Concerns about thermal safety and unresolved highvoltage stability have impeded the commercialization of highenergy lithium-ion batteries bearing LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathodes. Enhancing the cathode structure and optimizing the electrolyte formula have demonstrated significant potential in improving the high-voltage properties of batteries while simultaneously minimizing thermal hazards. The current study reports the development of a high-voltage lithium-ion battery that is both safe and reliable, using single-crystal NCM811 and a dual-salt electrolyte (DSE). After 200 cycles at high voltage (up to 4.5 V), the capacity retention of the battery with DSE was 98.80%, while that for the battery with a traditional electrolyte was merely 86.14%. Additionally, in comparison to the traditional electrolyte, the DSE could raise the tipping temperature of a battery's thermal runaway (TR) by 31.1 °C and lower the maximum failure temperature by 76.1 °C. Moreover, the DSE could effectively reduce the battery's TR heat release rate (by 23.08%) as well as eliminate concerns relating to fire hazards (no fire during TR). Based on material characterization, the LiDFOB and LiBF 4 salts were found to facilitate the in situ formation of an F-and B-rich cathodeelectrolyte interphase, which aids in inhibiting oxygen and interfacial side reactions, thereby reducing the intensity of redox reactions within the battery. Therefore, the findings indicate that DSE is promising as a safe and high-voltage lithium-ion battery material.

The surface cooling technology of a power battery pack has led to undesired temperature gradient across the cell during thermal management and tab cooling has been proposed as a promising solution. This paper investigates the feasibility of applying tab cooling in large-format lithium-ion pouch cells using the cell cooling coefficient (CCC). A fundamental problem with tab cooling is that the CCC for tab cooling decreases as capacity increases. Coupling low CCCs with greater heat generation leads to significant temperature gradients across the cell. Here, the ‘bottleneck’ that limits heat rejection through the tabs is evaluated. The thermal resistance of the physical tabs is identified to be the main contributor towards the poor heat rejection pathway. A numerical thermal model is used to explore the effect of increased tab thickness and results showed that the cell-wide temperature gradients could be significantly reduced. At the negative tab, increasing from 0.2 to 2 mm led to a 100% increase in CCCneg while increasing the positive tab from 0.45 to 2 mm led to a 82% increasing in CCCpos. Together, this is shown to contribute to a 51% reduction in temperature gradient across the cell in any instance of operation.