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A combinatorial library of twenty-three, phase pure, near-NMC111 (LiNi0·33Mn0·33Co0·33O2) compositions were synthesised and their electrochemical performance, was mapped (in lithium ion half-cells). Each of the 23 compositions was made in series, using a two-step process of 1) a rapid initial continuous hydrothermal precipitation, followed by 2) solid state lithiation. The 23 lithiated NMC samples were then subjected to analytical methods including electron microscopy (selected samples), Powder X-ray Diffraction and electrochemical tests in half cell Li-ion configurations versus Li metal. A sample with a Ni:Mn:Co (NMC) ratio of 39:28:33, revealed a specific capacity of 150 mA h g−1 at a C/20 rate, which was 63 and 43% greater capacity than NMC111 and NMC433 samples produced in this work, respectively. The sample with NMC ratio 47:25:28, showed the best capacity retention characteristics, retaining 70% of its C/20 capacity at 1C, after 40 cycles. Further analysis of all the samples by cyclic voltammetry and electrochemical impedance spectroscopy, allowed compositional mapping of diffusion coefficients. Overall, the mapping data revealed a gradual change of properties across compositional space, which has validated our combinatorial approach and allowed identification of the optimum performing near-NMC111 cathode materials.

Lithium‐ion batteries (LIBs) have been the focus of research for decades owing to their superior energy storage potential and wide range of applications. However, long‐term stability issues still persist in LIB cathodes as the result of the formation of a solid electrolyte interface (SEI), structural transformations, or the loss of active cathode materials. In nanoscale cathodes, it is often impossible to isolate, let alone mitigate the causes of the observed capacity loss. Herein, a novel approach is presented to synthesizing LIB cathode model systems using thin‐film molecular beam epitaxy (MBE). Specifically, 100 nm thick LiMn2O4 (LMO) thin‐film cathodes are grown on SrRuO3/SrTiO3 (100) single‐crystal substrates and characterized in their pristine and cycled states. The pristine thin films exhibit the electro‐chemical cycling behavior and structural evolution previously seen in bulk LMO cathodes. The formation of surface‐layer rocksalt MnO and spinel Mn3O4 along with the mass‐loss associated with the corrosion of active Mn ions is also reported. It is, therefore, demonstrated that these MBE‐grown model systems can be used for detailed studies of their surface structures and the electrode/electrolyte interfacial evolution in LIB cathodes, leading to the development of materials for rechargeable batteries with higher capacity and better stability. [ABSTRACT FROM AUTHOR]

Complex metal oxides (CMOs) are used broadly in applications including electroreactive forms found in lithium-ion battery technology. Computational chemistry can provide unique information about how the properties of CMO cathode materials change in response to changes in stoichiometry, for example, changes of the lithium (Li) content during the charge–discharge cycle of the battery. However, this is difficult to measure experimentally due to the small cross-sectional area of the cations. Outside of operational conditions, the Li content can influence the transformations of the CMO when exposed to the environment. For example, metal release from CMOs in aqueous settings has been identified as a cross-cutting mechanism important to CMO degradation. Computational studies investigating metal release from CMOs show that the thermodynamics depend on the oxidation states of lattice cations, which is expected to vary with the lithium content. In this work, computational studies track changes in metal release trends as a function of Li content in Lix(Ni1/3Mn1/3Co1/3)O2 (NMC). The resulting dataset is used to construct a random forest tree (RFT) machine learning (ML) model. A modeling challenge in delithiation studies is the large configurational space to sample. Through investigating multiple configurations at each lithium fraction, we find structural features associated with favorable energies to chemically guide the identification of relevant structures and adequately predict voltage values. [ABSTRACT FROM AUTHOR]

Summary: Carbon fabric is proposed as an alternative current collector for fabricating water‐processed LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes in order to prevent electrode corrosion problems from the use of conventional Al foil. The interlaced fiber bundles in carbon fabric feature plenty of voids and a large surface area to accommodate electrode materials without requiring an insulating binder. Further, the connected network structure of carbon fabric serves as a three‐dimensional pathway for electron transport. However, our experiments also reveal the necessity to adopt a conductive agent, although a very high content of it reduces the uniform distribution of cathode materials. When increasing the content of conductive agent from 3% to 15%, capacity retention of the corresponding NCM811 cell rises from 76% to 93% after charge/discharge at 0.5 C for 300 cycles. The causes of this increase are discussed. [ABSTRACT FROM AUTHOR]

Complex metal oxides (CMOs) are used broadly in applications including electroreactive forms found in lithium-ion battery technology. Computational chemistry can provide unique information about how the properties of CMO cathode materials change in response to changes in stoichiometry, for example, changes of the lithium (Li) content during the charge–discharge cycle of the battery. However, this is difficult to measure experimentally due to the small cross-sectional area of the cations. Outside of operational conditions, the Li content can influence the transformations of the CMO when exposed to the environment. For example, metal release from CMOs in aqueous settings has been identified as a cross-cutting mechanism important to CMO degradation. Computational studies investigating metal release from CMOs show that the thermodynamics depend on the oxidation states of lattice cations, which is expected to vary with the lithium content. In this work, computational studies track changes in metal release trends as a function of Li content in Lix(Ni1/3Mn1/3Co1/3)O2 (NMC). The resulting dataset is used to construct a random forest tree (RFT) machine learning (ML) model. A modeling challenge in delithiation studies is the large configurational space to sample. Through investigating multiple configurations at each lithium fraction, we find structural features associated with favorable energies to chemically guide the identification of relevant structures and adequately predict voltage values.

A facile approach for the synthesis of core–shell composites composed of a commercial sulfur core and a carbon nanopowder shell with different morphologies and sizes is proposed. When these composites are used to prepare a cathode for lithium−sulfur batteries, their fabricated electrode slurries show better dispersion homogeneity than that prepared through the conventional method of simply mixing sulfur and carbon nanopowders. Hence, the resulting cathodes fabricated by using these composites show superior electronic and ionic conductivity compared to that produced through the conventional method. Electrochemical assessment demonstrates that lithium−sulfur batteries fabricated by using the composites show reduced self‐discharge and improved capacity and maintained 100 % of the columbic efficiency. However, these improvements cannot be achieved if the sulfur crystal of the composite is considerably large, as this negatively affects the dispersion of the electrode constituents. [ABSTRACT FROM AUTHOR]

Cold Sintering Process (CSP) is a new emerging technique to consolidate ceramic particulates and ceramic-based composites at ultralow temperatures with assistance of pressures and transient aqueous phases. In consideration of the low-temperature advantage that bridges the sintering conditions of different types of materials (e.g. ceramics and polymers), it thus opens up a new route to integrate materials and devices, as well as to enable the fabrication of novel composites particularly with the ceramic material as matrix. In this communication, we demonstrated the feasibility of applying CSP to achieve dense LiFePO 4 -based cathode composites at an extraordinary low-temperature ~240 °C. The cold-sintered composite cathodes exhibited ~89% of its theoretical density. A half-cell was subsequently assembled, and a good electrochemical performance was manifested by a high volumetric capacity ~340 mAh/cm 3 and a gravimetric capacity ~158 mAh/g. Furthermore a good rate performance and capacity retention during cycling test at 0.2 C was observed on these composites. [ABSTRACT FROM AUTHOR]

The fabrication process of Li-ion battery electrodes plays a prominent role in the microstructure and corresponding cell performance. Here, a mesoscale particle dynamics simulation is developed to relate the manufacturing process of a cathode containing Toda NCM-523 active material to physical and structural properties of the dried film. Particle interactions are simulated with shifted-force Lennard-Jones and granular Hertzian functions. LAMMPS, a freely available particle simulator, is used to generate particle trajectories and resulting predicted properties. To make simulations of the full film thickness feasible, the carbon binder domain (CBD) is approximated with μm-scale particles, each representing about 1000 carbon black particles and associated binder. Metrics for model parameterization and validation are measured experimentally and include the following: slurry viscosity, elasticity of the dried film, shrinkage ratio during drying, volume fraction of phases, slurry and dried film densities, and microstructure cross sections. Simulation results are in substantial agreement with experiment, showing that the simulations reasonably reproduce the relevant physics of particle arrangement during fabrication. [ABSTRACT FROM AUTHOR]

Combinatorial synthesis has proven extremely effective in screening for new battery materials for Li-ion battery electrodes. Here, a study in the Li-Ni-Mn-Co-O system is presented, wherein samples with nearly 800 distinct compositions were prepared using a combinatorial and high-throughput method to screen for single-phase materials of high interest as next generation positive electrode materials. X-ray diffraction is used to determine the crystal structure of each sample. The Gibbs' pyramid representing the pseudoquaternary system was studied by making samples within three distinct pseudoternary planes defined at fractional cobalt metal contents of 10%, 20%, and 30% within the Li-Ni-Mn-Co-O system. Two large single-phase regions were observed in the system: the layered region (ordered rocksalt) and cubic spinel region; both of which are of interest for next-generation positive electrodes in lithium-ion batteries. These regions were each found to stretch over a wide range of compositions within the Li-Ni-Mn-Co-O pseudoquaternary system and had complex coexistence regions existing between them. The sample cooling rate was found to have a significant effect on the position of the phase boundaries of the single-phase regions. The results of this work are intended to guide further research by narrowing the composition ranges worthy of study and to illustrate the broad range of applications where solution-based combinatorial synthesis can have significant impact. [ABSTRACT FROM AUTHOR]