Using DFT MD-simulations the origin of the Li-ion conductivity in argyrodite solid electrolytes is investigated. The simulations show that besides Li-ion vacancies in Li 6 PS 5 Cl and Li 6 PS 5 Br the influence of halogen atoms on their local surroundings also plays an important role in the Li-ion diffusion. The orders of magnitude difference in Li-ion conductivity between Li 6 PS 5 Cl and Li 6 PS 5 I is caused by the distribution of the halogen ions over the available crystallographic sites. This suggests that altering the halogen distribution in Li-argyrodites during synthesis could increase the Li-ion conductivity of these materials. For Li 6 PS 5 Cl the simulations predict an optimal Cldistribution of 1:3 over 4a-and 4c-sites, resulting in a Li-ion conductivity two times larger than the currently prepared materials. Based on these results simulations were performed on Li 5 PS 4 X 2 (X = Cl, Br or I), which show Li-ion conductivities similar to Li 6 PS 5 Cl and Li 6 PS 5 Br, suggesting that the Li 5 PS 4 X 2 compounds are interesting new compositions for solid state electrolytes.

One of the main challenges of all-solid-state Li-ion batteries is the restricted power density due to the poor Li-ion transport between the electrodes via the electrolyte. However, to establish what diffusional process is the bottleneck for Li-ion transport requires the ability to distinguish the various processes. The present work investigates the Li-ion diffusion in argyrodite Li6PS5Cl, a promising electrolyte based on its high Li-ion conductivity, using a combination of (7)Li NMR experiments and DFT based molecular dynamics simulations. This allows us to distinguish the local Li-ion mobility from the long-range Li-ion motional process, quantifying both and giving a coherent and consistent picture of the bulk diffusion in Li6PS5Cl. NMR exchange experiments are used to unambiguously characterize Li-ion transport over the solid electrolyte-electrode interface for the electrolyte-electrode combination Li6PS5Cl-Li2S, giving unprecedented and direct quantitative insight into the impact of the interface on Li-ion charge transport in all-solid-state batteries. The limited Li-ion transport over the Li6PS5Cl-Li2S interface, orders of magnitude smaller compared with that in the bulk Li6PS5Cl, appears to be the bottleneck for the performance of the Li6PS5Cl-Li2S battery, quantifying one of the major challenges toward improved performance of all-solid-state batteries.

Motion is a key characteristic of every form of life 1 . Even at the microscale, it has been reported that colonies of bacteria can generate nanomotion on mechanical cantilevers 2 , but the origin of these nanoscale vibrations has remained unresolved 3,4. Here, we present a novel technique using drums made of ultrathin bilayer graphene, where the nanomotion of single bacteria can be measured in its aqueous growth environment. A single E. coli cell is found to generate random oscillations with amplitudes of up to 60 nm, exerting forces of up to 6 nN to its environment. Using mutant strains, we are able to pinpoint the bacterial flagella as the main source of nanomotion. By real-time tracing of changes in nanomotion upon administering antibiotics, we demonstrate that graphene drums can perform antibiotic susceptibility testing with single-cell sensitivity. These findings deepen our understanding of processes underlying cellular dynamics, and pave the way towards high throughput and parallelized rapid screening of the effectiveness of antibiotics in bacterial infections with graphene devices.

Porous, atomically thin graphene membranes have interesting properties for filtration and sieving applications. Here, graphene membranes are used to pump gases through nanopores using optothermal forces, enabling the study of gas flow through nanopores at frequencies above 100 kHz. At these frequencies, the motion of graphene is closely linked to the dynamic gas flow through the nanopore and can thus be used to study gas permeation at the nanoscale. By monitoring the time delay between the actuation force and the membrane mechanical motion, the permeation time-constants of various gases through pores with diameters from 10–400 nm are shown to be significantly different. Thus, a method is presented for differentiating gases based on their molecular mass and for studying gas flow mechanisms. The presented microscopic effusion-based gas sensing methodology provides a nanomechanical alternative for large-scale mass-spectrometry and optical spectrometry based gas characterisation methods.

Motion is a key characteristic of every form of life. Even at the microscale, it has been reported that colonies of bacteria can generate nanomotion on mechanical cantilevers, but the origin of these nanoscale vibrations has remained unresolved. Here, we present a novel technique using drums made of ultrathin bilayer graphene, where the nanomotion of single bacteria can be measured in its aqueous growth environment. A single E. coli cell is found to generate random oscillations with amplitudes of up to 60 nm, exerting forces of up to 6 nN to its environment. Using mutant strains, we are able to pinpoint the bacterial flagella as the main source of nanomotion. By real-time tracing of changes in nanomotion upon administering antibiotics, we demonstrate that graphene drums can perform antibiotic susceptibility testing with single-cell sensitivity. These findings deepen our understanding of processes underlying cellular dynamics, and pave the way towards high throughput and parallelized rapid screening of the effectiveness of antibiotics in bacterial infections with graphene devices.