The present invention relates to single chamber fuel cells and systems and methods associated with the same. Architectures and materials that allow for high performance, enhanced fuel utilization, mechanical robustness, and mechanical flexibility are described. In some embodiments, multiple fuel cell units are arranged in a single chamber and may be, in some cases, connected to each other (e.g., connected in series, connected in parallel, etc.). Each fuel cell unit can be defined as one or more anode(s), one or more cathode(s), and an electrolyte able to maintain electrical separation between the anode(s) and cathode(s). The multiple fuel cell units are arranged in stacks in some cases. In one set of embodiments, the stacks of fuel cell units can be shaped and/or arranged to enhance the mixing of fuel and oxidant, thus improving distribution of reactants in the reaction zone. For example, the stacks of fuel cells may be arranged as fins within the fuel cell chamber. In addition, the stacks of fuel cells may be porous in some instances. In addition, the stacks of fuel cell units may be arranged to enhance other fluid flow parameters (e.g., residence time, reactant distribution, etc.). In some cases, the enhanced fluid flow may lead to increased fuel utilization and system efficiency.