Magnesium-Ion Cathode Materials Based on the Barite Structure

Lithium-ion batteries have been a mainstay of the consumer electronics industries for nearly 25 years. Unlike many older energy storage systems, lithium-ion does not describe a specific chemistry but a family of chemistries and a mechanism of operation. As a result numerous types of materials are under the umbrella of lithium-ion batteries that can be modified and developed to meet a variety of end-user goals. Looking beyond-lithium ion, the landscape is less understood and explored. One promising area of Beyond-Lithium-Ion research has been magnesium-based systems. In this presentation we will explore the relationship between materials structure, electrolyte, and synthesis. Specific examples will be drawn from the multivalent work done by JCESR, an Energy Innovation Hub under the Department of Energy’s Office of Science. Insertion cathode materials including layered molybdates, vanadates, and related materials will be compared and contrasted to other potential host frameworks to assess limits in electrochemical performance that are driven by interfacial structure and electrolyte interactions1-5. Figure 1. Characterization of the as made Ca ion-exchanged NaxCoO2 samples with different calcium contents. The figure shows the normalized Ca XANES, indicated by solid lines, showing the sensitivity of this method to the concentration of calcium in the layered cobaltate. CaCO3 (orange, short dash) is included for comparison since Ca0.6CoO2 is expected to have CaCO3 impurities. Ca(PF6)2 (pink, long dash) is included to show that the discriminating features are well placed as compared to the CaxCoO2 spectrum. Each spectrum is offset by an additional -0.5 on the y axis, with the exception of CaCO3 and Ca(PF6)2. Composition was measured by EDS. (from ref 5). References Bucur, C.B., Gregory, T, A. G. Oliver, Muldoon, J., Phys. Chem. Lett. 6, 3578−3591 (2015). Amatucci, G., Badway, F., Singhal, A., Beaudoin, B., Skandan, G., Bowmer, T., Plitz, I., Pereira, N., Chapman, T., Jaworski, R., Journal of the Electrochemical Society, 148 A940-A950 (2001). Ling,C., Chen, J., Mizuno, F., Phys. Chem. C, 117, 21158−21165 (2013). Mohtadi, R., Mizuno, F., Beilstein J. Nanotechnol. 5 , 1291–1311(2014). Proffit, D. L., Fister, T.T., Kim, S., Pan, B., Liao, C., Vaughey J., Journal of the Electrochemical Society, 163 (13) A2508-A2514 (2016). Figure 1 <jats:p /

Designing New Magnesium-Based Cathode Materials

Lithium-ion batteries have been a mainstay of the consumer electronics industries for nearly 25 years. Unlike many older energy storage systems, lithium-ion does not describe a specific chemistry but a family of chemistries and a mechanism of operation. As a result numerous types of materials are under the umbrella of lithium-ion batteries that can be modified and developed to meet a variety of end-user goals. Looking beyond-lithium ion, the landscape is less understood and explored. One of our research efforts is to look at non-lithium cation based energy storage chemistries, including the MgxV2O5 and MgxV2O5*H2O systems. This talk will focus on recent developments from our lab in Mg-ion and Ca-ion chemistries with highlighting new types of cathodes, electrolytes, and anode materials1-5 References (1) Lipson, A.L; Han, S.-D; Kim, S. Pan, BF; Sa, N.; Liao; C, Fister, TT; Burrell, AK; Vaughey, JT; Ingram, BJ J. Power Sources 325 646-652 (2016). (2) Sa, N; Wang, H; Proffit, DL; Lipson, AL; Key, B; Liu, M; Feng, ZX; Fister, TT; Ren, Y; Sun, CJ; Vaughey, JT; Fenter, PA; Persson, KA; Burrell, AK J. Power Sources 323 44-50 (2016). (3) Sa, N; Kinnibrugh, TL; Wang, H; Gautam, GS; Chapman, KW; Vaughey, JT; Key, B; Fister, TT; Freeland, JW; Proffit, DL; Chupas, PJ; Ceder, G; Bareno, JG; Bloom, ID; Burrell, AK Chemistry of Materials, 28(9) 2962-2969 (2016). (4) Lipson, AL; Han, SD; Pan, B; See, KA; Gewirth, AA; Liao; Vaughey, J; Ingram, BJ J. Electrochem. Soc., 163(10) A2253-A2257 (2016). (5) Mukherjee, A.; Sa, N.; Phillips, P.; Burrell, AK; Vaughey, JT; Klie, R. Chemistry of Materials, 29, 2218−2226 (2017). Figure 1 <jats:p /

Electrolyte Development for Magnesium Ion Battery

Abundance of the magnesium element in the earth's crust as well as the safety features of Mg metal have attracted considerable attention for rechargeable Mg battery development. Before the successful invention of a prototype Mg ion battery, optimization of the Mg electrolyte performance is necessary. Exploration of the compatibility of an Mg electrolyte with high voltage cathode materials against Mg metal anode remains to be a big challenge. In this work, we will present some current studies of the electrolyte development for Mg ion battery. Specifically, electrochemical evaluation of the performance of the magnesium bis(trifluoromethane sulfonyl)imide-based non-aqueous electrolyte on the cathode and anode materials will be discussed.</jats:p

Progress Towards a Rechargeable Multivalent Battery

Cheaper batteries with higher capacity would increase the market penetration of electric vehicles and grid storage systems.  One way to achieve these gains in battery performance is to utilize a metal anode such as lithium, magnesium or calcium.  Lithium metal anodes have been extensively studied for decades, but still have not been commercialized.  On the other hand, comparatively little research has been performed on magnesium or calcium systems.  Magnesium metal has been shown to be less susceptible to the formation of dendrites than lithium.  No one is yet able to plate and strip calcium, however, it does possess a lower voltage than magnesium and a non-passivating oxide.  In order to rapidly explore the potential of these battery systems, we have developed techniques to study cathode materials without the need for a working metal anode.  In doing this we have determined that corrosion issues are more severe in these electrolytes than their lithium counterparts.  Furthermore, we have determined a class of materials that can intercalate Mg and Ca in nonaqueous electrolytes.  These materials are characterized by a combination of techniques including energy dispersive X-ray spectroscopy (EDX), X-ray absorption near-edge spectroscopy (XANES) and X-ray diffraction (XRD) to prove intercalation of the multivalent ion.  Additionally, we have made the first attempts to pair these materials with low voltage anode materials.  These anode materials include using Mg metal and metallic anodes that react with the multivalent ion.</jats:p

Reducing Side Reactions Using PF₆-based Electrolytes in Multivalent Hybrid Cells

ABSTRACTThe need for higher energy density batteries has spawned recent renewed interest in alternatives to lithium ion batteries, including multivalent chemistries that theoretically can provide twice the volumetric capacity if two electrons can be transferred per intercalating ion. Initial investigations of these chemistries have been limited to date by the lack of understanding of the compatibility between intercalation electrode materials, electrolytes, and current collectors. This work describes the utilization of hybrid cells to evaluate multivalent cathodes, consisting of high surface area carbon anodes and multivalent nonaqueous electrolytes that are compatible with oxide intercalation electrodes. In particular, electrolyte and current collector compatibility was investigated, and it was found that the carbon and active material play an important role in determining the compatibility of PF6-based multivalent electrolytes with carbon-based current collectors. Through the exploration of electrolytes that are compatible with the cathode, new cell chemistries and configurations can be developed, including a magnesium-ion battery with two intercalation host electrodes, which may expand the known Mg-based systems beyond the present state of the art sulfide-based cathodes with organohalide-magnesium based electrolytes.</jats:p

A Study of Mg Intercalation Mechanism of a Prospective Mg Full Cell Design

A preliminary prospective full cell design composed of V2O5·xH2O as cathode with a Mg metal as anode is constructed where insertion and de-insertion of magnesium into V2O5·xH2O is fully reversible. An in-depth understanding of the Mg intercalation mechanism is investigated by pair distribution function analysis, x-ray absorption near edge structure (XANES) and 25Mg magic angle spinning (MAS NMR) spectroscopy. Interestingly, Mg intercalation results in the formation of multiple phases with different interlayer spacings. Our findings showed that the interlayer spacing of V2O5·xH2O contracts upon Mg intercalation and expands for de-intercalation. An in-depth MAS NMR reveals the existence of two magnesium environments and more interestingly, magnesium intercalation induced a more well-defined Mg-O environment.</jats:p

²⁵mg NMR Studies of Mg-Ion Battery Materials

Multivalent-ion chemistries such as Mg-ion are emerging as alternative battery systems to Li-ion. Current Mg-ion chemistries are limited to relatively low voltages and relatively low reversible specific capacities (1-2). Recent research on potential high voltage Mg-ion cathode materials and alternative anode materials such as transition metal oxides and metal alloys have highlighted the urgent need to understand structure activity relationships and insertion/intercalation phenomenon for development of such systems (3). Solid state NMR is a powerful tool to investigate local structure and insertion/intercalation phenomena, particularly for batteries as shown for Li-ion chemistries with 6Li and 7Li NMR (4, 5). However, the low natural abundance (10%) of the NMR active Mg isotope (25Mg), highly quadrupolar nuclear spin of 25Mg (spin 5/2) and very low gyromagnetic ratio (i.e 30.6 MHz Larmor frequency relative to 1H = 500 MHz) limits the effective use of 25Mg NMR for solid Mg-ion battery materials (6). In this work, despite the challenges of 25Mg NMR, our recent efforts to characterize Mg environments in cathode materials such as MgMn2O4 spinels, MgV2O5, in anode materials such as h-TiO2 and Mg-Sn alloys will be presented. Chemical magnesiation using dibutylmagnesium and preliminary electrochemical (de)mangesiation and the structral changes induced will be discussed. The results will summarize the effectiveness of the method in distinguishing side reactions or undesirable conversion reactions, including amorphous phases, from intercalation phenomenon. References:           1.             D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H. Gizbar, R. Turgeman, Y. Cohen, M. Moshkovich, and E. Levi, Nature, 407 (6805), 724-727 (2000). 2.             H. D. Yoo, I. Shterenberg, Y. Gofer, G. Gershinsky, N. Pour, and D. Aurbach, Energ Environ Sci, 6 (8), 2265-2279 (2013). 3.             Magnesium Batteries 1 and 2, 224th Electrochemical Society Meeting, San Francisco CA, 2013 4.             C. P. Grey and N. Dupre, Chem. Rev. (Washington, DC, U. S.), 104, 4493 (2004). 5.             B. Key, R. Bhattacharyya, M. Morcrette, V. Seznec, J. M. Tarascon and C. P. Grey, Journal of the American Chemical Society, 131, 9239 (2009). 6.             R. Dupree and M. E. Smith, Journal of the Chemical Society-Chemical Communications, 1483 (1988).</jats:p

Cathode Materials for Rechargeable Mg and Ca Batteries

Batteries based on magnesium or calcium metal anodes have the potential to achieve energy densities exceeding current Li-ion batteries.  However, there are major challenges to overcome to make such a battery a reality.  One challenge is that currently no cathode materials have been identified that have sufficient energy density for a practical magnesium or calcium based battery.  Towards the end of finding higher energy density cathode materials, this poster presents two different materials approaches for the successful incorporation of Mg and Ca.  In particular, materials based on a Prussian blue type structure and with a polyanionic layered structure will be discussed.  Results presented include cycling performance, X-ray diffraction and X-ray based spectroscopies that prove intercalation of both Mg and Ca.  Comparing these classes of materials to others that have been shown to successfully intercalate Mg, yields insights into what makes a material a good candidate for future multivalent cathode research.  With these design principles guiding the search, a material that can achieve high energy densities for Mg or Ca chemistry can hopefully be found. </jats:p