The prevention of thermal runaway (TR) in lithium‐ion batteries is vital as the technology is pushed to its limit of power and energy delivery in applications such as electric vehicles. TR and the resulting fire and explosion have been responsible for several high‐profile accidents and product recalls over the past decade. Herein, the causes of TR are described and novel preventative methods are examined, approaching the problem from different angles by altering the internal structure of the battery to undergo thermal shutdown or developing the battery and thermal management systems so that they can detect and prevent TR. Ultimately, a variety of different technologies is needed to address the emerging market of highly specialized lithium‐ion batteries. Key innovations discussed include positive temperature coefficient (PTC) materials, self‐healing polymer electrolytes, and hybrid liquid–solid‐state electrolytes. Mist cooling achieves a highly uniform temperature inside the battery pack without the need for pumps to circulate a coolant. The development of battery management systems (BMSs) which model the internal temperature of the cell from real‐time data and prevent the cell reaching a critical temperature is an essential area for further research.

In order to decrease the global dependence on fossil fuels, high energy density, rechargeable batteries with high charge capacity are required for mobile applications and efficient utilization of intermittent sources of renewable energy. Metal-air batteries are promising due to their high theoretical energy density. In particular, the iron-air battery, with a maximum specific energy output of 764 W h kg⁻¹_Fe, represents a low cost possibility. This paper considers an iron-air battery with nanocomposite electrodes, which achieves an energy density of 453 W h kg⁻¹_Fe and a maximum charge capacity of 814 mA h g⁻¹_Fe when cycled at a current density of 10 mA cm⁻², with a cell voltage of 0.76 V. The cell was manufactured by 3D printing, allowing rapid modifications and improvements to be implemented before an optimized prototype can be manufactured using traditional computer numerical control machining.

For iron-air batteries, it has yet to be established which iron-containing material is the best candidate for producing iron electrodes. Galvanostatic charge-discharge cycling up to a potential of −0.55 V vs. Hg/HgO was carried out for at least 20 cycles on steel mesh-coated hot pressed iron electrodes. Five different iron active materials were tested: carbonyl iron, Fe₃O₄ (magnetite), Fe₂O₃ (hematite), FeOOH (goethite) and iron sulfide, resulting in five hot pressed electrodes. In addition, five hot pressed electrodes were prepared using the same iron active materials but with further processing by ball milling. The specific capacity and voltage of the electrodes is compared, where possible, with similar iron electrodes reported in the literature. This paper reports the maximum, mean value and standard deviation of the specific discharge capacity for each electrode; the highest mean discharge capacity was achieved with the ball milled Fe₃O₄ electrode with a value of 610 mA h g⁻¹_Fe. The shortest formation period was observed for the goethite iron electrode, which achieved a maximum discharge capacity after just 3 cycles with a standard deviation of only 9 mA h g⁻¹_Fe over 21 cycles.