Jacob R. Jokisaari

As a Postdoc in the Nanoscale Physics Group, Jake is a characterization expert.  Current work includes abberation corrected STEM/EELS of materials for multivalent and Li-ion batteries, and understanding liquids at nanoscale resolution using graphene-based in situ liquid cells.

Mohammad Asadi , Baharak Sayahpour, Pedram Abbasi , Anh T. Ngo, Klas Karis, Jacob R. Jokisaari, Cong Liu, Badri Narayanan, Marc Gerard , Poya Yasaei , Xuan Hu, Arijita Mukherjee, Kah Chun Lau, Rajeev S. Assary, Fatemeh Khalili-Araghi, Robert F. Klie, Larry A. Curtiss & Amin Salehi-Khojin, A lithium–oxygen battery with a long cycle life in an air-like atmosphere, Nature, Vol. 555, 502 (2018)

Xuan Hu, Poya Yasaei, Jacob R. Jokisaari, Serdar Öğüt, Amin Salehi-Khojin, Robert Klie,Nanoscale Mapping Thermal Expansion Coefficients in Freestanding 2D Materials

at the Nanometer Scale,  Phys. Rev. Lett. 120, 055902 (2018)

Hyun Deog Yoo, Jacob R. Jokisaari, Young-Sang Yu, Mario Lopez, Saul H. Lapidus, Soojeong Kim, Gene M. Nolis, Sang-Don Han, Brian J. Ingram, Igor Bolotin, Linhua Hu, Shabbir Ahmed, Robert F. Klie, John T. Vaughey, Tim T. Fister, Jordi Cabana, Intercalation of Magnesium into a Layered Vanadium Oxide with High Capacity, Nat. Chem. (submitted), May (2018)

Jacob R. Jokisaari, Jordan A. Hachtel, Xuan Hu, Arijita Mukherjee, Canhui Wang,

Andrea Konecna, Tracy C. Lovejoy, Niklas Dellby, Javier Aizpurua, Ondrej L. Krivanek,

Juan-Carlos Idrobo, and Robert F. Klie, Vibrational spectroscopy of water with high spatial resolution, Advanced Materials (under review), June (2018)

Energy storage has been identified as a major bottleneck in transportation, energy production, and electronic device technologies.  In particular, all of these utilize rechargable batteries, where an ion such as Li or Mg travels from the anode end to the cathode end during discharge. Design of appropriate hosts for the Li, Mg, or other ions necessitates observing the atomic-scale processes involved in intercalating the ion into the material. Intercalation of the ion both reversibly and irreversibly alters the host. Understanding these processes is fundamental to the design of new high-capacity, high-rate batteries for the next generation of technology. Abberation-corrected scanning transmission electron microscopy (STEM) provides atomic resolution imaging, coupled with chemically sensitive electron energy loss  (EELS) and energy dispersive x-ray (EDS) spectroscopies, and lends direct insight into the physical mechanisms controlling charging and discharging processes.

Meanwhile, liquids and liquid interfaces play a significant role in many, many processes, yet understanding nanoscale interactions in liquid environments has proved exceptionally difficult. Recent advances in electron microscopy have allowed the construction of silicon chip-based encapsulated liquid environments allowing imaging and in situ probing at resolutions approaching single-nanometer.  However, to make full use of the atomic-scale spatial resolution, as well as EELS and EDS analysis, thinner window materials encapsulating smaller liquid droplets are required. Utilizing graphene or other 2D materials , 35-50 nm thick liquid cell samples  containing a large variety of samples from organics to nanoparticles can be realized, and the interaction between liquid and sample probed at resolutions approaching the atomic scale.  Leveraging the most modern monochromated electron sources, it is even possible to conduct vibrational spectroscopy at  better than 10 nm spatial resolution. A schematic example is shown in the figure. This new window to the nanoscale has immense potential for a wide range of scientific disciplines.