Flame-retardant properties of in situ sol-gel synthesized inorganic borosilicate/silicate polymer scaffold matrix comprising ionic liquid

Abstract

This paper focuses on the superiority of organic-inorganic hybrid ion-gel electrolytes for lithium-ion batteries (LiBs) over commercial electrolytes, such as 1 M LiPF₆ in 1:1 ethylene carbonate (EC): dimethyl carbonate (DMC) {1 M LiPF₆-EC: DMC}, in terms of their flame susceptibility. These ion-gel electrolytes possess ionic liquid monomers, which are confined within the borosilicate or silicate matrices that are ideal for non-flammability. Naked flame tests confirm that the organic-inorganic hybrid electrolytes are less susceptible to flames, and these electrolytes do not suffer from a major loss in terms of weight. In addition, the hybrids are self-extinguishable. Therefore, these hybrids are only oxidized when subjected to a flame unlike other commercial electrolytes used in lithium-ion batteries. Supplementary analyses using differential scanning calorimetric studies reveal that the hybrids are glassy until the temperature reaches more than 100°C. The current results are consistent with previously published data on the organic-inorganic hybrids.

Key words： inorganic polymeric borosilicate network; organic-inorganic hybrids; self-extinguishability; nonflammability; lithium batteries; flame-retardants

Acknowledgments

This work was supported by the MEXT scholarship of the Japanese Government. The authors wish to thank Prof. Vito Di Noto of the University of Padova, Italy for helping with the DSC measurements.

References

1 Tarascon J M, Armand M. Issues and challenges facing rechargeable lithium batteries. Nature, 2001, 414(6861): 359–367

PMID

2 Zaghib K, Charest P, Guerfi A, Shim J, Perrier M, Striebel K. Safe Li-ion polymer batteries for HEV applications. Journal of Power Sources, 2004, 134(1): 124–129

3 Armand M, Tarascon J M. Building better batteries. Nature, 2008, 451(7179): 652–657

PMID

4 Goodenough J B, Park K S. The Li-ion rechargeable battery: a perspective. Journal of the American Chemical Society, 2013, 135(4): 1167–1176

PMID

5 Li N, Song H, Cui H, Wang C. Sn@ graphene grown on vertically aligned graphene for high-capacity, high-rate, and long-life lithium storage. Nano Energy, 2014, 3: 102–112

6 Li N, Jin S, Liao Q, Cui H, Wang C X. Encapsulated within graphene shell silicon nanoparticles anchored on vertically aligned graphene trees as lithium ion battery anodes. Nano Energy, 2014, 5: 105–115

7 Li N, Song H, Cui H, Yang G, Wang C. Self-assembled growth of Sn@ CNTs on vertically aligned graphene for binder-free high Li-storage and excellent stability. Journal of Materials Chemistry A, 2014, 2(8): 2526–2537

8 Williard N, He W, Hendricks C, Pecht M. Lessons learned from the 787 Dreamliner issue on the lithium-ion battery reliability. Energies, 2013, 6(9): 4682–4695

9 Wang Q, Ping P, Zhao X, Chu G, Sun J, Chen C. Thermal runaway caused by fire and explosion of lithium-ion battery. Journal of Power Sources, 2012, 208: 210–224

10 Sloop S E, Pugh J K, Wang S, Kerr J B, Kinoshita K. Chemical reactivity of PF₅ and LiPF₆ in ethylene carbonate/dimethyl carbonate solutions. Electrochemical and Solid-State Letters, 2001, 4(4): A42–A44

11 Spotnitz R, Franklin J. Abuse behavior of high power, lithium-ion cells. Journal of Power Sources, 2003, 113(1): 81–100

12 Spotnitz R M, Weaver J, Yeduvaka G, Doughty D H, Roth E P. Simulation of abuse tolerance of lithium-ion battery packs. Journal of Power Sources, 2007, 163(2): 1080–1086

13 Kim G H, Pesaran A, Spotnitz R. A three-dimensional thermal abuse model for lithium-ion cells. Journal of Power Sources, 2007, 170(2): 476–489

14 Harris S J, Timmons A, Pitz W J. A combustion chemistry analysis of carbonate solvents used in Li-ion batteries. Journal of Power Sources, 2009, 193(2): 855–858

15 Lisbona D, Snee T. A review of hazards associated with primary lithium and lithium-ion batteries. Process Safety and Environmental Protection, 2011, 89(6): 434–442

16 Ota H, Kominato A, Chun W J, Yasukawa E, Kasuya S. Effect of cyclic phosphate additive in non-flammable electrolyte. Journal of Power Sources, 2003, 119–121: 393–398

17 Wang X, Yamada C, Naito H, Segami G, Kibe K. High concentration trimethyl phosphate-based non-flammable electrolytes with improved charge-discharge performance of a graphite anode for lithium-ion cells. Journal of the Electrochemical Society, 2006, 153(1): A135–A139

18 Wen J, Yu Y, Chen C. A review on lithium-ion batteries safety issues: existing problems and possible solutions. Materials Express, 2012, 2(3): 197–212

19 Martinelli A. Effects of a protic ionic liquid on the reaction pathway during non-aqueous sol-gel synthesis of silica: a Raman spectroscopic investigation. International Journal of Molecular Sciences, 2014, 15(4): 6488–6503

PMID

20 Matsumi N, Toyota Y, Joshi P, Puneet P, Vedarajan R, Takekawa T. Boric ester-type molten salt via dehydrocoupling reaction. International Journal of Molecular Sciences, 2014, 15(11): 21080–21089

PMID

21 Smaran K S, Vedarajan R, Matsumi N. Design of organic-inorganic hybrid ion-gel electrolytes composed of borosilicate and allylimidazolium type ionic liquids. International Journal of Hydrogen Energy, 2014, 39(6): 2936–2942

22 Hess S, Wohlfahrt-Mehrens M, Wachtler M. Flammability of Li-ion battery electrolytes: flash point and self-extinguishing time measurements. Journal of the Electrochemical Society, 2015, 162(2): A3084–A3097

23 Mizumo T, Marwanta E, Matsumi N, Ohno H. Allylimidazolium halides as novel room temperature ionic liquids. Chemistry Letters, 2004, 33(10): 1360–1361

24 Smaran K S, Joshi P, Vedarajan R, Matsumi N. Optimisation of potential boundaries with dynamic electrochemical impedance spectroscopy for an anodic half-cell based on organic–inorganic hybrid electrolytes. ChemElectroChem, 2015, 2(12): 1913–1916