Title : Development of Boron Nitride nanotube-based additives to improve ionic conductivity and thermal stability for high-performance Li-ion batteries
Electrolyte additives have been widely used to improve the long-term cycling performance of lithium-ion batteries (LIBs) by preventing electrolyte decomposition at the electrodes. Currently, various electrolyte additives are being researched, and among them, additives that improve high-temperature stability to prevent ignition of the battery are under development. However, while these electrolyte additives improve the safety of the battery, they can also degrade the performance of the electrolyte and increase costs due to the additional additives. Therefore, there is a need for a new type of functional electrolyte material that overcomes the main limitations of the existing carbonate-based electrolyte system and is compatible with various electrolyte/electrode materials.
In this study, we propose boron nitride nanotubes (BNNT) as a multifunctional electrolyte additive to improve the performance of conventional LIBs, demonstrating high lithium transference numbers (~0.68) and increased ionic conductivity by up to 30% (~0.87 mS/cm), thereby proving excellent cycle stability. When BNNT is dispersed in the electrolyte, the confinement effect of anions at defect sites is enhanced and Li+ is strongly coordinated with the solvent molecules. Also, the Lewis acid interaction between the anions/solvent and BNNT promotes the dissociation of Li+ and accelerates Li+ transport, resulting in a high Li+ transference number.
Remarkably, BNNT-based electrolytes achieved stable capacity performance under various temperature conditions (-10 to 60 °C). It indicates that the design of these electrolytes can solve the low performance of LIBs at low or high-temperature conditions. Furthermore, the BNNT electrolytes also show stable and enhanced electrochemical cycle performance for varied cathode (NCM622, LCO) and anode materials (graphite, lithium metal) emphasizing upon its compatibility for different secondary storage devices. Electrochemical tests of NCM622//graphite full cells exhibit the highest reversible capacities of 153 mAh/g at 1C, and excellent cyclic retention after 500 cycles at high 10C with a specific capacity of 71.5 mAh/g with a Coulombic efficiency of 99.6%. Overall, we suggest BNNT as an excellent electrolyte additive to conventional carbonate-based electrolytes and could bring multifunctional benefits to LIB.
Audience Take Away:
- The audience including researchers, engineers, and battery manufacturers can learn various types of electrolyte additives to optimize the performance of Li-Ion batteries. By incorporating these additives into battery designs, they can enhance ionic conductivity, leading to faster charging and discharging rates. Moreover, improved thermal stability can prevent overheating issues and enhance the safety of Li-Ion batteries, which is most important in various applications, including electric vehicles and portable electronics.
- The development of BNNT based electrolyte additives represents a novel approach to enhancing battery performance. BNNT has been explored as a protective coating to the separators to reduce the cell short circuit as well as enhance thermal stability and Li+ conductivity. However, by demonstrating the feasibility of applying BNNT as electrolyte additives, other faculty members can build upon their research by conducting further studies, exploring different variations of BNNT additives, or investigating their applicability in other energy storage systems.