Research Progress of Anode-Free Lithium Metal Batteries

Abstract

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.

A review on “Growth mechanisms and optimization strategies for the interface state of solid‐state lithium‐ion batteries”

“…The formation of lithium dendrites can even pierce the diaphragm, causing the internal short circuit in the LIB, thermal runaway of the battery and combustion and explosion (Figure 6). 19,[97][98][99][100][101][102] As far as the origin of dendrite behavior is concerned, most researchers attribute it to thermodynamically heterogeneous e − /Li + transfer and heterogeneous nucleation and growth kinetics of electroplating/stripping Li (Figure 7). 12,20 The specific mechanism is still unclear.…”

“…The formation of lithium dendrites can even pierce the diaphragm, causing the internal short circuit in the LIB, thermal runaway of the battery and combustion and explosion (Figure 6). 19,97–102 …”

Benchmarking and Critical Design Considerations of Zero‐Excess Li‐Metal Batteries

“…So called zero-excess Li-metal batteries (ZELMBs), also called anode-free or anode-less batteries, represent a special type of LMB, in which the Li-metal anode is formed in situ during charging of the cell. A decent number of review articles has been published recently, summarizing the current state of the art of ZELMB with liquid electrolytes [1][2][3][4][5] and first studies employing solid-state electrolytes. [6,7] Besides major advantages regarding the ease of manufacturing as well as material and cost savings, ZELMBs offer the highest gravimetric (GED) and volumetric (VED) energy density among all cell concepts.…”

Improving Cycling Performance of Anode-Free Lithium Batteries by Pressure and Voltage Control

“…However, the zero-excess Li in AFLBs also leads to more severe capacity fading in AFLB cells as compared to LMBs with large amounts of excess Li in the anode. 5 The main reasons for the poor cycling stability of AFLBs include the irreversible consumption of electrolyte and Li inventory and the formation of an unstable solid−electrolyte interphase (SEI) on Li. This is because Li initially deposited on the Cu current collector exhibits a higher overpotential (which hinders Li nucleation and uniform growth) than that deposited on excess Li metal, as in the case of LMBs.…”

“…The limited amount of metallic Li deposited on the copper (Cu) current collector during the charge process can minimize the detrimental effects of large excess Li found in typical LMBs. However, the zero-excess Li in AFLBs also leads to more severe capacity fading in AFLB cells as compared to LMBs with large amounts of excess Li in the anode . The main reasons for the poor cycling stability of AFLBs include the irreversible consumption of electrolyte and Li inventory and the formation of an unstable solid–electrolyte interphase (SEI) on Li.…”