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A layer-by-layer fabrication technique for a stacked on-chip supercapacitor operable in a wide range of temperatures (−20 °C to 70 °C) is demonstrated, and the prepared devices show competing performances at room and high temperatures.

Buffer reactions can prevent changes induced by external causes. Here, we demonstrate the significant buffer role of a very small amount of Mn in a self-optimized cathode for an aqueous Zn-ion battery. Our operando X-ray characterization studies reveal that the dissolution of most of the Mn in MnV2O4 during the first charging cycle induces atomic re-arrangement to form a disordered vanadium oxide phase with 0.88 at% Mn. Interestingly, the residual Mn ions exhibit voluntary migration between tetrahedral and octahedral sites during Zn2+ de/intercalation. This Mn migration not only stabilizes the main structure of the vanadium-based electrode, but also modulates the Fermi surface of V 3d against excessive drift. As result, the optimized cathode delivers an excellent capacity of 610.2 mA h g−1 at 0.2 A g−1 and long-term cycling stability over 4000 cycles. This buffer contribution via tunable metal ions exhibits high potential for applications in long-life metal-ion batteries and related fields.

The state-of-art Li-ion batteries have revolutionized the portable electronic industry and first-generation electric vehicles due to their high energy density at ambient temperatures. Owing to catastrophic failures under heat, these power devices are incompatible for applications such as in defence arsenals, subsurface drilling, space exploration and medical appliances, where performance at high-temperatures are as critical. Herein, we report an electrolyte formulation consists of Lithium bis(oxalato)borate (LiBOB) salt dissolved in propylene carbonate that enables lithium batteries to operate at extended temperature regime (>100 °C). The fundamental characterization of electrolyte system such as ionic conductivity, and internal resistance with respect to temperature promising for desired applications. Further, the electrolyte system is used to fabricate lithium batteries and the observed electrochemical results and lithium dendrites suppression capability confirmed its suitability for extended temperature applications without compromising ambient temperature performance.

Magnesium has gained a lot of attention due to its inherent properties such as light-weight with a density of 1.7 g/cm3 and the highest strength to weight ratio. Such unique properties make magnesium a suitable candidate for various applications including vehicles, aerospace projects, construction, energy storage applications and medical implants. One of the crucial issues with the use of magnesium on these applications is the tendency of the material to corrode. This is due to the high chemical activity of magnesium, its standard equilibrium potential of Mg/Mg2+ is -2.4 V vs. NHE. To prevent these problems, there have been reported strategies such as formation of alloys with noble metals or inert elements and the protection of the metal with a coating film.1 From the mentioned solutions, the most suitable solutions to prevent corrosion on magnesium without compromising its properties are the formation of alloys using passive elements such as Al, Ni or Cr and the protection of magnesium with a coating film. 2,3 Based on these two solutions, we propose to use aluminum as the second element for the alloy formation to prevent corrosion of magnesium and to enhance its structural, thermal, and electrical performance. In our study, we’ve been able to produce magnesium alloys by electro-co-deposition which have demonstrated to have a lower corrosion behavior compared to pristine magnesium films. Similarly, magnesium-based materials are gaining interest in energy storage application due to two-electron transfer per a reaction and thus a high volumetric capacity compared to the state-of-art Li-ion batteries. Also, they have shown to be safer than Li since Mg during cycling do not form dendrites.4 Herein, we explore the use of electro-co-deposited Mg-Al alloy as electrodes to construct high energy rechargeable Mg batteries. References (1) Esmaily, M.; Svensson, J. E.; Fajardo, S.; Birbilis, N.; Frankel, G. S.; Virtanen, S.; Arrabal, R.; Thomas, S.; Johansson, L. G. Fundamentals and Advances in Magnesium Alloy Corrosion. Prog. Mater. Sci. 2017, 89, 92–193. (2) Liu, R. L.; Scully, J. R.; Williams, G.; Birbilis, N. Reducing the Corrosion Rate of Magnesium via Microalloying Additions of Group 14 and 15 Elements. Electrochim. Acta 2018, 260, 184–195. (3) Yuwono, J. A.; Birbilis, N.; Liu, R.; Ou, Q.; Bao, Q.; Medhekar, N. V. Aqueous Electrochemical Activity of the Mg Surface: The Role of Group 14 and 15 Microalloying Elements. J. Electrochem. Soc. 2017, 164 (13), C918–C929. (4) Bucur, C. B. Challenges of a Rechargeable Magnesium Battery A Guide to the Viability of This Post Lithium-Ion Battery, 1st editio.; Spinger Briefs in Energy, 2018.

Recent advancements in an electrification of transportation sectors and adoption of renewable energies have increased a demand for energy storage devices with both high power density and energy density as current technologies including Li-ion battery (LIB) and electrical double layer capacitor (EDLC) can deliver either high energy or high power density. To bridge the gap between LIB and EDLC, Li-ion capacitors (LICs) was proposed by Amatucci in 2011[1] by employing a LIB-type electrode as an anode and a EDLC-type electrode as a cathode in carbonate based organic electrolytes containing Li-salts. Li-ions are stored in anode via intercalation process and anions are stored on cathode surface via adsorption. LIC is promised to combines the advantages of two entities by delivering high energy density, high power density, long cycle life, and low self-discharge.[2,3] However, the main challenge in LIC is the disparity in charge storage kinetics arising from the different charge storage mechanism in anode and cathode. To increase Li-ion kinetics in LIB-type electrode, many electrode-engineerings including nanostructuring active materials[4], making composites with carbonaceous nanomaterials[5–8], and utilizing electronically conductive sulfides[9] and nitrides[10] showed promising results. However, in spite of the considerable number of studies focusing on increasing power density of LIB-type electrode, only a few reports investigate the effects of electrolytes on the LIC performances.[11,12] The influences of anions in electrolytes on the LIC performance are indisputable as charge storage of the EDLC-type cathode sololy depends on the anion-adsorptions. Herein, this study explores the roles of different anions in Li-salts, including lithium hexfluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), and lithium bis(trifluoromethanesulfonyl)imide (LiC2F6NO4S2, LiTFSI), on the LIC performance. The prepared electrolytes were tested in a LIC consists of spinel lithium titanate anode (Li4Ti5O12, LTO) and activated carbon cathode (AC). The present study aims to highlight the important parameters to be considered when designing an optimized electrolyte system for LIC applications. [1] G.G. Amatucci, F. Badway, A. Du Pasquier, T. Zheng, J. Electrochem. Soc. 148 (2001) A930 [2] K. Naoi, S. Ishimoto, J. Miyamoto, W. Naoi, Energy Environ. Sci. 5 (2012) 9363 [3] W. Zuo, R. Li, C. Zhou, Y. Li, J. Xia, J. Liu, Adv. Sci. 4 (2017) 1 [4] L. Kong, C. Zhang, J. Wang, W. Qiao, L. Ling, D. Long, Sci. Rep. 6 (2016) 21177 [5] H. Kim, M.-Y. Cho, M.-H. Kim, K.-Y. Park, H. Gwon, Y. Lee, K.C. Roh, K. Kang, Adv. Energy Mater. 3 (2013) 1500 [6] J. Wang, H. Li, L. Shen, S. Dong, X. Zhang, RSC Adv. 6 (2016) 71338 [7] L. Yan, X. Rui, G. Chen, W. Xu, G. Zou, H. Luo, Nanoscale. 8 (2016) 8443 [8] Q. Wang, Z.H. Wen, J.H. Li, Adv. Funct. Mater. 16 (2006) 2141 [9] K. Kato, F.N. Sayed, G. Babu, P.M. Ajayan, 2D Mater. 5 (2018) 25016 [10] R. Wang, J. Lang, P. Zhang, Z. Lin, X. Yan, Adv. Adv. Funct. Mater. 25 (2015) 2270 [11] T. Zhang, B. Fuchs, M. Secchiaroli, M. Wohlfahrt-mehrens, S. Dsoke, Electrochim. Acta. 218 (2016) 163 [12] S. Liu, S. Liu, K. Huang, J. Liu, Y. Li, D. Fang, H. Wang, Y. Xia, J. Solid State Electrochem. 16 (2012) 1631

With the ever-imminent electrification of the transportation sector, the growth of renewable energy systems requiring better storage units, and the desire for smaller, faster, and smarter consumer electronics, the demand for Li-ion batteries (LIBs) to power the needs of the world is higher than ever. Over the past ten years, while battery prices have plummeted by a factor of four going from about $800/kWh to now $200/kWh for current chemistries1,2, costs of valuable metals within the batteries themselves have surged—notably in the most expensive part of the battery, the cathode, commonly made of cobalt-rich compounds. Cobalt in particular poses not only an economical burden, but a social and environmental one as well, instigating efforts to reduce the reliance on the conflict mineral while still maintaining high performance. Such efforts have led to the development of chemistries using other metals such as manganese and nickel, and has also pushed researchers to pursue more battery recycling options. In this work, a process to extract and reuse cobalt from LIBs containing lithium cobalt (III) oxide (LCO) has been developed using deep eutectic solvents (DESs), a “green” alternative to traditionally toxic solvents. DESs are solutions of two or more Lewis or Brønsted acids and bases that exhibit a deeply depressed freezing point; they can additionally made from cheap and potentially renewable materials3. Nickel metal was also tested in these eutectics, as the nickel manganese cobalt oxide (NMC) and lithium nickel cobalt aluminum oxide (NCA) batteries are projected to play a more prominent role in the future of Li-ion battery technology. The objective is to sustainably recycle these metals from LIBs and then repurpose it in other energy applications. In dissolution experiments simulating the extraction of cobalt from the traditional LIBs, LCO powder was mixed directly with the DES under heat, resulting in a vibrant aqua-blue solution indicating the presence of Co2+ ions. The solubilized metal was filtered and subsequently electrodeposited. Inductively coupled plasma optical emission spectrometry results showed record solubility values for a metal oxide in the presence of a DES. Similarly, experiments done using the nickel-based compounds showed promise for further development, leading to the eventual testing on spent Li-ion cathodes as well. Usage of the recovered metal in a supercapacitor and a new LIB cell demonstrates that such recycling can indeed apply sustainable means to a sustainable end—or rather a new beginning. References Opitz, A. et al., Can Li-Ion batteries be the panacea for automotive applications? Renewable and Sustainable Energy Reviews 2017, 68 (1), 685-692. “After electric cars, what more will it take for batteries to change the face of energy?” The Economist [London] 12 Aug. 2017. Electronic. Smith, E., et al. Deep Eutectic Solvents (DESs) and Their Applications. Rev. 2014, 114, 11060-11082.