-iron phosphate/graphite battery with 50 Ah capacity and significant fire hazards were also observed [18]. [PERSON] et al. conducted fire tests on commercial lithium iron phosphate batteries [19]. [PERSON] et al. conducted an experimental study on the burning behaviors of 18,650 lithium-ion batteries, and evaluated the effects of SOC on burning behaviors of lithium-ion batteries [20]. According to their studies, SOC is the main factor affecting the thermal runaway and sustained fire. The SOC of a lithium-ion battery can significantly affect the burning behaviors, and it is generally thought that batteries with larger SOC have a greater ability to burn or explode [21; 22; 23; 24]. Normally, higher SOC batteries produce higher heat release rate peaks and higher total HF emission than lower SOC batteries. Batteries are rarely stored and transported as single batteries, and the burning behavior of a pile of multiple batteries can be drastically different from that of a single one. When lithium batteries catch fire, especially during air transport and storage, they can be extraordinarily hazardous. International Air Transport Association Dangerous Goods Regulations (IATA DGR) had introduced special rules about lithium battery transport for the prevention of fire and explosion.