Major breakthroughs in battery technologies are needed for electric vehicles that could safely drive longer on a single charge and recharge promptly. At the same time the deployment of wind and solar power for a sustainable economy requires powerful low-cost large-scale batteries with long cycle-life made from sustainable materials resources. It is obvious that the maturing Li-ion battery (LIB) technology relying on costly cathode materials, flammable electrolytes with limited electrochemical stability windows and bulky anodes with limited rate capabilities cannot offer the performance levels required for these key applications. In this talk, current R&D trends in overcoming these challenges will be outlined.

Back to the future - From Li-ion batteries to Li metal batteries: One of the most promising approaches to enhance the energy density and rate capability is to move back from LIBs to batteries that use metallic Li instead as the negative electrode. Replacing conventional graphite or oxide anodes with Li metal opens up a pathway to gravimetric energy densities up to 400 Wh/kg and volumetric energy densities approaching 1000 Wh/L. This approach had been abandoned a few decades ago due to the lack of electrolytes that at that time were known to be stable in contact with metal anodes and high voltage cathodes as well as the hazard of short-circuits by Li dendrites. Recent progress on solid electrolytes raises expectations that these could enable Li-metal batteries by acting as artificial anode protecting solid-electrolyte interfaces and mechanical barriers against dendrite growth.

Quidquid agis ... respice finem – focus on sustainable and scalable designs: For stationary large-scale applications where low cost and volumetric energy density gain importance, analogous strategies are pursued for Na-based batteries, which of course only makes sense if the low-cost high-performance anodes are combined with affordable, scalable cathodes, where high-cost transition metal compounds (e.g. Cobalt) are replaced by earth-abundant cathode materials.

Nihil nisi solidum - From liquid electrolytes to all-solid state batteries: While compatibility with current LIB fabrication may initially favour the replacement of anodes by Li-metal : anode-protecting membrane combinations, it appears natural to get rid of flammable liquid electrolytes altogether in order to enhance safety, (volumetric) energy density as well as reduce the need for enclosure of individual cells and enable longer cycle life systems. While data of individual solid electrolytes imply that this should be within reach, the key challenge remains to be the realisation of electrochemically stable electrolyte:electrode interfaces that ensure smooth charge transfer over a long cycle life despite the volume changes on cycling.

Getting the full picture - From materials design to system design: To overcome performance bottlenecks at system level it is widely recognised that the research focus has to shift from individual materials with record performance to a rational design of devices, which mainly involves the identification and engineering of favourable electrode:electrolyte combinations. Major progress can be expected in this area from combining the emerging experimental in situ and operando characterisation technologies with computational approaches.

Do What You Do Best: Moving from computer-aided to AI design: Analysing the wealth of complex experimental data e.g. from operando experiments or computational characterisations of a vast number of potential materials combinations and matching them to requirement profiles tailored for specific applications with an open mind for novel battery architec¬tures should be a fitting artificial intelligence problem. Thus, the most effective way to accelerate the develop¬ment of high performance energy storage systems may be to set up a dedicated battery design system and feed it with dependable standardised data, leaving the creative design to the AI tool. 

In this talk I will give a brief overview of the development of focused ion beam (FIB) systems starting with liquid metal ion sources to the current field emission sources. I will start with some of the early developments at Bell Labs where I worked on the development of a liquid metal ion source based focused ion beam systems and finding suitable applications for this technology. I will give examples of a number of material modification where the FIB systems could be of value.

The use of these ion beam systems can be classified largely in to materials modification, lithography and high resolution imaging. I would like to give some examples from the early work done at NUS on our first Helium ion microscope system and speculate on futuristic experiments.

The aberration-corrected scanning transmission electron microscope (STEM) provides real space imaging and spectroscopy with unprecedented sensitivity down to the single atom level. Thoroughly understanding and tailoring structural defects is extremely significant for understanding the structure-property relations of existing high-performance materials, and more importantly, guiding the design of new materials with improved properties. Several representative studies will be presented.

In 2D materials, sub-Ångstrom information transfer can be achieved at only 40 kV, and point defects and their local environments directly identified to correlate with properties. New edge structures in nanoporous MoS2 are found to exhibit excellent catalytic properties [1], and 2D Mo metal membranes can be fabricated from MoSe2 films via beam induced sputtering of Se [2].

In piezoelectrics, the development of lead-free materials with enhanced properties is urgently required. Precise mapping of atomic displacements reveals a hierarchical nanodomain structure as the origin of excellent properties, the coexistence of ferroelectric phases inside nanodomains and gradual polarization rotation between them [3,4]. Similarly, in thermoelectrics, a hierarchical structure ranging from point defects through nanoscale and microscale precipitates results in a high-performance material with lattice thermal conductivity approaching the theoretical minimum [5].

In oxide thin films, interplay of octahedral rotations, charge transfer and interdiffusion has major influence on carrier density and mobility and magnetic properties. Atomic resolution mapping of atomic displacements provides the most fundamental understanding of ferroelectric properties.

Finally, recent progress in optical sectioning to reveal the 3D structure of extended defects will be presented.

Reference:
[1] X. Zhao, et al., Nano Lett, 18 (2017) 482–490.
[2] X. Zhao, et al., Adv. Mater. (2018) 1707281.
[3] T. Zheng, et al., Energy Environ. Sci, 10 (2017) 528–537.
[4] B. Wu, et al., J Am Chem Soc, 138 (2016)15459–15464.
[5] Y. Xiao, et al., J Am Chem Soc, 139 (2017) 18732–18738.

The ORION NanoFab is an imaging, nanofabrication and characterization platform based on a high brightness and stable Gas Field Ion Source (GFIS). The GFIS employed exhibits a low energy spread, small virtual source size and a high brightness to produce fine probes of Helium and Neon ion beams. This, in conjunction with the shallow escape depth (<1 nm) of the secondary electrons generated by the incident ions, contribute to the high spatial resolution achievable with this technology. In addition to the high resolution, the integrated electron flood gun enables imaging of insulating samples without any conductive coating without charging artifacts. This has opened the application of this technology to a broad spectrum of multidisciplinary applications from basic materials science and semiconductor applications to the biological sciences.

Furthermore, the appreciable sputter yield from helium and neon ions and the small probe size enable material modification and nanopatterning capabilities at the sub-10 nm dimension. Direct milling and material modification with sub-10 nm features on graphene and other 2D materials, plasmonic devices on metals, nanopores and lithography of resists, direct metal and insulator deposition using gas injection systems have already been demonstrated with this tool.

The sputter process with the primary He or Ne ions results in secondary ions generated from the sample surface like in Secondary Ion Mass Spectroscopy (SIMS). By integrating a custom designed mass spectrometer to this platform, analytical and elemental characterization capabilities have been enabled to add-on to the existing capabilities of the tool. The ability to perform high sensitivity surface analysis and depth profiling with large dynamic range detecting all elements and differentiating isotopes with SIMS complements the surface sensitive imaging observed with this tool. We have demonstrated that our instrument is capable of producing elemental SIMS maps with lateral resolution down to 12 nm. Furthermore, the instruments opens up an in-situ correlative imaging technique combining high resolution SE images and SIMS elemental maps for various applications.

Electron Microscopy is a powerful imaging tool for analysis of composition, ultrastructure and function of biological samples and materials. From tissues and cells to subcellular structures and macromolecular complexes, Transmission and Scanning electron microscopy provides 2D and 3D morphological analysis. Studying and analysing structures in minute detail means we can learn more about how they function, leading to new insights into health and disease.

The presentation will describe several key examples from case studies to illustrate the use of Electron Microscopy. In microorganisms, morphological characterization provided valuable insights into Chikungunya virus of epidemic potential, Enterovirus 71 infection of the brain in Hand, foot and Mouth disease, the role of pili in streptococci, the localization of UL44 protein in HCMV infection. Working with cells, we can observe how Drosophilia cells use tunneling nanotubes for transport, how Shigella survives in Hela cells, Listeria monocytogenes in zebrafish and Chikungunya virus in Mosquitoes.
All are great examples of interactions between microorganisms and host cells and tissues.

Electron microscopy imaging has been used as a valuable research tool in the Life Sciences for many years. From research of single cell organisms, viruses or eukaryotic cells to identification of synaptic contacts between neurons, the ability to image biological samples in nanometer resolution has proven to be extremely valuable for many areas of biological research. The majority of these examples has been studied using the well-established Transmission Electron Microscopy (TEM) technique which requires thin sample preparations and limits the third dimension in scale and resolution.

Recent developments in Scanning Electron Microscopy (SEM) opens the spectrum of high resolution and high-volume imaging of biological tissue. Based on sample block-face scanning in combination with milling (e.g. Focused Ion Beam (FIB)) or block-face cutting techniques, SEM enables dramatic resolution improvements in the third dimension above what is possible with TEM. Furthermore, SEM offers large field of view imaging and opens up applications that have previously been unachievable in the lab.

In addition to the high volume and high-resolution imaging of SEM, FIB 3D SEM offers three-dimensional imaging of unstained cryo-frozen biological tissue opening the field for novel correlative studies using confocal microscopy. These include 3D colocalization of genetic markers and increase of context information for electron microscopy data.

Further correlative applications utilize X-Ray Microscopy (XRM) to non-destructively assess sample structure prior to subsequent analysis using electron microscopy. The correlation of datasets across length scale and imaging modality (light microscopy to XRM to electron microscopy) extends the portfolio of applications for research that has previously been unachievable in the lab. In addition, pre-scanning assessment of biological samples prior to 3D electron microscope techniques such as serial sectioning SEM or Focused Ion Beam SEM reduces experiment failure rate and experiment duration.

This talk will introduce some of the latest work in Life Science using 3D SEM techniques and discuss the future possibilities that imaging with this technology could provide.