Progress and Challenges for Energy-Dense and Cost-Effective Anode-Free Lithium Metal Batteries

Anode-free lithium metal batteries (AFLMBs), comprising a simple anode collector and a complete lithium cathode, are designed to minimize safety hazards associated with active Li metals, improve energy density, and simplify battery production. However, due to the irreversible loss of active lithium and the limited active lithium on the anode side, it generally leads to a rapid capacity loss of AFLMBs after only a few cycles. To enhance the extended cycling stability of AFLMBs, a thorough investigation spanning from battery components to design principles is required. In this paper, the main factors affecting the lifetime of AFLMBs, such as the induced nucleation relationship between the collector type and deposited Li, the determinative factors of Li deposition and stripping, and the interaction of mechanical and physicochemical properties of solid electrolyte interface (SEI) with the morphological evolution of various lithium deposits were studied. Subsequently, potential approaches and avenues to enhance the extended cycling performance of AFLMBs were deliberated and proposed, including electrolyte formulation adjustment to form SEI layers that promote uniform deposition of Li, cathode compensation for additional active lithium, and lipophilic coating or collection design with low nucleation barrier. And the important role of advanced testing techniques in guiding the development of AFLMBs was summarized. Finally, the further development of AFLMBs is discussed and proposed. The purpose of this review is to deepen the comprehension of AFLMBs and contribute to achieving an unprecedented cycle life in future.