Extending the cycle life of porous micron-sized Silicon anodes by prelithiation

Peter Kalisvaart 1, B. Konersmann 2, Hyunsang Joo 2, E. Figgemeier 2, M. Spreafico 1, A. Schӧnecker 1, V. Ruiz* 1

1: E-magy B.V., Bijlestaal 54A, 1721 PW Broek op Langedijk, The Netherlands
2: Preli GmbH, Campus-Boulevard 79, 52074 Aachen, Germany
Helmholtz-Institute Münster (HI MS): Ionics in Energy Storage (IMD-4), Forschungszentrum Jülich GmbH, Corrensstrasse 46, D-48149 Münster, Germany
*vanesa.ruiz@e-magy.com

Silicon is a key enabler of future high-energy-density lithium-ion batteries (LIBs). E-magy’s nanoporous, micron-sized silicon offers a silane-free route to LIB anodes with strongly reduced expansion [1], potentially greatly simplifying battery cell engineering. However, even in the absence of intrinsic material degradation by fracture, cycle lifetime of a full cell is limited by progressive electrolyte decomposition, which immobilizes an ever-greater part of the active lithium.
The initial lithium inventory of a battery can be increased by prelithiation of the anode, providing a greater Li reservoir to mitigate the effects of Li consumption by electrolyte decomposition [2]. Another mechanism of action of the prelithiation step is reducing the reactivity between Si and the electrolyte by pre-forming a solid electrolyte interphase (SEI). Furthermore, Si is most reactive at low Li-content, above 0.75 V vs. Li [3], and a sufficient extent of prelithiation will keep the anode voltage below this value even in the fully discharged state of the battery.

Prelithiation of anode sheets produced with E-magy’s porous Silicon has been conducted on a small-scale commercial pilot line. Three prelithiation depths have been tested: 370, 540 and 610 mAh/gSi. A cycle life extension of more than a factor 2 was achieved for a LixSiNMC622 cell, where ‘x’ corresponds to a prelithiation degree of 540 mAh/gSi:

Figure 1: Capacity retention vs. cycle # for micron-sized LixSi//NMC622 full cell with different degree of anode prelithiation. Cycle life extension is > factor 2

Prelithiation in an industrially relevant setup has thus been successfully demonstrated for our micron-sized porous silicon material. Further improvements are expected from electrolyte optimization, both in the prelithiation bath and during cycling.

[1] F. Maroni, M. Spreafico, A. Schönecker, M. Wohlfahrt-Mehrens, M. Marinaro, Journal of the Electrochemical Society, vol. 169, Issue 8, 080506 (2022)

[2] S. Li, J. Jiang, Y. Zheng, Z. Ju, Q. Zhuang, K. Wu, H. Shao, X. Zhang, Batteries&Supercaps, vol. 7, Issue 7, e202400115 (2024)

[3] J.D. McBrayer, N.B. Schorr, M.N. Lam, M.L. Meyerson, K.L. Harrison, S.D. Minteer, ACS Appl. Mater. Interfaces, vol. 16, Issue 15, 19663−19671 (2024)