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The substitution of an organic liquid electrolyte with lithium-conducting solid materials is a promising approach to overcome the limitations associated with conventional lithium-ion batteries. These constraints include a reduced electrochemical stability window, high toxicity, flammability, and the formation of lithium dendrites. In this way, all-solid-state batteries present themselves as ideal candidates for improving energy density, environmental friendliness, and safety. In particular, all-solid-state configurations allow the introduction of compact, lightweight, high-energy-density batteries, suitable for low-power applications, known as thin-film batteries. Moreover, solid electrolytes typically offer wide electrochemical stability windows, enabling the integration of high-voltage cathodes and permitting the fabrication of higher-energy-density batteries. A high-voltage, all-solid-state lithium-ion thin-film battery composed of LiNi0.5Mn1.5O4 cathode, a LiPON solid electrolyte, and a lithium metal anode has been deposited layer by layer on low-cost stainless-steel current collector substrates. The structural and electrochemical properties of each electroactive component of the battery had been analyzed separately prior to the full cell implementation. In addition to a study of the internal solid–solid interface, comparing them was done with two similar cells assembled using conventional lithium foil, one with thin-film solid electrolyte and another one with thin-film solid electrolyte plus a droplet of LP30 liquid electrolyte. The thin-film all-solid state cell developed in this work delivered 80.5 mAh g–1 in the first cycle at C/20 and after a C-rate test of 25 cycles at C/10, C/5, C/2, and 1C and stabilized its capacity at around 70 mAh g–1 for another 12 cycles prior to the start of its degradation. This cell reached gravimetric and volumetric energy densities of 333 Wh kg–1 and 1,212 Wh l–1, respectively. Overall, this cell showed a better performance than its counterparts assembled with Li foil, highlighting the importance of the battery interface control. The authors acknowledge the financial support from European H2020 project MONBASA (Monolithic Batteries for Spaceship Applications, grant no. 687561) and Basque Government through Elkartek 2017 program with the project Elkartek CICe2017-L4.

Lithium phosphorus oxynitride (LiPON) is an amorphous solid-state lithium ion conductor displaying exemplary cyclability against lithium metal anodes. There is no definitive explanation for this stability due to the limited understanding of the structure of LiPON. We provide a structural model of RF-sputtered LiPON via experimental and computational spectroscopic methods. Information about the short-range structure results from 1D and 2D solid-state nuclear magnetic resonance experiments investigating chemical shift anisotropy and dipolar interactions. These results are compared with first principles chemical shielding calculations of Li-P-O/N crystals and ab initio molecular dynamics-generated amorphous LiPON models to unequivocally identify the glassy structure as primarily isolated phosphate monomers with N incorporated in both apical and as bridging sites in phosphate dimers. Structural results suggest LiPON's stability is a result of its glassy character. Free-standing LiPON films are produced that exhibit a high degree of flexibility highlighting the unique mechanical properties of glassy materials.

The influence of nitrogen in the mechanism of ionic conduction has been studied in lithium phosphorus oxynitride glasses with composition xLi2O.(100 ¿ x)P2O5 (x = 38¿60 mol%). A correlation between glass structure and ionic conductivity has been established for explaining the conduction mechanism. The change of glass structure during nitridation has been studied as a function of lithium and nitrogen contents. Raman spectra confirm the increase of P2O74 ¿ groups with increasing lithium and the presence of nitrogen, as also shown by X-Ray Photoelectron Spectroscopy. The O1s core-level XPS spectra allow determining the variation of the bridging (BO) to non-bridging (NBO) oxygen ratio, observing that its decrease is directly linked to an increase of ionic conductivity. The ionic conductivity of oxynitride glasses is higher than that of their parent phosphate glasses, although this increase also depends on the lithium content. Furthermore, it has been demonstrated that the influence of nitrogen is higher in glasses with smaller amount of lithium. These findings will contribute to the design of glasses with lower lithium contents and high ionic conductivity for their application as solid electrolytes in lithium rechargeable batteries., Financial support from project MAT2010-20459 of Ministerio de Ciencia e Innovación is greatly acknowledged. N. Mascaraque thanks Ministerio de Economía y Competitividad for funding of a FPU-2009.

Microbatteries are energy sources well adapted to power various microsystems. To be considered as a microelectronic component, the latters must be compatible with the solder-reflow process which reaches a temperature of 260 °C during few seconds. In this study, we have investigated the effect of a solder-reflow type thermal treatment on the composition, local structure and electrical performances of the most used solid electrolyte, a lithium phosphorus oxynitride (LiPON). Amorphous thin films of LiPON were prepared by radio-frequency magnetron sputtering from a Li 3 PO 4 target with a pure nitrogen discharge gas. Ionic conductivity increases from 3.0 × 10 − 6 S cm − 1 to 7.2 × 10 − 6 S cm − 1 with the thermal treatment at 260 °C. However, this treatment induces an increase of the activation energy from 0.57 eV to 0.80 eV which is detrimental for a use of the microbattery at low temperature. The study of the local structure by X-ray photoelectron spectroscopy (XPS) shows the break of Li + … − O–P ionic bond and the formation of two new type of species such as Li 2 O and a Li–O–P environment with a covalent bond between lithium and oxygen atoms. This induces a decrease of the charge carrier mobility and so an increase of the activation energy. Nevertheless, as the ionic conductivity is improved, we can expect an increase of the mobile charge carrier density.

International audience; All-solid-state Li/LiPONB/TiOS microbatteries were manufactured at the pilot scale on silicon substrate. In a first attempt, the characterization of the active materials constituting the microbattery was achieved in order to determine their accurate composition, structure and morphology. Finally, a thorough electrochemical characterization was carried out on all-solid-state cells. Excellent performances were noted in terms of cycle life (with more than 1000 cycles), efficiency and self-discharge (less than 5% per year). In addition, the positive electrode highlighted a high volumetric capacity close to 90 μAh cm−2 μm−1 when cycled at 100 μA cm−2 between 1 V and 3 V vs. Li+/Li.

International audience; Amorphous thin solid films of lithium phosphorus oxynitride (LiPON) were prepared by radio-frequency sputtering from a Li3PO4 target by varying nitrogen flow rate. The aim of this study is to establish the correlations between deposition conditions, composition, local structure and the electrical properties of the electrolyte (ionic conductivity and activation energy). As expected, ionic conductivity of LiPON thin films increases with nitrogen flow rate reaching a maximum of 3.10−6 S cm−1 while the activation energy reaches a minimum of 0.57 eV. The use of three complementary techniques, X-ray photoelectron spectroscopy, Raman spectroscopy and Nuclear Magnetic Resonance has allowed a thorough investigation of the local structure of the LiPON thin films. The formation of phosphorus-nitrogen bonds in place of phosphorus-oxygen bonds involves two kinds of nitrogen atoms (N1: a nitrogen atom linked to two phosphorus atoms (-N=), and N2: a nitrogen atom linked to three phosphorus atoms (-N

The several materials required for fabrication of thin-film solid-state rechargeable lithium batteries were deposited and characterized: A glassy lithium-phosphorus oxynitride electrolyte (LiPON) between a lithium (Li) anode and crystalline lithium-cobalt oxide cathode (LiCoO2), deposited by RF-sputtering. Ti/Pt layers, deposited by e-beam were used in contacts and a silicon nitride film (Si3N4), deposited by low temperature hot-wire CVD protects the battery. This technology allows batteries with a potential of 4.5 V, typical capacities of 50 μAcm−2 and chargedischarge rates up to 4C. Solid-state film batteries show faster charge rates and very high cycle life, compared with film polymer batteries, withstanding several thousands of cycles with no pronounced fading., Portuguese Foundation for Science and Technology, project FCOMP-01-0124-FEDER-007226 (with the previous reference PTDC/EEA-ENE/66855/2006) and FCOMP- 01-0124-FEDER-010909 (with the previous reference FCT/PTDC/SAU-BEB/100392/2008).