Hybrid lithium-ion/lithium metal batteries (LIB/LMBs) are a promising solution to achieve higher energy density in lithium batteries by using a small amount of carbon anode (carbon anode/cathode < 1) for mixed storage of Li ions and Li metal. They reduce the anode cost of traditional LIBs and avoid the stringent environmental requirements during the fabrication of lithium metal batteries. However, under conditions such as high/low temperatures and fast charging, hybrid LIB/LMBs still suffer from poor Li reversibility and dendrite growth, leading to inferior battery stability.

Recently, the team led by Professor Zhifeng Zheng from our college has designed graphitized layer-encapsulated carbon nanofibers decorated with silver nanoparticles (G-CF-Ag) as the current collector/anode for LIB/LMBs, and tailored the interfacial chemistry to boost the performance of hybrid batteries. The graphitized outer layer effectively mitigates side reactions between the electrode and the electrolyte. The hard carbon structure inside the fibers ensures the battery's fast charging capability and low-potential storage performance. Silver nanoparticles enhance the lithiophilicity of carbon nanofibers and induce uniform Li deposition/stripping. The 1M LiFSI-THF-0.5wt.%LiNO₃ weakly solvating electrolyte modulates the interfacial chemistry, enabling rapid Li ion transport under fast charging and low-temperature conditions.

Consequently, under the hybrid storage mode (2.5–0 V, 500 mAh/g Li deposited below 0 V, ≈1.25 mAh/cm⟡ Li), the battery delivers an ultrahigh plateau capacity of 716 mAh/g (capacity below 0.1 V) at 0.2 C, and maintains an average Coulombic efficiency of 99.1% over 150 fast-charging cycles at 2 C. The battery operates stably even in a wide temperature range from 50°C to -20°C. Furthermore, with an N/P ratio of 0.3, the G-CF-Ag||NCM811 full cell achieves a high energy density of 587.5 Wh kg⁻¹ at 0.2 C. Under the same N/P ratio, the G-CF-Ag||LFP full cell can cycle stably across the wide temperature range of 50°C to -20°C.

This work has been published in the prestigious journal Advanced Functional Materials under the title "Interfacial Chemistry and Lithiophilicity Design for High Energy Hybrid Li-Ion/Metal Batteries in a Wide Temperature Range". Taiyu Lyu, a 2021-entry doctoral student of our college, is the first author. Professor Zhifeng Zheng from our college and Professor Lizhe Liang from Guangxi University are the co-corresponding authors. This research was supported by the Fujian Provincial Science and Technology Program (2022G02020, 2022H6002), the Platform Project of Fuzhou-Xiamen-Quanzhou National Independent Innovation Demonstration Zone (3502ZCQXT2022001), and the Xiamen Major Science and Technology Project (3502Z20231058).

Full paper link: https://doi.org/10.1002/adfm.202500212