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Lithium (Li) metal serving as an anode has the potential to double or triple stored energies in rechargeable Li batteries. However, they typically have short cycling lifetimes due to parasitic reactions between the Li metal and electrolyte. It is critically required to develop early fault-detection methods for different failure mechanisms and quick lifetime-prediction methods to ensure rapid development. Prior efforts to determine the dominant failure mechanisms have typically required destructive cell disassembly. In this study, non-destructive diagnostic method based on rest voltages and coulombic efficiency are used to easily distinguish the different failure mechanisms-from loss of Li inventory, electrolyte depletion, and increased cell impedance-which are deeply understood and well validated by experiments and modeling. Using this new diagnostic method, the maximum lifetime of a Li metal cell can be quickly predicted from tests of corresponding anode-free cells, which is important for the screenings of electrolytes, anode stabilization, optimization of operating conditions, and rational battery design.

Replacing precious metal catalysts by inexpensive activated carbon (AC) is a breakthrough in microbial fuel cell (MFC) cathode fabrication. In this study, AC powders made from bamboo, peat, coal, coconut, and hardwood sources are evaluated in terms of their electrochemical performance with carbon cloth as the base material. These ACs are characterized in terms of their conductivity, surface chemistry, surface area, and pore size distribution. The bamboo-based AC demonstrates the highest potential for use as a catalyst for carbon cloth based cathode, reaching 10.6 A m−2 at 0V vs. Ag/AgCl and a loading of 25 mg cm−2. The maximum power density reached 3.3 W m−2 in CEA–MFCs. The high performance of the bamboo-based AC cathode was possible due to the good conductivity and suitable surface chemistry of the bamboo AC and the high surface area of the base material. The hydrostatic pressure tolerance of the AC carbon cloth cathode is greater than 1.8 m, allowing for a more versatile cathode, suitable for use in many different reactor configurations.