Development/characterization of materials for electrochemical energy storage

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Public awareness of global climate change resulting from greenhouse gas emission has led to increasing utilization of renewable energy sources such as wind and solar, with further increases on the horizon. These sources are inherently intermittent in nature, necessitating effective methods of storing power for later use. High efficiency electrochemical energy storage (EES) devices are a key component to adopting these alternative energy sources. EES devices are the media used to store chemical energy that can be later converted back to electricity. Battery storage represents one way of providing storage, although energy could also be stored in the form of hydrogen through the electrolysis of water. EES device development and commercialization are limited by a number of materials engineering issues related to the fabrication, operation and long term reliability of these devices. The proposed research program will concentrate on the development and characterization of novel materials for EES applications, with an emphasis on two types of devices, zinc-ion batteries (ZIBs) and solid oxide electrolysis cells (SOECs). ******Solid oxide fuel cells (SOFCs) are devices that convert chemical energy into electrical energy. The typical fuel is hydrogen (although other fuels can be utilized) which is oxidized to water at the anode with electrons being released. An SOEC is essentially an SOFC operating in reverse. The two can be combined in a single device, referred to as a solid oxide cell (SOC). Typically, the hydrogen electrode is a cermet consisting of yttria stabilized zirconia (YSZ) and nickel (Ni). One of the issues limiting commercial application is long term stability of this electrode. The degradation mechanisms are not well understood, but are generally believed to be associated with Ni, i.e., Ni migration, Ni agglomeration and loss of Ni in the vapour phase. Studying the degradation mechanisms and proposing/implementing possible solutions is the focus of this part of the research project.******ZIBs are a promising candidate to store large amounts of electricity, since zinc is widely available and inexpensive. ZIBs use a high-capacity zinc (Zn) metal anode, metal oxide cathodes and aqueous electrolytes, with energy/power densities similar to lithium-ion batteries (LIBs). ZIBs offer advantages over LIBs, including improved safety, eco-friendliness and simpler manufacturing conditions. There are, however, drawbacks that restrict practical application of rechargeable ZIBs. These include poor efficiency, the formation of byproducts and rapid capacity fading due to the irreversible reactions associated with the metal oxide cathodes during battery cycling. The key to increasing efficiency and stability is to properly design new stable and high-capacity Zn-ion electrode materials. This work focuses on developing improved Zn-insertion cathodes to enable high energy densities over many cycles.