Isocyanate Additives Improve the Low-Temperature Performance of LiNi_0.8Mn_0.1Co_0.1O₂||SiOx@Graphite Lithium-Ion Batteries

Abstract

LiNi0.8Mn0.1Co0.1O2||SiOx@graphite (NCM811||SiOx@G)-based lithium-ion batteries (LIBs) exhibit high energy density and have found wide applications in various fields, including electric vehicles. Nonetheless, its low-temperature performance remains a challenge. One of the most efficacious strategies to enhance the low-temperature functionality of battery is the development of appropriate electrolytes with low-temperature suitability. Herein, p-tolyl isocyanate (PTI) and 4-fluorophenyl isocyanate (4-FI) are used as additive substances to integrate into the electrolytes to improve the low-temperature performance of the battery. Theoretical calculations and experimental results indicate that PTI and 4-FI can both preferentially generate a stable SEI on the electrode surface, which is beneficial to reduce the interfacial impedance. As a result, the additive, i.e. 4-FI, is superior to PTI in improving the low-temperature performance of the battery due to the optimization of F in the SEI membrane components. At room temperature, the cyclic stability of the NCM811/SiOx@G pouch cell increases from 92.5% (without additive) to 94.2% (with 1% 4-FI) after 200 cycles at 0.5 C. Under the operating temperature of −20 °C, the cyclic stability of the NCM811/SiOx@G pouch cell increases from 83.2% (without additive) to 88.6% (with 1% 4-FI) after 100 cycles at 0.33 C. Therefore, a rational interphase design involving the modification of the additive structure is a cost-effective way to improve the performance of LIBs.

Co-Intercalation-Free Graphite Anode Enabled by an Additive Regulated Interphase in an Ether-Based Electrolyte for Low-Temperature Lithium-Ion Batteries

“…In comparison, LiN x O y originating from the decomposition of LiNO 3 is detected in the +10% FEC + 0.5 M LiNO 3 electrolyte (Figure d). The above results demonstrate that the joint addition of FEC and LiNO 3 contributes to the formation of intact SEI, in which the combination of LiF and LiN x O y enables good mechanical properties and fast ion conductivity . The XPS analyses are in accordance with the coordination structures.…”

Study on the electrical-thermal properties of lithium-ion battery materials in the NCM622/graphite system

“…Furthermore, we have observed that the presence of the electrolyte significantly reduces the thermal stability of both the positive and negative electrodes, lowering the temperature of heat generation and increasing the amount of heat released. Therefore, from the perspective of battery design, developing safer and more stable electrolytes (Han et al, 2023) or using solid-state electrolytes (J. Wang et al, 2023) are also important measures to prevent accidents.In summary, the exothermic reaction associated with the negative electrode exhibits significant heat generation over a long period, while the reaction associated with the positive electrode Experimental phenomena and temperature-voltage curve of cell heating test.…”

Electrolyte Design for NMC811||SiOx-Gr Lithium-Ion Batteries with Excellent Low-Temperature and High-Rate Performance

“…With standard EC-based electrolytes, NMC||SiO x -Gr cells cannot reach their full potential, especially under extreme conditions such as high-rate charging or low temperature operation. [24][25][26][27] The standard EC-based electrolytes exhibit low ionic conductivity and high viscosity, and they have a high desolvation energy barrier for lithium ions. 28,29 Consequently, during charging under extreme conditions, lithium ions tend to deposit on the anode surface rather than intercalating into the graphite or alloying with silicon.…”