Crystallite size effects can influence the performance of battery materials by making the structural chemistry deviate from what is predicted by the equilibrium phase diagram. The implications of this are profound: the properties of many battery materials should be reassessed. Sodium ion battery anodes made from nanocrystalline bismuth form different phases during electrochemical cycling compared to anodes with larger crystallites. This is due to the formation of a metastable cubic polymorph of Na 3 Bi on the crystallite surfaces. The structural differences (weaker Na−Bi bonds, different coordination of Na to Bi) between the metastable cubic Na 3 Bi phase found in the nanocrystals and the hexagonal equilibrium polymorph which dominates the larger crystallites offer an explanation for the improvements in cycling behavior observed for the nanostructured anode.

Lithium manganese oxide spinels are promising candidate materials for thin-film lithium-ion batteries owing to their high voltage, high specific capacity for storage of electrochemical energy, and minimal structural changes during battery operation. Atomic layer deposition (ALD) offers many benefits for preparing all-solidstate thin-film batteries, including excellent conformity and thickness control of the films. Yet, the number of available lithium-containing electrode materials obtained by ALD is limited. In this article, we demonstrate the ALD of lithium manganese oxide, Li x Mn 2 O 4 , from Mn(thd) 3 , Li(thd), and ozone. Films were polycrystalline in their asdeposited state and contained less than 0.5 at. % impurities. The chemical reactions between the lithium precursor and the film were found not to be purely surface-limited but to include a bulk component as well, contrary to what is usually found for ALD processes. In addition, we show a process for using Li(thd)/ozone and LiO t Bu/water treatments to transform ALD-MnO 2 and ALD-V 2 O 5 into Li x Mn 2 O 4 and Li x V 2 O 5 , respectively. The formed Li x Mn 2 O 4 films were characterized electrochemically and found to show high electrochemical capacities and high cycling stabilities.

The lithium ion battery concept is a promising energy storage system, both for larger automotive systems and smaller mobile devices. The smallest of these, the microbatteries, are commonly based on the all‐solid state concept consisting of thin layers of electroactive materials separated by a solid state electrolyte. The fact that solid state electrolytes are required puts rather severe constraints on the materials in terms of electronic and ionic conductivity, as well as lack of pinholes otherwise leading to self‐discharge. The atomic layer deposition (ALD) technology is especially suitable for realization of such microbatteries for the Li‐ion technology. ALD has an inherent nature to deposit conformal and pinhole free layers on complex geometrical shapes, an architecture most commonly adopted for microbattery designs. The current paper gives an overview of ALD‐type deposition processes of functional battery materials, including cathodes, electrolytes, and anodes with the aim of developing all‐solid‐state batteries. Deposition of Li‐containing materials by the ALD technique appears challenging and the status of current efforts is discussed.

Sodium-ion batteries may become an inexpensive alternative to lithium-ion batteries for large-scale stationary storage of energy generated by intermittent renewable sources. The key for the deployment of this technology is the development of suitable anode materials which can rival the graphite anodes used in lithium-ion batteries in terms of energy density, cycle life, rate performance, and safety. Here, we demonstrate that the bismuth metalates, BiVO4 and Bi2(MoO4)3, as representatives of ternary metalates, can cope with these requirements. High specific capacities (367 mAh/g and 352 mAh/g, respectively), exceptionally high cycling stability for alloying anodes (up to 79% of the first charge capacity is retained over 1000 cycles at ∼1C for Bi2(MoO4)3), better high-rate performance compared to other Bi-based anodes, low environmental load (Bi has low toxicity for a heavy metal), and low manufacturing costs (e.g., BiVO4 is a commercial yellow pigment) make this novel class of anode materials suitable for large-scale electrical energy storage applications. Operando XANES, ex situ XRD, and DFT analysis suggest that the initial compounds are converted into alloying Bi nanocrystallites confined in a matrix of electrochemically active insertion hosts Na3+x VO4 and Na2+x MoO4, respectively. The Bi metalate phases are not reformed on charge, and on subsequent cycles the reaction with Bi metal and vanadate/molybdate phases gives rise to the reversible capacity. The nanostructured composite anode thus obtained has excellent high rate performance and retains its capacity over hundreds of cycles.

LiAlO 2 thin films deposited by atomic layer deposition (ALD) have a potential application as an electrolyte in three-dimensional (3D) all-solid-state microbatteries. In this study, Li-ion conductivity of such films is investigated by both in-plane and cross-plane methods. LiAlO 2 thin films with a Li composition of [Li]/ ([Li] + [Al]) ¼ 0.46 and an amorphous structure were grown by ALD with thicknesses of 90, 160 and 235 nm on different substrates. The electrical characterization was conducted by impedance spectroscopy using inert electrodes over a temperature range of 25-200 C in an inert atmosphere. In-plane conductivities were obtained from films on insulating sapphire substrates, whereas cross-plane conductivities were measured from films on conducting titanium substrates. For the first time, comparison of the in-plane and cross-plane conductivities in these ALD LiAlO 2 films has been achieved.More comparable results are obtained using a cross-plane method, whereas in-plane conductivity measurements demonstrate a considerable thickness-dependence with thinner film thickness. The room-temperature conductivity of the LiAlO 2 films has been determined to be in the order of 10 À10 S cm À1 with an activation energy of ca. 0.8 eV. Fig. 1 Sketches of the (a) in-plane and (b) cross-plane geometrical configurations for thin film conductivity measurement. L: distance between the parallel band electrodes, l: length of band electrodes, d film : film thickness, A: electrode area. Red arrows indicate the current pathway. 60480 | RSC Adv., 2016, 6, 60479-60486 This journal is