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Importance of capacity balancing on the electrochemical performance of Li[Ni0.8Co0.1Mn0.1]O-2 (NCM811)/Silicon full cells

Wichtigkeit der Kapazitätsbalanzierung auf die elektrochemische Performance von Li[Ni0.8Co0.1Mn0.1]O2 (NCM811)/Silizium-Vollzellen
: Reuter, Florian; Baasner, Anne; Pampel, Jonas; Piwko, Markus; Dörfler, Susanne; Althues, Holger; Kaskel, Stefan

Fulltext ()

Journal of the Electrochemical Society 166 (2019), No.14, pp.A3265-A3271
ISSN: 0013-4651
ISSN: 1945-7111
ISSN: 0096-4786
Bundesministerium für Bildung und Forschung BMBF (Deutschland)
03XP0130D; ProSiSt
Journal Article, Electronic Publication
Fraunhofer IWS ()
lithium ion battery; amorphus-silicon; degradation phenomena; dendrite formation; cathode material; Si particles; Anode; electrode; density; composite; Lithium-Ionen-Batterie; Li[Ni0.8Co0.1Mn0.1]O2 Kathode; kolumnare Silizium Anode; Balanzierung; Batterie; 3-Elektroden Messung

In recent years, both silicon thin films and nickel-rich layered oxides have received much attention as promising anode or cathode materials for next generation lithium ion batteries, respectively. In this work, full cells containing Li[Ni0.8Co0.1Mn0.1]O-2 (NCM811) as cathode in combination with amorphous columnar silicon thin films as anode are evaluated in coin cells and 3-electrode cells with varying capacity balancing. Full cells with area capacity ratios of negative to positive electrodes (n/p-ratio) reaching from 1.15 : 1 to 2.70 : 1 are studied. The cells with a high n/p-ratio (2.00 : 1 and 2.70 : 1) show significantly lower specific capacity of 115 mA h g(NCM)(-1) after 50 cycles of galvanostatic cycling in comparison to 130 mA h gNCM-1 for a cell with a n/p-ratio of 1.15 : 1. One reason for this phenomenon is the decline of the initial coulombic efficiency with increasing n/p-ratios. Secondly, through only partial utilization of the silicon anode by using high n/p-ratios, the anode potential is increased at the end of charge. This leads to a higher cathode potential and therefore a faster degradation of the cell. In summary, for designing high performance NCM811/Si full cells, high n/p-ratios should be avoided.