During the last decade, fuel cells have received enormous attention from research institutions and companies as novel electrical energy conversion systems. In the near future, they will see application in automotive propulsion, distributed power generation, and in low power portable devices (battery replacement). This review gives an introduction into the fundamentals and applications of fuel cells: Firstly, the environmental and social factors promoting fuel cell development are discussed, with an emphasis on the advantages of fuel cells compared to the conventional techniques. Then, the main reactions, which are responsible for the conversion of chemical into electrical energy in fuel cells, are given and the thermodynamic and kinetic fundamentals are stated. The theoretical and real efficiencies of fuel cells are also compared to that of internal combustion engines. Next, the different types of fuel cells and their main components are explained and the related material issues are presented. A section is devoted to fuel generation and storage, which is of paramount importance for the practical aspects of fuel cell use. Finally, attention is given to the integration of the fuel cells into complete systems.

Fuel Cells: Principles, Types, Fuels, and Applications

Recent advances in single-chamber solid oxide fuel cells: A review

Proton exchange membrane fuel cells

Design and fabrication of pumpless small direct methanol fuel cells for portable applications

Carbon-supported Pt–Fe alloy as a methanol-resistant oxygen-reduction catalyst for direct methanol fuel cells

Mixed-reactant, strip-cell direct methanol fuel cells

Chemical modification of electrode materials by heteroatom dopants is crucial for improving storage performance in rechargeable batteries. Electron configurations of different dopants significantly influence the chemical interactions inbetween and the chemical bonding with the host material, yet the mechanism underneath remains unclear. We revealed competitive doping chemistry of Group IIIA elements (boron and aluminum) taking nickel-rich cathode materials as a model. A notable difference between atomic radii of B and Al accounts for different spatial configurations of hybridized orbital in bonding with lattice oxygen. Density functional theory calculations reveal, Al is preferentially bonded to oxygen and vice versa, and shows much lower diffusion barrier than B(III). In case of Al-preoccupation, the bulk diffusion of B(III) is hindered. In this way, a B-rich surface and Al-rich bulk is formed, which helps to synergistically stabilize the structural evolution and surface chemistry of the cathode.

Competitive Doping Chemistry for Nickel-Rich Layered Oxide Cathode Materials.

The interfacial stability is highly responsible for the longevity and safety of sodium ion batteries (SIBs). However, the continuous solid-electrolyte interface (SEI) growth would deteriorate its stability. Essentially, the SEI growth is associated with the electron leakage behavior, yet few efforts have tried to suppress the SEI growth, from the perspective of mitigating electron leakage. Herein, we built two kinds of SEI layers with distinct growth behaviors, via the additive strategy. The SEI physicochemical features (morphology and componential information) and SEI electronic properties (LUMO level, band gap, electron work function) were investigated elaborately. Experimental and calculational analyses showed that, the SEI layer with suppressed growth delivers both the low electron driving force and the high electron insulation ability. Thus, the electron leakage is mitigated, which restrains the continuous SEI growth, and favors the interface stability with enhanced electrochemical performance.

Mitigating Electron Leakage of Solid Electrolyte Interface for Stable Sodium-Ion Batteries.

A feasibility analysis of a mixed-reactant, strip-cell direct methanol fuel cell concept is presented. In this type of cell, selective electrodes are mounted in an altemating fashion on the same side of a membrane electrolyte, which minimizes the need for ancillary equipment, and maximizes power density. At low current density, the fuel efficiency of the direct-methanol strip cell is shown to be higher than that of a bipolar cell with typical cathodes. The effect of geometric parameters on the performance of strip cells is discussed, and design recommendations are given for a simple geometry.

E. Wang

Papers

Mixed-reactant, strip-cell direct methanol fuel cells

Competitive Doping Chemistry for Nickel-Rich Layered Oxide Cathode Materials.

Mitigating Electron Leakage of Solid Electrolyte Interface for Stable Sodium-Ion Batteries.

Electrode performance and design for strip-cell direct methanol fuel cells