ORALS

SESSION: BatteryFriPM1-R11	6th Intl. Symp. on Sustainable Secondary Battery Manufacturing and Recycling
Fri Oct, 25 2019 / Room: Coralino
Session Chairs: Guoran Li; Claudio Capiglia; Session Monitor: TBA

14:50: [BatteryFriPM107]
Adjustable Interlayer Spacing for Layered Titanate for Potassium Storage
Cheng-yen Lao¹ ; Vasant Kumar¹ ; Yingjun Liu¹ ; ¹University of Cambridge, Cambridge, United Kingdom;
Paper Id: 343 [Abstract]

Potassium-ion batteries (KIBs) are promising substitutes for lithium-ion batteries (LIBs) in grid-scale energy storage due to the Earth-abundancy of potassium [1]. Practical KIB applications, however, are hindered by slow diffusion kinetics and severe structural deterioration as the large cation is cycled in and out of the electrode, respectively leading to low specific capacity and short lifetime [2]. Herein we synthesize layered alkali titanates as electrode materials for KIBs by chemical reaction between nanoparticles and aqueous alkali hydroxides. By increasing the interlayer spacing of titanates, we show improvements in electrochemical performances in terms of specific capacity, charging rate and cycle life. Larger interlayer spacing allows quick and increased ion storage [3]. The adjustment of reaction temperature, concentration and types of hydroxides has direct effects on the interlayer spacing of these titanates. As a result, we have produced a range of alkali titanates with different interlayer spacing. Some as-prepared titanates with larger interlayer spacing deliver electrochemical performances for KIBs comparable to titanium-oxide based LIBs [4], [5]. Our work provides a method to design future energy storage electrode materials for large ions.

References:
[1] W. Zhang, Y. Liu, and Z. Guo, “Approaching high-performance potassium-ion batteries via advanced design strategies and engineering,” Sci. Adv., vol. 5, no. 5, p. eaav7412, May2019.
[2] T. A. Pham, K. E. Kweon, A. Samanta, V. Lordi, and J. E. Pask, “Solvation and dynamics of sodium and potassium in ethylene carbonate from ab Initio molecular dynamics simulations,” J. Phys. Chem. C, vol. 121, no. 40, pp. 21913–21920, Oct.2017.
[3] J. Yang et al., “Size-independent fast ion intercalation in two-dimensional titania nanosheets for alkali-metal-ion batteries,” Angew. Chemie Int. Ed., vol. 58, no. 26, pp. 8740–8745, Jun.2019.
[4] J. Liu, J. S. Chen, X. Wei, X. W. Lou, and X.-W. Liu, “Sandwich-like, stacked ultrathin titanate nanosheets for ultrafast lithium storage,” Adv. Mater., vol. 23, no. 8, pp. 998–1002, Dec.2010.
[5] J. Ma et al., “Layered lepidocrocite type structure isolated by revisiting the sol–gel chemistry of anatase TiO2: A new anode material for batteries,” Chem. Mater., vol. 29, no. 19, pp. 8313–8324, Oct.2017.

SESSION: BatteryFriPM2-R11	6th Intl. Symp. on Sustainable Secondary Battery Manufacturing and Recycling
Fri Oct, 25 2019 / Room: Coralino
Session Chairs: Katsuya Teshima; Deise Menezes Santos; Session Monitor: TBA

17:10: [BatteryFriPM212]
Graphene-based lithium-sulfur batteries
Liam Bird¹ ; Kai Xi¹ ; Cheng-yen Lao¹ ; Vasant Kumar¹ ; Andrea Ferrari¹ ; Caterina Ducati¹ ; ¹University of Cambridge, Cambridge, United Kingdom;
Paper Id: 453 [Abstract]

Lithium-sulfur (Li-S) batteries have a theoretical capacity of 1675 mAhg^-1[1], five times that of conventional Li-ion batteries[2], facilitated by the sulfur cathode undergoing a series of redox reactions to form lithium polysulfides (PS)[3]. However, the continuous diffusion of PS through the electrolyte results in progressive loss of electrical contact to the active material and hence poor capacity retention with repeated cycling[4, 5]. A lightweight, electrically conductive host framework compatible with scalable manufacture is therefore required to exploit sulfur’s low cost and abundance[6] in batteries with sustained high capacity. Templated mesoporous carbons, including CMK-3, are electronically conductive and have a hierarchical porous structure suitable for constraining PS[7]. However, graphene and related materials (GRMs) are compatible with higher throughput manufacturing processes[8]. In addition to high conductivity[8], mechanical strength[8], and surface area, GRMs offer opportunities for tunable functionalisation to increase PS binding energy to the host framework[9]. Here, we investigate the use of graphene nanoplatelets synthesised by microfluidization[10] (GNPs) and graphene oxide (GO) with CMK-3 as composite sulfur hosts for Li-S batteries. We find that a composite of GNPs and CMK-3 improves the capacity of Li-S batteries, and that a composite of GO and CMK-3 improves the capacity retention of batteries for the first ~100 cycles, compared to CMK-3 alone in identical conditions. The incorporation of GNPs appears to enhance the contribution of long-chain PS (Li2Sx for 4≤x≤8) to the cell’s capacity, demonstrating improved constraint of this active material in contact with the conducting host. This improves the cycling capability of Li-S batteries, facilitating their application in electric vehicles and grid-scale renewable energy storage.

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7 X. Ji, K. T. Lee, L. F. Nazar, Nat. Mater. 8, 500 (2009)
8 A. C. Ferrari, et al. Nanoscale, 11, 4598 (2015)
9 X. Zhou at al. J. Power Sources 243, 993 (2013)
10 P. G. Karagiannidis et al. ACS Nano 11, 2742 (2017)