Today, lithium-ion batteries (LIB)/ grid-scale battery storage is one of the fastest-growing energy storage systems globally with China, US and Europe leading the market (Schoenfisch & Dasgupta, 2022) (Figure 1). Although the global economy plunged in 2020 due to the COVID pandemic, the battery market continued to grow exponentially. Between 2020 and 2021, the grid-scale battery storage market saw an annual increase of over 60% in global storage capacity (Schoenfisch & Dasgupta, 2022). 

Figure 1: Annual grid-scale battery storage additions and distribution (Schoenfisch & Dasgupta, 2022)

In spite of the rapid growth in grid-scale battery storage, the global capacity remains undesirably low should we want to reach a net zero scenario. To meet the goal, Schoenfisch & Dasgupta (2022) estimate that the global grid-scale battery storage capacity will have to increase to 680 GW by 2030 (Figure 2). 

Figure 2: Required annual increase of gird-scale battery storage to meet the net zero scenario (Schoenfisch & Dasgupta, 2022)

Although LIB is an excellent alternative and direction towards a low-carbon future, the gaps and problems these batteries continue to plague the industry. The most pressing problem these batteries have today is their sensitivity to high temperatures and susceptibility to burn (Ghiji et al., 2020) (Figure 3). There are a few ways a LIB can be ignited, they include short-circuit, overcharging, exposure to high temperature, mechanical stress and more (Larsson et al., 2017). The hazardous nature of these batteries is particularly risky when used in vehicles such as electrical vehicles and aeroplanes (Ghiji et al., 2020). 

Figure 3: Electric car on fire (Ghoshal, 2021)

According to Larsson et al. (2017), the electrolyte of LIBs often contains lithium hexafluorophosphate (LiPF6) or other Li-salts containing fluorine, which are highly flammable and reactive compounds (Guo et al., 2020). Furthermore, fluorine is commonly found in other parts of the LIB in components such as fire retardants and electrodes (Larsson et al., 2017). Being one of the lightest and most reactive metals, this makes LIBs extremely vulnerable to high temperatures and combustion. 

Besides the immediate thermal damage from burning, LIBs also release toxic gases such as carbon monoxide (CO) and hydrogen fluoride (HF) (Zhang et al., 2022). The decomposition of LiPF6 is further exacerbated when water is used as an extinguisher (Larsson et al., 2017). 

LiPF6  → LiF + PF5 – (1)

PF5 + H2O + → POF3 + 2HF – (2)

LiPF6 + H2O → LiF + POF3 + 2HF – (3)

Additionally, the composition of toxic gases released between different batteries varies according to the particular chemical composition and state of charge (SOC) of each battery (Larsson et al., 2017). The volume and threat of toxic gases released are also larger for bigger cell packs (Larsson et al., 2017). When a large amount of electrolyte evaporates when batteries are heated, this gas may not ignite immediately when released but may accumulate and result in gas explosions at later stages (Larsson et al., 2017). 

In the coming blogs, I will explore the toxic gases produced from the combustion of LIBs in detail so stay tuned for more!

 

Reference List

Ghiji, M., Novozhilov, V., Moinuddin, K., Joseph, P., Burch, I. A., Suendermann, B., & Gamble, G. (2020). A Review of Lithium-Ion Battery Fire Suppression. Energies, 13(19), 5117. https://doi.org/10.3390/en13195117 

Ghoshal, A. (2021, December 15). How Lithium Ion batteries in EVs catch fire – Adreesh Ghoshal – Medium. Medium. https://adreesh-ghoshal.medium.com/how-lithium-ion-batteries-in-evs-catch-fire-9d166c5b3af1 

Guo, F., Ozaki, Y., Nishimura, K., Hashimoto, N., & Fujita, O. (2020). Influence of lithium salts on the combustion characteristics of dimethyl carbonate-based electrolytes using a wick combustion method. Combustion and Flame, 213, 314–321. https://doi.org/10.1016/j.combustflame.2019.12.001 

Larsson, F., Andersson, P., Blomqvist, P., & Mellander, B. (2017). Toxic fluoride gas emissions from lithium-ion battery fires. Scientific Reports, 7(1). https://doi.org/10.1038/s41598-017-09784-z 

Schoenfisch, M., & Dasgupta, A. (2022, September). Grid-Scale Storage – Analysis – IEA. IEA. https://www.iea.org/reports/grid-scale-storage 

Zhang, L., Duan, Q., Meng, X., Jin, K., Xu, J., Sun, J., & Wang, Q. (2022). Experimental investigation on intermittent spray cooling and toxic hazards of lithium-ion battery thermal runaway. Energy Conversion and Management, 252, 115091. https://doi.org/10.1016/j.enconman.2021.115091