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Solid-state Li-ion conductors are of broad interest in electrochemical energy storage, especially in solid-state Li batteries that serve as a promising alternative for the next-generation safe and high-energy-density batteries. Exploring solid-state superionic conductors is significant for the development of solid-state Li batteries with high performance. Herein, we report a disordered rock-salt (A 1 B 1 )-structured solid electrolyte (Li 0.625 Al 0.125 H 0.25 )­(Cl 0.75 O 0.25 ) (abbr. LAHCO) that was synthesized using Li 2 OHCl and LiAlCl 4 as precursors. Neutron diffraction reveals that Li, Al, and H atoms occupy the A sites and O and Cl atoms occupy the B sites in the A 1 B 1 structure for pure LAHCO. The LAHCO compound with excess LiAlCl 4 shows the highest Li + ionic conductivity of ∼10 –4 S cm –1 at room temperature due to the disordering induced by configurational entropy as well as the entropy of mixing. Moreover, LAHCO–LiAlCl 4 solid electrolyte exhibits a stable polarization voltage under a current density of 5–50 μA cm –2 in Li symmetric cells. This work not only explicates the importance of Li-ion conductors with a rock-salt structure but also contributes toward the development of solid-state Li-ion conductors for broad applications.

Neutron and electron spectroscopy reveal diffusion behavior of individual ions in lithium garnets, paving the way towards high-performance aqueous lithium batteries.

AbstractThe electroreduction of C1 feedgas to high-energy-density fuels provides an attractive avenue to the storage of renewable electricity. Much progress has been made to improve selectivity to C1 and C2 products, however, the selectivity to desirable high-energy-density C3 products remains relatively low. We reason that C3 electrosynthesis relies on a higher-order reaction pathway that requires the formation of multiple carbon-carbon (C-C) bonds, and thus pursue a strategy explicitly designed to couple C2 with C1 intermediates. We develop an approach wherein neighboring copper atoms having distinct electronic structures interact with two adsorbates to catalyze an asymmetric reaction. We achieve a record n-propanol Faradaic efficiency (FE) of (33 ± 1)% with a conversion rate of (4.5 ± 0.1) mA cm−2, and a record n-propanol cathodic energy conversion efficiency (EEcathodic half-cell) of 21%. The FE and EEcathodic half-cell represent a 1.3× improvement relative to previously-published CO-to-n-propanol electroreduction reports.

Strong metal–support interactions (SMSIs) and catalyst deactivation have been heavily researched for decades by the catalysis community. The promotion of SMSIs in supported metal oxides is commonly...

Solid electrolytes (SEs) are widely considered as an ‘enabler’ of lithium anodes for high-energy batteries. However, recent reports demonstrate that the Li dendrite formation in Li7La3Zr2O12 (LLZO) and Li2S–P2S5 is actually much easier than that in liquid electrolytes of lithium batteries, by mechanisms that remain elusive. Here we illustrate the origin of the dendrite formation by monitoring the dynamic evolution of Li concentration profiles in three popular but representative SEs (LiPON, LLZO and amorphous Li3PS4) during lithium plating using time-resolved operando neutron depth profiling. Although no apparent changes in the lithium concentration in LiPON can be observed, we visualize the direct deposition of Li inside the bulk LLZO and Li3PS4. Our findings suggest the high electronic conductivity of LLZO and Li3PS4 is mostly responsible for dendrite formation in these SEs. Lowering the electronic conductivity, rather than further increasing the ionic conductivity of SEs, is therefore critical for the success of all-solid-state Li batteries. Despite its importance in lithium batteries, the mechanism of Li dendrite growth is not well understood. Here the authors study three representative solid electrolytes with neutron depth profiling and identify high electronic conductivity as the root cause for the dendrite issue.

High voltage cathode materials Li-excess layered oxide compounds Li[NixLi1/3−2x/3Mn2/3−x/3]O2 (0 < x < 1/2) are investigated in a joint study combining both computational and experimental methods. The bulk and surface structures of pristine and cycled samples of Li[Ni1/5Li1/5Mn3/5]O2 are characterized by synchrotron X-Ray diffraction together with aberration corrected Scanning Transmission Electron Microscopy (a-S/TEM). Electron Energy Loss Spectroscopy (EELS) is carried out to investigate the surface changes of the samples before/after electrochemical cycling. Combining first principles computational investigation with our experimental observations, a detailed lithium de-intercalation mechanism is proposed for this family of Li-excess layered oxides. The most striking characteristics in these high voltage high energy density cathode materials are 1) formation of tetrahedral lithium ions at voltage less than 4.45 V and 2) the transition metal (TM) ions migration leading to phase transformation on the surface of the materials. We show clear evidence of a new spinel-like solid phase formed on the surface of the electrode materials after high-voltage cycling. It is proposed that such surface phase transformation is one of the factors contributing to the first cycle irreversible capacity and the main reason for the intrinsic poor rate capability of these materials.