The overcharge safety performance of lithium-ion batteries has been the major bottleneck in the widespread deployment of this promising technology. Pushing the limitations further may jeopardize cell safety when it is performed at high-temperature storage. On the basis of the lacking systematic research on overcharge protection electrolyte additives with high-temperature storage capacity, we explore the promotion effect of overcharge additives on electrolyte decomposition at 60 °C. Specifically, the addition of tris(trimethylsily) phosphite (TMSP) and lithium difluoro(oxalato)borate (LiDFOB) in the electrolyte can not only form the robust cathode electrolyte interface/solid electrolyte interphase (CEI/SEI) but also improve the thermal stability of the electrolyte. Therefore, we promote the electrolyte system to realize the 18,650 LIB storage at 60 °C for 50 days by optimizing the formula in the electrolyte containing biphenyl (BP) and cyclohexylbenzene (CHB) overcharge protection additives, and the capacity retention rate can reach more than 90% with overcharge safety. Further, the optimized electrolyte system has also been implemented to commercial 18,650 LIBs and demonstrates the widening of the route to the widespread application of the electrolyte under extreme conditions.
Longjun Guo,Wei Liu,Xiaoliang Ji,Ying Zhong,Chunjin Hang,Chunqing Wang
In this work, a multiscale coralloid nano-Cu3Sn composed of a bimodal structure (∼55 and ∼120 nm) has been successfully synthesized to meet low-cost and Pb-free packaging demands for high-power electronic application. Owing to the excellent oxidation resistance of the Cu3Sn intermetallic compounds (IMCs) and the protection of solvent poly(ethylene glycol)-400 (PEG-400) at high temperature, the full-Cu3Sn joints sintered in air have a comparative shear strength with the joints acquired in vacuum when the sintering temperature is no more than 300 °C. The full-Cu3Sn joints acquired at 300 °C in air achieve a high bonding strength of 40.4 MPa, which is superior to those of traditional Sn-based solder joints (19 MPa) and full-Cu6Sn5 joints (17.7 MPa). The electrical resistivity of the sintered Cu3Sn films reaches 29.1 μΩ·cm in air. Cu3.02Sn0.98 is formed at the interface between the Cu substrate and sintered Cu3Sn layer, contributing to the exceptional bonding strength of the full-Cu3Sn joints. The bonding strength of the joints after high-temperature storage (HTS) tests reveals that the prepared full-Cu3Sn joints possess outstanding long-term thermal stability with a shear strength of 47.9 MPa after 800 h of storage at 250 °C. Our work breaks through the synthesis bottleneck of nano-Cu3Sn IMCs and provides the underlying insights needed to guide the design of highly stable full-IMC joints for high-temperature electronic packaging.
Sulfide solid-state electrolytes (SEs), prized for high ionic conductivity and mechanical strength, face practical challenges due to multi-field coupling failures under operational stresses. While prior studies emphasize electrochemical degradation (e.g., interfacial reactions, Li dendrites), thermal failure mechanisms during high-temperature storage remain overlooked. This work systematically explores calendar aging in sulfide-based all-solid-state batteries (ASSBs). Among tested systems, LiCoO₂ (LCO), Li 6 PS 5 Cl, and Li-In alloy exhibit superior stability after high-temperature storage. However, high-voltage LiNi 0.8 Co 0.1 Mn 0.1 O₂ (NCM811) undergoes structural collapse, releasing decomposition products that accelerate interfacial reactions and thermal failure. Batteries at high states of charge (SOC) experience intensified self-discharge-driven electrode-electrolyte reactions at elevated temperatures. In contrast, LCO-Li 6 PS 5 Cl-LiIn ASSBs at 0 SOC retain nearly undegraded performance after 5 days at 90°C. Suppressing the detrimental H3-phase transition in NCM811 improves capacity retention by ≥21%. The study elucidates high-temperature degradation pathways in sulfide ASSBs, linking thermo-electro-chemical coupling effects to interfacial ion transport barriers and contact degradation. These insights advance the understanding of calendar aging mechanisms, providing critical guidance for predicting battery lifespan and designing robust electrode/electrolyte systems.
危险品化学品经营许可证（带存储）