Advanced Sulfur-Silicon Full Cell Architecture for Lithium Ion Batteries

With the advancements in portable electronics and electric vehicle (EV) applications, the demand for lithium-ion batteries (LIBs) with high energy densities is ever increasing. Battery-powered transportation is being adopted more frequently due to its potential to enable a more sustainable society by reducing vehicle emissions from fossil fuels. There has been exponential growth in the need for high-capacity LIBs in all types of EVs, including hybrid and full electric automobiles, e-bikes, and drones, as well as electric tools, cell phones, tablets, and, more recently, house storage; this growth significantly increases the consumption of source material commodities,especially cobalt. Despite its drop in price in the last couple of years due to increased mining, cobalt remains expensive, and its price increase has gained momentum again compared toother electrode materials due to higher demand. Moreover, its toxicity and difficult mining practices could result in many problems, including excessive carbon dioxide and nitrogendioxide emission along with a possible much higher demand in the long term. This provides a strong motivation to explore alternatives to battery source materials. In this article, we present a selection of our important works on LIBs, with a focus on alternative electrode chemistries by using abundant and sustainable material sources. As alternatives to traditional graphite-based anodes, we demonstrate the successful use of both silicon electrodes derived from beach sand and waste glass and carbon electrodes derived from portobello mushroom and waste plastic precursors. In addition, we demonstrate stable cycling of batteries with nonconventional electrode chemistries, such as lithium-sulfur with TiO2-coated sulfur electrodes and sulfur-silicon full cell batteries with integrated lithium sources. Batteries prepared by sustainable methods not only perform better than conventional ones but also result in reduced costs. Since accurate determination of battery state of health is another important challenge, we further present our electrochemical impedance spectroscopy-based analysis of LIBs, which could potentially be utilized in safety evaluations of current and next-generation LIBs.

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Multi-Functional Electrolyte for Thermal Management of Lithium-Ion Batteries

ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology ◽

10.1115/fuelcell2016-59460 ◽

2016 ◽

Author(s):

Kevin Westhoff ◽

Todd M. Bandhauer

Keyword(s):

Lithium Ion Batteries ◽

Thermal Management ◽

Boiling Point ◽

Volatile Component ◽

Lithium Ion ◽

Thermal Runaway ◽

Operating Conditions ◽

Onset Temperature ◽

Large Temperature ◽

Full Cell

The high thermal conduction resistances of lithium-ion batteries severely limits the effectiveness of conventional external thermal management systems. To remove heat from the insulated interior portions of the cell, a large temperature difference is required across the cell, and the center of the electrode stack can exceed the thermal runaway onset temperature even under normal cycling conditions. One potential solution is to remove heat locally inside the cell by evaporating a volatile component of the electrolyte. In this system, a high vapor pressure co-solvent evaporates at a low temperature prior to triggering thermal runaway. The vapor generated is transported to the skin of the cell, where it is condensed and transported back to the internal portion of the cell via surface tension forces. For this system to function, a co-solvent that has a boiling point below the thermal runaway onset temperature must also allow the cell to function under normal operating conditions. Low boiling point hydrofluoroethers (HFE) were first used by Arai to reduce LIB electrolyte flash points, and have been proven to be compatible with LIB chemistry. In the present study, HFE-7000 and ethyl methyl carbonate (EMC) 1:1 by volume are used to solvate 1.0 M LiTFSI to produce a candidate electrolyte for the proposed cooling system. Copper antimonide (Cu2Sb) and lithium iron phosphate (LiFePO4) are used in a full cell architecture with the candidate electrolyte in a custom electrolyte boiling facility. The facility enables direct viewing of the vapor generation within the full cell and characterizes the galvanostatic electrochemical performance. Test results show that the LFP/Cu2Sb cell is capable of operation even when a portion of the more volatile HFE-7000 is continuously evaporated.

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