No abstract

The open-shell p-electron compound Cs4O6 features anionic charge ordering with a concomitant jump in electronic conductivity.

Lithium silicon phosphorus oxynitride (LiSiPON) thin films with different compositions have been prepared by RF magnetron sputtering in N2 by using three targets xLi2SiO3 · (1 − x) Li3PO4 with x = 0.1, 0.3, and 0.5. Compared with LiPON, the electrical properties of LiSiPON have been improved by introducing silicon. LiSiPON films deposited from the target 0.5Li2SiO3 · 0.5Li3PO4 yield the highest ionic conductivity of up to 9.7 × 10−6 S cm−1 with an activation energy of only 0.41 eV. The main mechanism for increasing ionic conductivity is the enhancement of carrier mobility. By DC polarization measurements the electronic partial conductivity was found at least seven orders of magnitude smaller than the ionic conductivity. Linear voltammetry results showed that the LiSiPON films are electrochemically stable in contact with stainless steel in the voltage range of 0–6 V. The substitution of silicon for phosphorus in the film evidenced from X‐ray photoelectron spectroscopy analysis indicated silicon in the film will create more abundant cross‐linking structures Si–O–P and (P, Si)–N < (P, Si), hence created more Li+ conducting paths which favored the higher mobility of lithium ions and larger ionic conductivity. The optical bandgap was found to decrease with increasing silicon content. We demonstrate that the prepared LiSiPON films with their larger ionic conductivity and low electronic conductivity may serve as an alternative to LiPON for applications in high energy density and high voltage lithium batteries.

Most commercial lithium-ion batteries and other types of batteries rely on liquid electrolytes, which are preferred because of their high ionic conductivity, and facilitate fast charge-transfer kinetics at the electrodes. On the other hand, hybrid battery concepts that combine solid and liquid electrolytes might be needed to suppress unwanted shuttle effects in liquid electrolyte-only systems, in particular if mobile redox systems are involved in the cell chemistry. However, at the then newly introduced interface between liquid and solid electrolytes, a solid−liquid electrolyte interphase forms. In this study, we analyze the formation of such an interphase between the solid electrolyte lithium phosphorous oxide nitride (Li x PO y N z , "LiPON") and various liquid electrolytes using in situ neutron reflectometry, quartz crystal microbalance, and atomic force microscopy measurements. Our results show that the interphase consists of two layers: a nonconducting layer directly in contact with "LiPON" and a lithiumrich outer layer. Initially, a fast growth of the solid−liquid electrolyte interphase is observed, which slows down significantly afterward, resulting in a thickness of about 20 nm eventually. Here, a formation mechanism is proposed, which describes the solid−liquid electrolyte interphase growth as the fast deposition of a film, which mostly covers the "LiPON", with only a little degree of remaining porosity. The residual void space is then slowly filled, thus blocking the remaining channels for ionic conduction, which leads to increasing resistance of the interphase. The results obtained imply that hybrid battery concepts with liquid electrolyte and solid electrolyte can be hampered by highly resistive interphases, whose formation cannot be simply slowed down or suppressed. Further research is required regarding possible countermeasures.

to the high bulk conductivity and because LEs easily wet and fill the porous electrodes. These features enable fast bulk and interface kinetics of Li-ion exchange required for high rate capability. Otherwise, in any LE-based battery system, secondary reactions are taking place apart from the desired Li +-ion exchange that can be detrimental for cycle life and rate capability. This is especially the case if active material dissolves and diffuses from the cathode to the anode, creating a chemical short circuit or cross-talk, most particularly known as the polysulfide shuttle effect taking place in LE-based lithium-sulfur secondary batteries (LSSB). [1-7] Shuttle and active mass migration effects occur as well in LIBs [8] and redox catalyzed Li-O 2 cells. [9,10] Recent investigations prove that the migration of electrolyte decomposition products in high-voltage LIBs leads to strong capacity fading. [8] Main approaches to cure the parasitic shuttle shown forbut not limited to-LLSBs are as follows: 1) in situ established solid electrolyte interphase (SEI) formed via reaction of lithium and electrolyte compounds or additives (e.g., LiNO 3) [11] or 2) ex situ formed passivation layer (artificial SEI), using purely ion-conducting polymers [12] or inorganic coatings [13,14] are applied for anode protection. 3) The polysulfide diffusion out of the cathode is delayed by a cathode nanoscale architecture or sealing measures. [2,15-19] 4) "Solidification" of the Li-S 8 cell exclusively using polymers [20-23] or solid electrolytes [24,25] (SEs) circumvents the dissolution of polysulfides but suffers from slow transport kinetics of Li-ions inside solid lithium-ion conductors and across the interfaces. Especially the low rate capability of such systems limits their practical application as it is-beyond the energy density-the second crucial LIB property to enable energy storage for the electrification. Most recent approaches refer to hybrid cells (anode/LE a /SE/ LE c /cathode), comprising an LE in contact to the electrodes and an SE as a lithium-ion-selective barrier. The SE is separating anolyte (LE a) and catholyte (LE c) to suppress the chemical shortcircuit as well as to reduce the danger of dendrite growth and electronic short-circuit. [26-39] Hybrid cells can be tailored to 1) allow fast kinetics of the LE/porous electrode interfaces as well as 2) apply thin solid electrolyte membranes to limit the Li-ion path length through the solid phase with lower conductivity. Most electrochemical energy storages (battery cells) consist of solid electrodes separated by a liquid electrolyte. If electrode materials are-at least partially-soluble in the electrolyte, detrimental mass transport between both electrodes (electrode cross-talk) occurs. The shuttle mechanism in lithium-sulfur batteries and leaching of Mn in high voltage cathode materials are important examples. Implementing a solid electrolyte (SE) membrane between the electrodes is a comprehensible approach to suppress undesired mass transport but additional resistances arise d...