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.

Lithium-ion batteries (LIBs) play a key role in grid-scale energy storage, making the development of LIBs with higher gravimetric energy density (GED) a necessity. Reducing the mass of the inactive collector component or even removing the collector altogether is important for improving energy density. This work proposes a 3D network electrode constructed based on the linear structure of carbon fiber (CF), which is directly used as an anode material without using a copper foil collector, and compared with the existing graphite anode material. The results show that CF has better rate performance, and the specific capacity of CF at high loading (1.3 mg/cm2) increases to a different degree along with the initial cycle. The comprehensive performance of the full battery assembled with CF electrode as the anode and LiFePO4 as the cathode shows that its overall energy density is higher than that of the graphite/LiFePO4 battery. The energy densities of CF/LiFePO4 and Graphite/LiFePO4 after 10 cycles at 0.1A/g current density were 198.7 Wh/kg and 132.7 Wh/kg, respectively. The energy density and power density of CF/LiFePO4 at other current densities are also greater than those of Graphite/LiFePO4.

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