Research Progress of Anode-Free Lithium Metal Batteries

Lithium-metal batteries (LMBs) are regarded as the most promising candidate for practical applications in portable electronic devices and electric vehicles because of their high capacity and energy density. However, the uncontrollable growth of lithium dendrite reduces its cycling ability and even causes a severe safety concern, which impedes the development of the technology. Although great efforts have been devoted to solving the lithium dendrite issue in recent years, the contradiction between the high cost of thin Li foil and the severe safety hazard of excess Li still exists. This is precisely the factor that inspired the development of anode-free lithium-metal batteries (AFLMBs). Compared to lithium-metal batteries, AFLMBs with a zero-excess Li anode possess an incredible, conceivable, and specific energy. Additionally, because the use of metal lithium is limited, the battery manufacturing will be safer and simpler, leading to a significant decrease in cost. However, comprehensive reviews on anode-free batteries are rare. Therefore, in this review, we aim to explain the essential development factors influencing the cycle life, energy density, cost, and working mechanism of anode-free batteries. We summarize different strategies to improve the cycling stability of AFLMBs, and we discuss the application of anode-free electrodes in other electrochemical energy storage systems. Moreover, it is believed that the combination of modification techniques, including electrolytes and current collectors, and the application protocols will be the most important solution for future anode-free batteries.