Driving range and fast charge capability of electric vehicles are heavily dependent on the 3D microstructure of lithium-ion batteries (LiBs) and substantial fundamental research is required to optimise electrode design for specific operating conditions. Here we have developed a full microstructure-resolved 3D model using a novel X-ray nano-computed tomography (CT) dual-scan superimposition technique that captures features of the carbonbinder domain. This elucidates how LiB performance is markedly affected by microstructural heterogeneities, particularly under high rate conditions. The elongated shape and wide size distribution of the active particles not only affect the lithium-ion transport but also lead to a heterogeneous current distribution and non-uniform lithiation between particles and along the through-thickness direction. Building on these insights, we propose and compare potential graded-microstructure designs for next-generation battery electrodes. To guide manufacturing of electrode architectures, in-situ X-ray CT is shown to reliably reveal the porosity and tortuosity changes with incremental calendering steps.

We demonstrate the tailoring of highly oriented pyrolytic graphite (HOPG) to obtain uniformly sized islands of up to several microns in size. There has already been some research on manipulating individual sheets on HOPG surfaces with scanning probe microscope tips; such sheets were obtained either accidentally or with a less controllable indenting technique. Here we present a different approach, which is more reliable and controllable. The HOPG surface was first patterned to create an array of small graphite islands by reactive ion etching of the HOPG surface with an oxygen plasma. These islands were then manipulated with an atomic force microscope tip. Carbon nanotubes represent a promising material for nanotechnology and can be considered as a graphene sheet rolled into a seamless cylinder. While carbon nanotubes are synthesized successfully with laser ablation, carbon arc, or chemical vapour deposition techniques, we speculate that it might be possible, by the controlled fabrication of graphene sheets, to form nanotubes or other novel motifs of use for nanotechnology.

The principal inhibitor of fast charging lithium ion cells is the graphite negative electrode, where favorable conditions for lithium plating occur at high charge rates, causing accelerated degradation and safety...

devices to allow energy release at night and for continuous supply under low wind conditions. The most prevalent type of secondary energy storage uses lithiumion batteries (LIBs), that possess high energy density and long cycle life and have brought about a remarkable technical revolution for portable electronics, vehicles, and many other aspects in daily life. [1] However, considering the growing cost of the limited lithium resources and safety concerns derived from intrinsic chemical activity of metallic lithium and its combustible ester electrolytes, aqueous rechargeable batteries have been recently spotlighted as promising alternatives especially for utilization of large-scale energy storage stations. [2] Among them, aqueous zinc-ion batteries (AZIBs) have gained exceptional interest in aqueous systems due to the beneficial physicochemical properties of zinc, that is, i) a high theoretical volumetric capacity around 5585 mAh cm −3 of a metallic zinc anode compared with 2061 mAh cm −3 and 1129 mAh cm −3 for lithium and sodium anodes, respectively; ii) low redox potential of −0.762 V versus standard hydrogen electrode, and iii) electrochemical stability of metallic zinc in its sulfate solutions at near neutral or slightly acidic aqueous electrolyte providing the batteries with safe, costeffective, and environment-friendly characteristics. [3][4][5][6] Cost-effective and environmentally-friendly aqueous zinc-ion batteries (AZIBs) exhibit tremendous potential for application in grid-scale energy storage systems but are limited by suitable cathode materials. Hydrated vanadium bronzes have gained significant attention for AZIBs and can be produced with a range of different pre-intercalated ions, allowing their properties to be optimized. However, gaining a detailed understanding of the energy storage mechanisms within these cathode materials remains a great challenge due to their complex crystallographic frameworks, limiting rational design from the perspective of enhanced Zn 2+ diffusion over multiple length scales. Herein, a new class of hydrated porous δ-Ni 0.25 V 2 O 5 .nH 2 O nanoribbons for use as an AZIB cathode is reported. The cathode delivers reversibility showing 402 mAh g −1 at 0.2 A g −1 and a capacity retention of 98% over 1200 cycles at 5 A g −1 . A detailed investigation using experimental and computational approaches reveal that the host "δ" vanadate lattice has favorable Zn 2+ diffusion properties, arising from the atomic-level structure of the well-defined lattice channels. Furthermore, the microstructure of the as-prepared cathodes is examined using multi-length scale X-ray computed tomography for the first time in AZIBs and the effective diffusion coefficient is obtained by imagebased modeling, illustrating favorable porosity and satisfactory tortuosity.

Patterning of highly oriented pyrolytic graphite ͑HOPG͒ was demonstrated by oxygen plasma etching of lithographically patterned substrates. Periodic arrays of islands, or holes of several microns on an edge, were obtained on freshly cleaved HOPG surfaces which had been prepared with SiO 2 mask stops and then oxygen plasma etched. The etching process is described, including a study of etch rate as a function of rf power, and morphology was characterized with scanning electron microscopy.The graphite basal plane, also known as graphene, is a hexagonal network of sp 2 covalently bonded carbon atoms. 1 Graphite is very chemically stable in nonoxidizing environments, and is mechanically very stiff ͑the C 11 compliance constant is 1060 GPa͒, and these properties lead to its use in a variety of applications including in high-temperature, highstrength composites. 1 It is well established that the graphite basal plane is inert to chemical reaction with molecular oxygen, while it has limited resistance to atomic oxygen; at only 323 K, attack by atomic oxygen of graphite takes place readily. 2 Highly oriented pyrolytic graphite ͑HOPG͒ is a manmade material which is polycrystalline with highly oriented graphene sheets; the typical domain size in HOPG is 1-10 m in the basal plane and Ͼ0.1 m perpendicular to the basal plane. 3 We were motivated to pattern HOPG because of our interest in the mechanical strength of graphite in the basal plane, which has not been determined to date. Mechanical strengths as high as ϳ300 GPa for defect-free regions are theoretically predicted from local-density approximation calculations on a truncated graphene sheet, 4 and one might also expect from theoretical calculations on carbon nanotubes ͑which are graphene sheets wrapped into cylinders͒ that the graphene sheet strength will be remarkably high; 5 for comparison, the tensile strength of a high-grade tool steel oil quenched from 1143 K and single tempered at 478 K is 2.345 GPa. 6 One approach we have been recently developing for studying the mechanical properties of graphene is to pattern HOPG and then to manipulate the islands which are formed to obtain very thin sheets. We have reported on these studies separately. 7 Here, we report the creation of patterned islands and holes in HOPG, concentrating particularly on the lithographic patterning of appropriate mask stops and the oxygenplasma-etching method used.Beyond our interest in manipulating thin, lithographically prepared graphite islands, there are several other reasons to want to pattern HOPG. First, surface patterning may find application in developing ''graphene origami,'' a technique which may result in novel nanodevices by fabricating carbon by design. 7,8 Second, patterned HOPG surfaces can be used as special substrates for experiments in chemistry, biology, and medical research. Unique micrometer-or nanometer-sized containers can be created by etching small holes into HOPG substrates. As an example, Patrick, Cee, and Beebe studied the behavior of molecules on HOPG surface havin...

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Electrochemical and mechanical properties of lithium‐ion battery materials are heavily dependent on their 3D microstructure characteristics. A quantitative understanding of the role played by stochastic microstructures is critical for the prediction of material properties and for guiding synthesis processes. Furthermore, tailoring microstructure morphology is also a viable way of achieving optimal electrochemical and mechanical performances of lithium‐ion cells. To facilitate the establishment of microstructure‐resolved modeling and design methods, a review covering spatially and temporally resolved imaging of microstructure and electrochemical phenomena, microstructure statistical characterization and stochastic reconstruction, microstructure‐resolved modeling for property prediction, and machine learning for microstructure design is presented here. The perspectives on the unresolved challenges and opportunities in applying experimental data, modeling, and machine learning to improve the understanding of materials and identify paths toward enhanced performance of lithium‐ion cells are presented.

Fast discharge capability of automotive batteries not only affects the acceleration and climbing performance of electric vehicles, but also the accessible driving range under complex driving cycles. Understanding the intricate...