Jin Zhu,Mingyu Zhang,Yunyan Gai,Ronghua Zeng,Yuepeng Cai,Dongsheng Lu
Tosylmethyl isocyanide (TosMIC) is used as electrolyte additive to study the effect on the cycling performance of LiNi 0.5 Mn 1.5 O 4 (LNMO)/graphite 5V lithium-ion cell. The constant current charge and discharge measurement results shows that the capacity retention rate of the cell containing 0.3 wt% TosMIC increases by 18% after 200 cycles, while 1.0 wt% TosMIC worsens the cycling performance of the cell. The decomposition product PF 5 of electrolyte salt LiPF 6 may interact with TosMIC to form TosMIC-PF 5 complex. The results of surface and electrochemical analysis indicate that the complex can be oxidized at the cathode and reduced at the anode simultaneously prior to the solvent molecules of the electrolyte. Theoretical calculation further shows that TosMIC-PF 5 can be oxidized to form a dimer (TosMIC-PF 5 ) 2 at 4.46V ( vs . Li/Li + ), which may be deposited on the LNMO cathode to help form a coating layer . This coating layer can be rapidly formed in the first cycle and can significantly alleviate the oxidation of the electrolyte, but it cannot inhibit the decomposition of excessive additive. Two proposed reduction reactions of TosMIC-PF 5 occur at 1.66 V and 2.00 V ( vs . Li/Li + ). Unfortunately, the reduction of this additive has a negative impact on the cycling performance of the cell.
Liu Yang,Kai Cui,Lu Chen,Yanxin Jiang,Hongji Pan,Chunlei Song,Junjie Chen,Anjun Hu,Tianshuai Wang,Jianping Long,Yiju Li
As a protic impurity, water can severely degrade battery life and pose safety risks. Lowering the H2O content in the electrolyte is essential, but it often requires energy-intensive drying technologies. Here, we develop a multifunctional interlayer utilizing dehydrated sepiolite on a commercial polypropylene separator (Sep@PP) to address water-induced challenges in lithium batteries. Its open channel and rich active sites (Si–O–Si, Mg–OH2, and Mg–OH groups) make it effectively absorb harmful impurities (e.g., H2O, HF, and transition metal ions), thereby preventing electrolyte decomposition, stabilizing the electrode interface, and further enhancing cycling stability. Moreover, the inherent thermal stability of dehydrated sepiolite endows the separator with exceptional heat resistance, mitigating thermal runaway risks and significantly enhancing overall battery safety. As a result, the LiNi0.5Mn1.5O4 (LNMO)//Li cell assembled with the Sep@PP separator exhibits excellent cycling stability, retaining 84.1% of its capacity over 500 cycles. Even when cycled in an electrolyte containing ultrahigh water content (1200 ppm), the LNMO//Li cell still maintains 81.7% of its capacity over 500 cycles, demonstrating its strong tolerance to moisture. Furthermore, the LiNi0.6Mn0.2Co0.2O2 (NCM622)//Li cell paired with the Sep@PP separator shows superior stability and maintains 72.3% of the initial capacity after 200 cycles, even at 55 °C. These findings underscore that leveraging the unique structure of dehydrated sepiolite presents a novel approach to mitigating water hazards in the modern battery industry.
危险品化学品经营许可证（带存储）