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Lithium-ion-conducting solid electrolytes hold promise for enabling high-energy battery chemistries and circumventing safety issues of conventional lithium batteries. Achieving the combination of high ionic conductivity and a broad electrochemical window in solid electrolytes is a grand challenge for the synthesis of battery materials. Herein we show an enhancement of the room-temperature lithium-ion conductivity by 3 orders of magnitude through the creation of nanostructured Li(3)PS(4). This material has a wide electrochemical window (5 V) and superior chemical stability against lithium metal. The nanoporous structure of Li(3)PS(4) reconciles two vital effects that enhance the ionic conductivity: (1) the reduction of the dimensions to a nanometer-sized framework stabilizes the high-conduction β phase that occurs at elevated temperatures, and (2) the high surface-to-bulk ratio of nanoporous β-Li(3)PS(4) promotes surface conduction. Manipulating the ionic conductivity of solid electrolytes has far-reaching implications for materials design and synthesis in a broad range of applications, including batteries, fuel cells, sensors, photovoltaic systems, and so forth.

We report herein a hierarchically structured sulfur-carbon (S/C) nanocomposite material as the high surface-area cathode for rechargeable lithium batteries. A porous carbon with a uniform distribution of mesopores of 7.3 nm has been synthesized through a soft-template synthesis method. The potassium hydroxide activation of this mesoporous carbon results in a bimodal porous carbon with added microporosity of less than 2 nm to the existing mesopores without deterioration of the integrity of the original mesoporous carbon. Elemental sulfur has been loaded to the micropores through a solution infiltration method. The resulted S/C composites with various loading level of sulfur have a high surface areas and large internal porosities. These materials have been tested as novel cathodes for Li/S batteries. The results show that the cyclability and the utilization of sulfur in the Li/S batteries have been significantly improved. The large internal porosity and surface area of the micromesoporous carbon is essential for the high utilization of sulfur.

tremendous research efforts have been devoted to developing new electrolytes with expanded safety window [ 5,12 ] as well as modifying the surface of anodes [ 13 ] and cathodes [ 7,10,14 ] for improved stability, it is not easy to address the above four problems simultaneously. High-voltage lithium batteries can be successfully utilized only if all these problems associated with the cathode, the electrolyte, and the anode are solved fully.It is well known that many solid electrolytes have a voltage window beyond 5 V and thus do not decompose under anodic current, such as Li 10 GeP 2 S 12 , [ 15 ] Li 3 PS 4 , [ 16 ] Li 4 SnS 4 , [ 17 ] Li 7 La 3 Zr 2 O 12 , [ 18 ] and lithium phosphorus oxynitride (Lipon). [ 19 ] Furthermore, with a solid electrolyte, the concern of transition metal dissolution into the electrolyte is minimal. Compared with carbonate electrolytes, most ceramic solid electrolytes are intrinsically non-fl ammable. Lastly, lithium metal is compatible with many solid electrolytes and is less likely to form dendrites during cycling because of the mechanical robustness of the solid electrolyte. [ 20 ] The prominent problem of solid-state batteries is their low power densities compared with liquidelectrolyte lithium batteries, resulting from the low ionic conductivity of the solid electrolyte, the electrode/electrolyte interfacial compatibility, and limited kinetics of the electrodes. [ 21,22 ] The recently discovered solid electrolytes with high ionic conductivity enable the possibility of fabricating solid-state lithium batteries with a power performance comparable to that of liquid-electrolyte batteries. [ 15,23 ] On the other hand, interfacial instability between the electrode and electrolyte is a great challenge for solid-state batteries. [ 15,17,24,25 ] Proper engineering at the interfaces of electrode/electrolyte is required for good cycling performance of most solid-state lithium batteries. [ 15,24,26,27 ] Can solid-state batteries fundamentally tackle all the problems in high-voltage lithium batteries, the unstable cathodes, electrolytes, and anodes?In this work, we demonstrate the possibility to realize highvoltage cycling in solid-state systems using an example of LiNi 0.5 Mn 1.5 O 4 cathode, Lipon solid electrolyte, and Li metal anode. Disordered spinel phase LiNi 0.5 Mn 1.5 O 4 (theoretical capacity 147 mAh g −1 ) is one of the most attractive high-voltage cathodes because of its high operating voltage of ≈4.7 V, stable structure, and superior kinetics over ordered LiNi 0.5 Mn 1.5 O 4 . [ 2,28 ] Lipon is used as the model solid electrolyte mainly because of its wide voltage window (0-5.5 V) [ 19 ] and excellent interfacial compatibility with both cathodes and anodes. [ 19,29 ] Fabrication of thin-fi lm battery with LiNi 0.5 Mn 1.5 O 4 cathode has been challenging, [ 30 ] and this work demonstrates the fi rst successful application of LiNi 0.5 Mn 1.5 O 4 cathode in solid-state battery. Our results show that the solid-state high-voltage lithium battery delivers an outstanding cycling perfo...