Layered LiCoO2–LiFeO2 Heterostructure Composite for Semiconductor-Based Fuel Cells

Abstract

Enabling fast ionic transport at a low-temperature range (400–600 °C) is of great importance to promoting the development of solid oxide fuel cells (SOFCs). In this study, a layer-structured LiCoO2–LiFeO2 heterostructure composite is explored for the low-temperature (LT) SOFCs. Fuel cell devices with different configurations are fabricated to investigate the multifunction property of LiCoO2–LiFeO2 heterostructure composites. The LiCoO2–LiFeO2 composite is employed as a cathode in conventional SOFCs and as a semiconductor membrane layer in semiconductor-based fuel cells (SBFCs). Enhanced ionic conductivity is realized by a composite of LiCoO2–LiFeO2 and Sm3+ doped ceria (SDC) electrolyte in SBFC. All these designed fuel cell devices display high open-circuit voltages (OCVs), along with promising cell performance. An improved power density of 714 mW cm−2 is achieved from the new SBFC device, compared to the conventional fuel cell configuration with LiCoO2–LiFeO2 as the cathode (162 mW cm−2 at 550 °C). These findings reveal promising multifunctional layered oxides for developing high-performance LT–SOFCs.

Remarkable Ionic Conductivity in a LZO-SDC Composite for Low-Temperature Solid Oxide Fuel Cells

“…With respect to the research and development of desirable electrolytes, recent studies have revealed that the use of BaCeO 3 and BaZrO 3 -based proton conductors, oxygendeficient semiconductors, composite materials, and the reduction of YSZ thickness by thin film techniques are feasible approaches, which result in modest decreases in the operating temperature of SOFCs down to 500-700 • C [6][7][8][9][10][11]. Particularly, semiconductor ionic materials and composite have been used to develop electrolytes to enable high ionic conductivity at low temperatures of 300-500 • C. These semiconductor electrolytes realize their electrolyte functionality via various semiconductor properties and conduction mechanisms, which are different from that of traditional electrolytes such as YSZ and Sm 0.2 Ce 0.8 O 1.9 (SDC) that primarily rely on cation substitution to create oxygen vacancies.…”

“…With respect to the research and development of desirable electrolytes, recent studies have revealed that the use of BaCeO 3 and BaZrO 3 -based proton conductors, oxygen-deficient semiconductors, composite materials, and the reduction of YSZ thickness by thin film techniques are feasible approaches, which result in modest decreases in the operating temperature of SOFCs down to 500–700 °C [ 6 , 7 , 8 , 9 , 10 , 11 ]. Particularly, semiconductor ionic materials and composite have been used to develop electrolytes to enable high ionic conductivity at low temperatures of 300–500 °C.…”

Systematic Analysis on the Effect of Sintering Temperature for Optimized Performance of Li0.15Ni0.45Zn0.4O2-Gd0.2Ce0.8O2-Li2CO3-Na2CO3-K2CO3 Based 3D Printed Single-Layer Ceramic Fuel Cell

“…Ionic conductors used in single-layer cells are mostly based on pure doped ceria, and composites of doped ceria and alkali carbonates. The electrode materials used in single-layer cells include LiCoO 2 -LiFeO 2 [ 10 ], Ni 0.8 Co 0.15 Al 0.05 LiO 2 [ 11 ], La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ [ 12 ], CuFe 2 O 4 [ 13 , 14 ], Li 0.15 Ni 0.25 Cu 0.1 Zn 0.2 Fe 0.3 O x [ 15 ], Li 0.3 Ni 0.6 Cu 0.07 Sr 0.03 O 2-δ [ 16 ], Sr 2 Fe 1.5 Mo 0.5 O 6-δ [ 17 ], Li 0.15 Ni 0.45 Zn 0.4 O 2 [ 18 ], etc. In addition, proton conductors (BaCe 0.7 Zr 0.1 Y 0.2 O 3-δ ) have been used in single-layer cells [ 19 ].…”

Self-Assembled Triple (H+/O2−/e−) Conducting Nanocomposite of Ba-Co-Ce-Y-O into an Electrolyte for Semiconductor Ionic Fuel Cells

“…Tremendous efforts have been dedicated to reduce the production cost and promote the performance of the cell based on functional materials and the revolutionary design of the structure of SOFCs [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. In recent years, SOFCs based on a ceramic proton conductor–also known as protonic ceramic fuel cells (PCFCs)–have demonstrated outstanding performance.…”

“…At the same time, the new architectures in heterostructure materials with a semiconductor and an ionic conductor yield interesting properties with ionic conduction highways between two-phase interfaces [ 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. A notable example is CeO 2 /CeO 2-δ core-shell structure, which exhibits a super proton conductivity of 0.16 S cm −1 for the electrolyte at 520 °C [ 11 ].…”