Cathode pre-lithiation/sodiation for next-generation batteries

Electrochemical energy storage is playing a pivotal role in the global pursuit of a clean and sustainable energy future. Lithium-ion batteries (LIBs) are the state-of-the-art technology, but future energy requirements demand higher energy densities and a more diverse battery landscape to meet a wide variety of applications. Unfortunately, many next-generation LIB chemistries and beyond-LIB technologies suffer from large first-cycle irreversible capacity caused by active ion loss. The field of pre-lithiation/sodiation has recently emerged as researchers attempt to mitigate active ion loss and boost the energy density of next-generation LIBs and sodium-ion batteries. In this short review, we highlight recent advances in cathode pre-lithiation/sodiation using sacrificial additives and pre-lithiation/sodiation of cathode active materials.     

Comparison of Low-Energy Neutral Scattering (LENS) with Low-Energy Ion Scattering (LEIS) at clean and adsorbate covered Ni surfaces

Ne and He projectiles were scattered at clean and sulphur or oxygen-covered polycrystalline Ni surfaces. The analysis of backscattered neutrals results in an oxygen to nickel surface atom density of 0.7 for NiO and a sulphur to nickel density of 0.25 for a saturation coverage of sulphur on polycrystalline nickel, which is in good accord with expectation. Only differential scattering cross-sections, which can be calculated with sufficient reliability enter the data reduction. This is a definite advantage over ion scattering which is complicated by the widely unknown neutralization probabilities.     

VUV isochromat spectroscopy

A highly sensitive isochromat spectrometer employing a frequency selective helium iodine Geiger Müller photoncounter is described. The overall resolution of ±0.36 eV at an average quantum energy of 9.6 eV compares favourably with conventional set-ups. Sample data for a polycrystalline tantal target show satisfactory agreement with earlier experiments.     

Electron production by metastable rare gas atom impact on a molybdenum (110) surface

Electron production by impact of thermal energy metastable helium, argon, and xenon atoms on a molybdenum (110) surface was studied. The electron yield was always highest for a clean surface and decreased considerably when the surface was exposed to either oxygen or carbon monoxide. The change in electronic yield with gas coverage of the surface was most drastic for xenon and smallest for helium metastables. The similarity of the present results to earlier measurements of electron production by low energy noble gas ion impact led us to believe that metastable deexcitation proceeded via resonance ionization followed by Auger neutralization in the present cases.     

Critical point energies from appearance potential spectra of cobalt,nickel, and copper

Structural features in soft X-ray appearance potential spectra (SXAPS) of cobalt, nickel, and copper previously assigned to collective excitations are shown to be due to corresponding structure in the s-p like density of states of these metals. By reference to theoretical work the critical points in the f.c.c. Brillouin zone responsible for these features are identified and experimental critical point energies are derived and compared to various band structure calculations.     

The effect of environment on cystine disruption by ultraviolet light

When cystine is irradiated at pH 1 by 254-nm u.v. the following yields are observed: 4 cystines → 5.2 cysteines + 2.8NH₃. Thus, SH production accounts for only 0.65 of the cystine destruction; further C-S breakage to give alanine or serine is not efficient. The yields for cystine and glutathione destruction are essentially the same at pH 1. However the presence of the glutamic and glycine residues stabilize the cystine in glutathione so that NH₃ is not lost until the peptide bonds are hydrolyzed. Increasing the pH from 1 to 8.6 increases the yield of cystine destruction in glutathione by 50 per cent. The yield of cystine destruction is greater in both compounds when O₂ is present during irradiation (e. g. the cysteic acid yield in glutathione is increased by 50 times). The overall production of SH varies by a factor of 2 in the four proteins-insulin, RNase, trypsin and lysozyme. The present data further support the earlier observation that radiation damage is quite non-random in RNase: at least two and perhaps three of the four constituent cystines must be disrupted before activity is lost: i.e. the most radiosensitive cystines are not critical for enzymic activity. Similarly, in both trypsin and lysozyme the integrity of the most radiosensitive cystines also does not appear to be critical for the retention of enzymic potential. In insulin, however, all three cystines appear to be crucial for activity and to have approximately equal radiosensitivities. These differences in sensitivity of cystines in different proteins must depend specifically upon energy transfer and/or chemical interactions between the chromophoric groups. If yields are calculated on the basis of those quanta absorbed only in the cystines, values about 5 to 8 times greater than those in the model compounds cystine and oxixized glutathione are obtained. The yields of cystine destruction are much higher in those protiens which contain trypotophan.