The use of metal hydrides in fuel cell applications

Complex Metal Hydrides for Hydrogen, Thermal and Electrochemical Energy Storage

“…An emerging research direction is that of CMHs as H 2 storage materials for stationary fuel cells (FCs) for clean power generation in seasonal storage, remote area and off-grid applications [261][262][263][264]. Unlike the closed-loop applications discussed in Section 4, this application utilizes an electrolyser to produce H 2 , which is stored (e.g., in a metal hydride) until the consumption of hydrogen by the fuel cell is required for electricity production.…”

“…Unlike the closed-loop applications discussed in Section 4, this application utilizes an electrolyser to produce H 2 , which is stored (e.g., in a metal hydride) until the consumption of hydrogen by the fuel cell is required for electricity production. Interest in the use of classic intermetallic hydrides for this role began in the 1990s [261,262] and an in-depth review of the principles and progress on the use of metal hydrides in fuel cell applications has recently been published [264]. Some of the advantages of energy storage based on a photo voltaic (PV)-electrolyser-H 2 storage-fuel cell configuration over a PV-Li ion battery system include:…”

“…Additionally, the organic electrolyte is hazardous in the presence of an oxidizing agent, which may result in runaway reactions and the battery catching fire or exploding [267]. The classic intermetallic hydrides first studied at near-ambient temperatures in combination with FCs have intrinsic safety due to their modest H 2 pressures and operating temperatures combined with the endothermic nature of the H 2 release process [264]. A more complicated scenario is presented by CMHs due to the fact that they are, in general, strong reducing agents, and many have the potential to be flammable or pyrophoric upon contact with air or water.…”

“…An additional benefit of thermally integrating CMHs with moderate-and high-temperature FCs is that, by consuming a significant fraction of the waste heat generated, the CMHs could actually improve the thermal control of high-temperature FC stacks [264].…”

“…The step changes that occur for the NaH and LiBH4 curves are a result of a phase change for either one of the reactants or products. This figure is based on that from reference [264]. Figure 5 shows that, in general, the classic intermetallic hydrides are suitable for use with lowand moderate-temperature FCs (i.e., ~250 °C and below), including LT-and HT-PEMFCs, AFCs and PAFCs.…”