Electrochemical Properties of Layered NaxNix 2Mn1 x 2O2 0.5 amp; 8201; amp; 8804; amp; 8201;x amp; 8201; amp; 8804; amp; 8201;1.1 with P3 Structure as Cathode for Sodium Ion Batteries

The Na properties of Ni and Mn containing layered oxides of the type Na x Ni x 2Mn1 amp; 8722;x 2O2 are explored between Na contents of 0.5 amp; 8804;x amp; 8804;1.1. Charge balance is maintained by adjusting the Ni Mn ratio. X ray diffraction and scanning electron microscopy are used to characterize the structure and morphology. The primary phase for all as synthesized materials is P3, especially at Na contents below x amp; 8201; amp; 8804; amp; 8201;0.8. Samples with a Na content of x amp; 8201; amp; 8805; amp; 8201;0.9 lead to the formation of Na and Ni secondary phases. The Na storage properties are studied in half cells with two different voltage windows between 1.5 4.0 amp; 8201;V and 2.2 4.5 amp; 8201;V vs Na Na . Ni and Mn redox are active between 1.5 and 4.0 amp; 8201;V accompanying three voltage plateaus at 3.7, 3.0, and 2.1 amp; 8201;V, respectively. An additional high voltage plateau gt;4.0 amp; 8201;V is observed when increasing the cutoff voltage to 4.5 amp; 8201;V. The initial Na content has a strong influence on the discharge capacity which ranges from 90 amp; 8201;mAh amp; 8201;g amp; 8722;1 x amp; 8201; amp; 8201;1.1 to 210 amp; 8201;mAh amp; 8201;g amp; 8722;1 x amp; 8201; amp; 8201;0.6 . C rate tests up to 2C and cycle life over 150 cycles are discussed. Overall, the composition Na0.6Ni0.3Mn0.7O2 shows the most favorable properties with respect to capacity retention, rate capability, and initial Coulomb efficienc

In Situ Operando Electrochemical Dilatometry as a Method to Distinguish Charge Storage Mechanisms and Metal Plating Processes for Sodium and Lithium Ions in Hard Carbon Battery Electrodes

In situ operando electrochemical dilatometry ECD provides information on the expansion shrinkage of an electrode during cell cycling. It is shown that the ECD signal can be used as descriptor to characterize the charge storage behavior of lithium and sodium ions in hard carbon electrodes. It is found that sodium storage in hard carbons occurs by a three step mecha nism, namely I insertion, II pore filling, and III plating. Step III can be seen from a sudden increase in electrode thickness for potentials below around 36 mV versus Na Na and is assigned to plating on the hard carbon surface. Interestingly, this last step is absent in the case of lithium which demon strates that the storage behavior between both alkali metals is different. The plating mechanism is also supported by reference experiments in which bulk plating is enforced. Bulk plating on hard carbon electrodes can be detected more easily for sodium compared to lithium. It is also found that the type of binder strongly influences the dilatometry results. A comparison between the binders sodium salt of carboxymethyl cellulose and poly vinylidene difluoride shows that the use of the former leads to notably smaller first electrode expansion as well as a higher initial Coulomb efficienc

Interface Engineered Atomic Layer Deposition of 3D Li4Ti5O12 for High Capacity Lithium Ion 3D Thin Film Batteries

Upcoming energy autonomous mm scale Internet of things devices require high energy and high power microbatteries. On chip 3D thin amp; 64257;lm batteries TFBs are the most promising option but lack high rate anode materials. Here, Li 4 Ti 5 O12 thin amp; 64257;lms fabricated by atomic layer deposition ALD are electrochemically evaluated on 3D substrates for the amp; 64257;rst time. The 3D Li 4 Ti 5 O12 reveals an excellent footprint capacity of 20.23 amp; 956;Ah cm amp; 8722;2 at 1 C. The outstanding high rate capability is demonstrated with 7.75 amp; 956;Ah cm amp; 8722;2 at 5 mA cm amp; 8722;2 250 C while preserving a remarkable capacity retention of 97.4 after 500 cycles. Planar amp; 64257;lms with various thicknesses exhibit electrochemical nanoscale e amp; 64256;ects and are tuned to maximize performance. The developed ALD process enables conformal high quality spinel 111 textured Li 4 Ti 5 O12 amp; 64257;lms on Si substrates with an area enhancement of 9. Interface engineering by employing ultrathin AlOx on the current collector facilitates a required crystallization time reduction which ensures high amp; 64257;lm and interface quality and prospective on chip integration. This work demonstrates that 3D Li4 Ti 5 O12 by ALD can be an attractive solution for the microelectronics compatible fabrication of scalable high energy and high power Li ion 3D TFB

A Practical Guide for Using Electrochemical Dilatometry as Operando Tool in Battery and Supercapacitor Research

Lithium ion batteries and related battery concepts show an expansion and shrinkage breathing of the electrodes during cell cycling. The dimensional changes of an individual electrode or a complete cell can be continuously measured by electrochemical dilatometry ECD . The obtained data provides information on the electrode cell reaction itself but can be also used to study side reactions or other relevant aspects, e.g., how the breathing is influenced by the electrode binder and porosity. The method spans over a wide measurement range and allows the determination of macroscopic as well as nanoscopic changes. It has also been applied to supercapacitors. The method has been developed already in the 1970s but recent advancements and the availability of commercial setups have led to an increasing interest in ECD. At the same time, there is no best practice on how to evaluate the data and several pitfalls exist that can complicate the comparison of literature data. This review highlights the recent development and future trends of ECD and its use in battery and supercapacitor research. A practical guide on how to evaluate the data is provided along with a discussion on various factors that influence the measurement result

Electrochemical Study of Prussian White Cathodes with Glymes Pathway to Graphite Based Sodium Ion Battery Full Cells

Prussian white PW cathodes exhibit extremely fast rate kinetics for sodium ion Na insertion de insertion at relatively high potentials. However, one of the major bottlenecks is to pair them with appropriate anode materials having similar rate kinetics. Herein, the combination of graphite anodes and several glyme based electrolytes as appropriate building blocks for PW cathodes to achieve high power density without compromising on energy density is reported. Low defect, Na rich PW is synthesized, and its electrochemical behavior is studied with conventional carbonate based electrolytes as well as with diglyme 2G , tetraglyme 4G and a 1 amp; 8201; amp; 8201;1 mixture of 2G and 4G. The stability of the electrolytes is also monitored via in amp; 8197;situ operando pressure cell measurements. Graphite amp; 8201; amp; 8201;electrolyte amp; 8201; amp; 8201;PW cells are then studied in both two and three electrode configurations. It was found that glymes are compatible with the graphite PW electrode pair and the resulting cells exhibit very good cyclability and rate capabilit

Setup Design and Data Evaluation for DEMS in Sodium Ion Batteries, Demonstrated on a Mn Rich Cathode Material

Differential electrochemical mass spectrometry DEMS is a powerful operando method for analyzing side reactions in batteries. We describe our DEMS setup highlighting the relevance for implementing a reference electrode. Although the method provides valuable information, the correct assignment of the DEMS signals to types of gases and quantifying the amounts released can be challenging. A frequent limitation is that gas concentrations are calculated from single m z ratios. This has the drawback of overlooking unexpected gases which can cause misinterpretation of the signal intensities, or even attributing to gases which are not actually formed. We present a multiple concentration determination MCD algorithm that uses the full MS spectra, which allows a more reliable determi nation of the gas release. We demonstrate this approach for Na ion half cells with P2 Na0.67Mn3 4Ni1 4O2 NaMNO as cathode active material CAM . Studying the gassing behavior for two electrolyte formulations 1 M NaPF6 in propylene carbonate PC and in diglyme 2G . Against the general belief that glymes lead to more gassing at high potentials, we find that gas evolution for PC electrolytes is larger compared to 2G electro lytes. Dimethyl ether is found to be a decomposition product of 2G. Pressure change measurements are used to independently validate the gas quantificatio

Atomic Layer Deposition of Textured Li4Ti5O12 A High Power and Long Cycle Life Anode for Lithium Ion Thin Film Batteries

The zero strain Li4Ti5O12 is an attractive anode material for 3D solid state thin film batteries TFB to power upcoming autonomous sensor systems. Herein, Li4Ti5O12 thin films fabricated by atomic layer deposition ALD are electrochemically evaluated for the first time. The developed ALD process with a growth per cycle of 0.6 cycle amp; 8722;1 at 300 C enables high quality and dense spinel films with superior adhesion after annealing. The short lithium ion diffusion pathways of the nanostructured 30 nm films result in excellent electrochemical properties. Planar films reveal 98 of the theoretical capacity with 588 mAh cm amp; 8722;3 at 1 C. Substrate dependent film texture is identified as a key tuning parameter for exceptional C rate performance. The highly parallel grains of a strong out of plane 111 texture allow capacities of 278 mAh cm amp; 8722;3 at extreme rates of 200 C. Outstanding cycle performance is demonstrated, resulting in 97.9 capacity retention of the initial 366 mAh cm amp; 8722;3 after 1000 cycles at 100 C. Compared to other deposition techniques, the superior performance of ALD Li4Ti5O12 is a breakthrough towards scalable high power 3D TFB

From lithium to sodium: Cell chemistry of room temperature sodium-air and sodium-sulfur batteries

Research devoted to room temperature lithium–sulfur (Li/S8) and lithium–oxygen (Li/O2) batteries has significantly increased over the past ten years. The race to develop such cell systems is mainly motivated by the very high theoretical energy density and the abundance of sulfur and oxygen. The cell chemistry, however, is complex, and progress toward practical device development remains hampered by some fundamental key issues, which are currently being tackled by numerous approaches. Quite surprisingly, not much is known about the analogous sodium-based battery systems, although the already commercialized, high-temperature Na/S8 and Na/NiCl2 batteries suggest that a rechargeable battery based on sodium is feasible on a large scale. Moreover, the natural abundance of sodium is an attractive benefit for the development of batteries based on low cost components. This review provides a summary of the state-of-the-art knowledge on lithium–sulfur and lithium–oxygen batteries and a direct comparison with the analogous sodium systems. The general properties, major benefits and challenges, recent strategies for performance improvements and general guidelines for further development are summarized and critically discussed. In general, the substitution of lithium for sodium has a strong impact on the overall properties of the cell reaction and differences in ion transport, phase stability, electrode potential, energy density, etc. can be thus expected. Whether these differences will benefit a more reversible cell chemistry is still an open question, but some of the first reports on room temperature Na/S8 and Na/O2 cells already show some exciting differences as compared to the established Li/S8 and Li/O2 systems