Despite considerable progress of silicon/carbon (Si/C) composites anodes, they still suffer from high irreversible capacity losses, which are mainly due to continuous Solid Electrolyte Interphase (SEI) layer formation, which consumes a large amount of lithium. To compensate for the active lithium losses, prelithiation of Si-based anodes has been attempted. In this manuscript, we report the effect of prelithiation on Si/C anodes combined with LiNi_0.5Mn_0.3Co_0.2O₂ cathodes in full cell configurations. To prepare Li_xSi/C anodes, Si/C electrodes were lithiated electrochemically at 0.1 and 0.5 V vs. Li/Li⁺ in half cell configuration before assembly of the full cell. Special attention is paid to the effect of the degree of prelithiation on initial electrochemical behavior and Li dendrite formation. In this work, electrochemical investigations were performed by using two-electrode and three-electrode measurements. Furthermore, the morphology of the active materials before and after cycling were characterized by post mortem Scanning Electron Microscopy (SEM).

Coating conducting polymers onto active cathode materials has been proven to mitigate issues at high current densities stemming from the limited conducting abilities of the metal-oxides. In the present study, a carbon coating was applied onto nickel-rich NMC622 via polymerisation of furfuryl alcohol, followed by calcination, for the first time. The formation of a uniform amorphous carbon layer was observed with scanning- and transmission-electron microscopy (SEM and TEM) and X-ray photoelectron spectroscopy (XPS). The stability of the coated active material was confirmed and the electrochemical behaviour as well as the cycling stability was evaluated. The impact of the heat treatment on the electrochemical performance was studied systematically and was shown to improve cycling and high current performance alike. In-depth investigations of polymer coated samples show that the improved performance can be correlated with the calcination temperatures. In particular, a heat treatment at 400 °C leads to enhanced reversibility and capacity retention even after 400 cycles. At 10C, the discharge capacity for carbon coated NMC increases by nearly 50% compared to uncoated samples. This study clearly shows for the first time the synergetic effects of a furfuryl polymer coating and subsequent calcination leading to improved electrochemical performance of nickel-rich NMC622.

Ordered mesoporous CuNiCo oxides were prepared via nanocasting with varied Cu/Ni ratio to establish its impact on the electrochemical performance of the catalysts. Physicochemical properties were determined along with the electrocatalytic activities toward oxygen evolution/reduction reactions (OER/ORR). Combining Cu, Ni, and Co allowed creating active and stable bifunctional electrocatalysts. CuNiCo oxide (Cu/Ni≈1 : 4) exhibited the highest current density of 411 mA cm⁻² at 1.7 V vs. reversible hydrogen electrode (RHE) and required the lowest overpotential of 312 mV to reach 10 mA cm⁻² in 1 m KOH after 200 cyclic voltammograms. OER measurements were also conducted in the purified 1 m KOH, where CuNiCo oxide (Cu/Ni≈1 : 4) also outperformed NiCo oxide and showed excellent chemical and catalytic stability. For ORR, Cu/Ni incorporation provided higher current density, better kinetics, and facilitated the 4e⁻ pathway of the oxygen reduction reaction. The tests in Li−O₂ cells highlighted that CuNiCo oxide can effectively promote ORR and OER at a lower overpotential.

The multifunctional electrolyte additive tris(trimethylsilyl)phosphite (TMSP) is investigated with a combination of operando gas chromatography/mass spectrometry and X‐ray photoelectron spectroscopy techniques, supported by cycling experiments and electrochemical impedance spectroscopy (EIS) measurements. Indications for hydrofluoric acid (HF) scavenging by TMSP could be found in the gas phase as well as on the electrode surfaces; however, it is observed that the use of TMSP leads to the production of HF, which it eventually scavenges. The investigation of the interphase formation shows that the decomposition products of TMSP are integrated into the interphases of both electrodes. This is accompanied by the formation of trimethylsilane as a decomposition product in the gas phase. TMSP also promotes the two‐electron reduction of ethylene carbonate (EC), which is deduced both from an increased amount of ethene in the gas phase and from Li₂CO₃ on the electrode surface. The electrochemical investigations show that cells with TMSP have a lower interphase resistance after continued cycling. However, only the cells with 1 wt% of TMSP in the electrolyte outperform the TMSP‐free reference cells. It is concluded that adding more than 1 wt% of TMSP increases the parasitic reactions of the additive to an extent that it partially counteracts its beneficial effect.