Synchronously Stabilizing the Interphase of Cathode and Anode Enabling Lithium Metal Batteries via Multiple Electrolyte Additives

Abstract

As the most promising high energy density technology, lithium metal batteries are associated with serious interfacial challenges because the electrolytes employed are unable to meet the requirements of both electrodes simultaneously, namely, the systems that work for Li metal are highly likely to be unsuitable for the cathode, and vice versa. In this study, we investigate the synergistic effects of lithium bis (oxalate) borate (LiBOB), fluoroethylene carbonate (FEC) and adiponitrile (ADN) to develop a formula that is compatible with both elements in the battery. The solid–electrolyte interphase (SEI) multi-layer generated from LiBOB and FEC successfully protects the electrolyte from the lithium and suppresses the decomposition of ADN on lithium, identified by the tiny amounts of isonitriles on the surface of the anode. Simultaneously, most of the ADN molecules remain and protect the cathode particles via the absorption layer of the nitrile groups, in the same way that this process works in commercial lithium-ion batteries. Benefiting from the stable interfacial films formed synchronously on the anode and cathode, the Li/LiNi0.8Co0.1Mn0.1O2 cells with an area capacity of ~3 mAh cm−2 operate stably beyond 250 cycles and target the accumulated capacity to levels as high as ~653.4 mAh cm−2. Our approach demonstrates that electrolyte engineering with known additives is a practical strategy for addressing the challenges of lithium batteries.

Keywords

• electrolyte additives
• forming SEI and CEI synchronously
• Li metal batteries