Ga-polymer dual interfacial layer modified Li metal for high-energy Li metal batteries

Lithium metal is regarded as the ultimate anode material for its extremely exceptional theoretical capacity and low reduction potential. Unfortunately, its practical utility has been constrained by changings such as the formation of lithium dendrites, volume expansion resulting from host-free structure, and uncontrollable side reactions with electrolyte. To achieve long cycle life, conventional single artificial layer strategy fails to solve due to ununiform lithium deposition problem. Consequently, the adoption of dual interfacial layer on lithium metal has emerged as prevailing strategy. In this study, we present a design of dual interface protective layer that combines a Ga-based liquid metal with the organic polymer Poly (ethylene glycol) diacrylate (PEGDA). This innovative combination offers synergistic benefits, including alleviate the volume effect and suppressing undesired interface side reactions. In practical test, the Li || Li symmetrical cell assembled from PEGDA Li-Ga dual interfacial layer maintains a low overpotential of 36.8 mV after 1400 h (2 mA cm−2, 2mAh cm−2). Moreover, even at a high rate of 5C, Li || LiNi0.8Co0.1Mn0.1O2 (NCM811, 1.0 mAh cm−2) cell still delivers a discharge capacity of 120 mAh g1, 1.4 times higher than bare Li. Notably, when integrated into a pouch cell with a LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode (1.52 mAh cm−2), this dual interface layers ensures stable performance over 60 cycles, with a capacity retention of 82 %. In summary, this innovative dual interface layer design offers a promising approach to address the intricate challenges associated with lithium metal protection and interface modification.