Because of their high-gravimetric capacities, use of Si-containing anodes in Li-ion batteries can lead to a big jump in energy densities. The control of lithium consumption, however is a big obstacle for these cells, and many strategies are emerging to address the problem of Li inventory. We search for solutions on the subject from two fronts. The first is to understand the lithium inventory via utilization of a quasi-RE/CE thick LiFePO₄ in a Si-type full cell [1-2]. In this study we show the effectiveness of LiFePO₄ as a diagnostic tool in order to assay the quantity of Li consumption in a full cell as marked by the percent loss of lithium per cycle via SEI growth and/or SEI consumption and re-formation. This approach allows the Li content to be followed during cycling without Li metal or layered oxide cathode complications (i.e. non-controlled voltage shifts). The second topic focuses on practical solutions to introduce high contents of Li into the cell in the easiest, most straightforward way. We take the approach of designing cathodes and utilizing cathode blends wherein sacrificial Li is introduced into the cell [3]. In these cases greater energy densities can be realized from higher retained cathode capacity, and cycle life is dramatically improved.

1. “Capacity fade in high energy silicon-graphite electrodes for lithium-ion batteries”, W. M. Dose, M. J. Piernas-Munoz, V. A. Maroni, S. E. Trask, I. Bloom and C. S. Johnson, Chemical Communications, (2018), 54, 3586-3589
2. “Assessment of Li-Inventory in cycled Si-Graphite anodes using LiFePO₄ as a diagnostic cathode”, W. M. Dose, V. A. Maroni, M. J. Piernas-Munoz, S. E. Trask, I. Bloom, and C. S. Johnson, J. Electrochem. Soc., (2018), 165, A2389-A2396
3. “Mitigating the initial capacity loss and improving the cycling stability of silicon monoxide using Li₅FeO₄”, L. Zhang, W. M. Dose, A. D. Vu, C. S. Johnson, W. Lu, J. Power Sources, (2018), 400, 549-555.