What is the proven method to boost lithium ion battery technology? The answer lies on inserted-compound of cathodes and anodes. Also organic liquid electrolytes like LiPF6 salt dissolved in a mixture of organic solvents. Such as ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). The most dominated anode in commercial lithium ion cells is graphite. This material already used for the past 25 years in battery industry. The reason is because graphite has an operating voltage close to lithium ion (~ 0.1V) with 372 Ah/kg capacity. For further, graphite also has a corresponding to the insertion of one Li per six carbon atoms to shape LiC6 (figure 1).
Figure 1. Crystal structure of graphite LixC6 (ACS Central Science, 2017).
Furthermore, anode with graphite provides the stability for its operation with a long life. This condition happens due to the formation of a stable solid electrolyte interphase (SEI) layer on the graphite surface during the reaction with electrolyte solvents. However, the slow lithium diffusion ion transfer through the SEI could cause lithium dendrite formation (condition when extra lithium ions accumulate and can not be absorbed) on the anode graphite surface. This situation possibly cause internal short circuit that lead to catastrophic safety hazards. It particularly happens on fast charge condition with low temperatures. For avoiding the anode lithium dendrite, scientist still work on alternative insertion reaction anode. This method also will keep the graphite anode from reducing the cell energy density drastically.
|Date||:||11 May 2021|