Engineering of lithium-metal anodes towards a safe and stable battery

Abstract

Currently, the state-of-the-art lithium-ion batteries (LIBs) are the most widely used energy storage devices and have brought a great impact on our daily life. However, even many strategies have been reported to improve the energy density, these LIBs still can not meet the rapidly growing demand from the many lately emerged devices. During the pursue of higher energy densities, lithium-metal batteries (LMBs) have been the most promising candidates of the next-generation energy storage devices. Unfortunately, the Li-metal anode usually induces severe safety concerns and inferior cycle performance, because of the dendrite growth, high reactivity, and infinite volume changes of Li metal. As a result, these problems limit the commercial application of LMBs and must be resolved prior to the practical deployment of LMBs. In this review, we will firstly discuss the failure mechanisms of Li-metal anodes and introduce latest characterization technologies to study dendritic Li formation. The advances to improve the safety and performance of Li metal anode through electrolyte modification, interfacial engineering, solid-state electrolyte incorporation, and host materials design will then be comprehensively summarized and discussed. Lastly, we will conclude by summarizing the challenges in the current research on LMBs and highlight the future perspectives as well. Through this review, we hope to present the latest developments of the Li metal anode materials for the readers, and also shed light on the possible solutions for the current issues in order to accelerate both fundamental research and practical deployment of the various LMBs.

A Ceramic‐PVDF Composite Membrane with Modified Interfaces as an Ion‐Conducting Electrolyte for Solid‐State Lithium‐Ion Batteries Operating at Room Temperature

“…[49] We measured the RT ionic conductivities (Table 1) of the SSE-X membranes, while the corresponding Nyquist plots are shown in Figure 1b. [42] The thermal stability and mechanical properties are also of critical importance for the development of SSEs. In the SSE-X series, SSE-10 has the best conductivity with a tenfold improvement over SSE-0.…”

“…26 O 11.79 was reported to be~0.25 mS cm À 1 , while the grain boundary conductivity was determined to be lower than 10 À 8 S cm À 1 . [39][40][41][42][43] Moreover, since ceramic SSEs are brittle, some researchers have questioned their suitability in some applications, most notably in electric vehicles. [1,25,38] Also, many solid electrolyte materials are unstable at high voltages and may react with the materials of the electrodes.…”

Self‐Formed Protection Layer on a 3D Lithium Metal Anode for Ultrastable Lithium–Sulfur Batteries

“…standard hydrogen electrode), and alow gravimetric density (0.59 gcm À3 ), is regarded as the preferred anode materialf or Li-S batteries. [9] To ensure that the energyd ensity of the Li-S battery exceeds the state-of-art Li-ion battery,t he cycling area capacity of the cathode side needs to exceed at least 4mAh cm À2 .T hat meansa t least a2 0mmv ariation of the thickness of the corresponding anode side, which is ah uge volume change for an SEI layer on the lithium metal surface and will aggravate the attenuationo f the battery capacity and efficiency.A dditionally,t he commonly used lithium foil is unevena tt he microscale in the horizontal and vertical direction, leading to an uneven local current density distributioni nt he charge-dischargep rocess, whicha ggravates the lithium dendritegrowth. [7] The SEI layer is intrinsically brittle and cracks owing to the volumec hange effect during the Li deposition and dissolution process, which exposes fresh lithium to the electrolyte to form an ew SEI layer.…”

Electromigration in Lithium Whisker Formation Plays Insignificant Role during Electroplating

“…In contrast to graphite, which has nearly constant surface area stabilized by a solid-electrolyte interphase (SEI) upon the first few lithiation cycles, "dendrites" create new surface in each cycle, thus the electrolyte is being continuously consumed for SEI formation on each battery charge. [14][15][16] At the same time recent observations of competing tip and root growth of lithium needles [17][18][19][20][21] and its microstructure revealed by cryo-TEM [22] contradict with many of suggested theoretical models. [3] In addition, non-uniform metal deposition leads to capacity loss due to so-called "dead lithium", which forms when such needle-or bush-like structures dissolve at the base during discharge and loose electrical contact with the electrode.…”

“…Lithium tends to form various needle-like or bush-like structures, often called "dendrites" in literature. [3,[13][14][15][16] These routes for suppressing "dendrites" or mossy lithium formation typically rely on the theoretical considerations, which were suggested decades ago, but are still in focus in current reviews. [2] Needle-like structures can also reach the opposite electrode even causing internal short-circuits and fire.…”