Increased Energy Density and Cycle Life through Direct Contact Prelithiation

Summary:

Nowadays, lithium-ion batteries are the technology of choice for many applications in the field of consumer electronics and electric mobility. To meet the requirements for the application in electric vehicles, lithium-ion battery technology has many challenges to overcome related to energy density, lifetime, and overall costs. New materials, electrode designs, and production processes for lithium-ion battery cells are currently the subject of scientific studies and represent a significant factor in meeting these challenges.
To increase energy density and cycle life, prelithiation is a proven method on a laboratory scale, which describes the addition of lithium to the battery cell during production [1]. The addition of lithium compensates for the initial loss of capacity, which is mainly caused by the formation of the solid electrolyte interface (SEI) during the first charge and discharge cycles. In addition to the initial capacity loss, lithium-ion batteries suffer from capacity losses during cell operation. Especially, innovative anode materials, such as silicon and silicon-graphite composites, suffer from high cyclic losses due to repeated breaking and re-forming of the SEI [2]. Through prelithiation, a lithium reservoir is introduced into the cell, which reduces these cyclic capacity losses.
To date, various prelithiation techniques have been evaluated, including electrochemical prelithiation, chemical prelithiation, prelithiation via additives, and prelithiation by direct contact with lithium metal. Due to its flexible application, compatibility with common electrode materials, scalability, and cost-efficiency direct contact prelithiation is a promising method for the application on an industrial scale.

Within the presentation, the principle of prelithiation and different prelithiation methods are described, as well as the advantages of using direct contact prelithiation within lithium-ion battery production. Therefore, its effect on the electrochemical performance is shown using lithium-ion cells with silicon-graphite composite anodes. The results presented show that direct contact prelithiation can increase the energy density of LIB of different electrode materials by up to 30% and the cycle life by more than 50%. Due to the promising electrochemical results, a roll-to-roll approach to implement direct contact prelithiation into the industrial production of lithium-ion batteries is presented [3].

References

[1] Chevrier, V.L., Liu, L., Wohl, R., Chandrasoma, A. et al., 2018. Design and Testing of Prelithiated Full Cells with High Silicon Content 165, A1129-A1136.
[2] Wetjen, M., Pritzl, D., Jung, R., Solchenbach, S. et al., 2017. Differentiating the Degradation Phenomena in Silicon-Graphite Electrodes for Lithium-Ion Batteries 164, A2840-A2852.
[3] Stumper, B., Mayr, A., Reinhart, G., 2020. Application of Thin Lithium Foil for Direct Contact Prelithiation of Anodes within Lithium-Ion Battery Production, Procedia CIRP 93 (2020) 156–161