batteries. [4][5][6][7] Nevertheless, despite decades of intense research, intractable problems of safety hazard and low Coulombic efficiency (CE) still hinder the commercialization of Li metal batteries.It is well known that the extremely negative electrochemical potential of Li + /Li anode is able to reduce common organic electrolytes upon contact, leading to the formation of solid electrolyte interphase (SEI) layers at the electrode/electrolyte interface. [8][9][10] In addition, as a "host-less" electrode, the infinite relative volume change during Li stripping/plating fractures the mechanically fragile SEI, leading to the formation of cracks. The cracks expose the fresh Li underneath and locally enhance the Li-ion flux, which often results in dendritic Li deposition that can pierce through the separator and trigger an internal short circuit. [11][12][13][14] Moreover, the continuous breakdown and repair of SEI gradually consumes the active Li and electrolyte, resulting in rapid capacity fade and impedance rise. [15][16][17][18][19] To address these issues, quite a few approaches, such as electrolyte additives, [20][21][22][23] artificial SEI layers, [11,12,[14][15][16] modified electrodes, [24][25][26][27][28][29][30] and poly mer/solid electrolytes [31][32][33][34][35] have been proposed and certain progress has been achieved. Among these approaches to improve the Li metal anode performance, rational design of Li hosts to accommodate the tremendous volume change of Li metal during cycling is the most promising one. [18,[24][25][26][27][28][29][30][36][37][38] Carbonaceous materials with high electrical conductivity and superior (electro)chemical stability seem to be the suitable hosts for Li plating. [13][14][15]25,39] However, studies have illustrated that carbon substrates with appropriately designed nanoarchitecture exhibited unsatisfactory Li plating performances. The reason lies in the lithiophobic property of the bare carbon matrix, which leads to the isolated and randomly distributed nucleation sites for Li plating, hence resulting in the Li dendrites formation. [25,39,40] Recently, some theoretical calculations and experimental results showed that heteroatom doping could introduce lithiophilic functional groups (such as pyridinic and pyrrolic nitrogen) into the carbon matrix, thereby strengthening the Li affinity of the substrates. [41][42][43] As reported, in these structures, Li metal will preferentially nucleate at the lithiophilic sites due to strong adsorption energy, thus regulating the Li nucleation behavior and inhibiting Li dendrite growth to some extent. In addition to the Li adsorption energy, the stability of the coordination structure is also a major factor affecting the uniformity of Li deposition in a carbon For a long time lithium (Li) metal has been considered one of the most promising anodes for next-generation rechargeable batteries. Despite decades of concentrated research, its practical application is still hindered by dendritic Li deposition and infinite volume change of Li meta...

Rational structure design of the current collector along with further engineering of the solid‐electrolyte interphases (SEI) layer is one of the most promising strategies to achieve uniform Li deposition and inhibit uncontrolled growth of Li dendrites. Here, a Li2S layer as an artificial SEI with high compositional uniformity and high lithium ion conductivity is in situ generated on the surface of the 3D porous Cu current collector to regulate homogeneous Li plating/stripping. Both simulations and experiments demonstrate that the Li2S protective layer can passivate the porous Cu skeleton and balance the transport rate of lithium ions and electrons, thereby alleviating the agglomerated Li deposition at the top of the electrode or at the defect area of the SEI layer. As a result, the modified current collector exhibits long‐term cycling of 500 cycles at 1 mA cm−2 and stable electrodeposition capabilities of 4 mAh cm−2 at an ultrahigh current density of 4 mA cm−2. Furthermore, full batteries (LiFePO4 as cathode) paired with this designed 3D anode with only ≈200% extra lithium show superior stability and rate performance than the batteries paired with lithium foil (≈3000% extra lithium). These explorations provide new strategies for developing high‐performance Li metal anodes.

batteries is greatly limited by the highly insulating nature of S 8 /Li 2 S 2-x (x ≤ 1) and the dissolution of intermediate lithium polysulfides (Li 2 S n , 4 ≤ n ≤ 8) during charge/discharge process. [7][8][9] Over the past decades, massive efforts like encapsulating S 8 in conductive matrix, [10][11][12][13] protective coating layers, [14][15][16] and inducing interlayer between cathode and separator, [17][18][19] have been made to manipulate this deficiency, aiming to lighten shuttling and migration of Li 2 S n during long-term cycling and to improve the electrode kinetics. 2D materials with large specific area, such as graphene oxides (GOs), [20][21][22][23][24] MnO 2 , [25] Co 4 N, [26] MXene, [27] provide numerous anchoring sites and have been successfully employed as cathode hosts to suppress shuttling and migration of Li 2 S n in the Li-S batteries. Usually, heteroatoms doping is a general modification technique to further increase the polarity of 2D materials to adsorb Li 2 S n , giving birth to nitrogen-doped graphene, [28] nitrogen-doped MXene, [29] cobalt-doped porous carbon, [30] molybdenum-doped MoO 3 , [31] etc. However, the doping amount is very limited, which seriously restricts the improvement of their electrochemical performance. Comparing with the traditional doping strategy, intercalation can induce more heteroatoms in their van der Waals gap with good uniformity and change the properties of 2D materials more significantly. [32] For example, in our previous study, we proved that the n-type semiconducting SnS 2 can turn to a p-type semiconductor or metal after intercalation of different transition metal atoms. [33] Besides the electrical properties, the electrochemical properties of 2D materials might also be tuned effectively by this intercalation strategy.Here, ultrathin 2D layered α-MoO 3 nanoribbons with thickness of ≈10 nm have been synthesized and selected as the host. The strong polarity of MoO 3 together with its high specific surface area provides numerous active sites to bind sulfur species effectively, thus suppressing the "shuttle effect" obviously. Intercalation of metal tin (Sn) into van der Waals gap was further used to enhance the intrinsic conductivity of MoO 3 and improve the binding energy with sulfur species. Transmission electron microscopy (TEM) proved that Sn was inserted into the van der Waals gap of MoO 3 uniformly. First-principles calculations further certify that binding energy as large as 3.01 eV Heteroatom doping strategies have been widely developed to engineer the conductivity and polarity of 2D materials to improve their performance as the host for sulfur cathode in lithium-sulfur batteries. However, further improvement is limited by the inhomogeneity and the small amount of the doping atoms. An intercalation method to improve the conductivity and polarity of 2D-layered α-MoO 3 nanoribbons is developed here, thus, resulting in much improved electrochemical performance as sulfur host with better rate and cycle performance. The first principle calculations show t...

Two-dimensional (2D) MXene-loaded single-atom (SA) catalysts have drawn increasing attention. SAs immobilized on oxygen vacancies (O V ) of MXene are predicted to have excellent catalytic performance; however, they have not yet been realized experimentally. Here Pt SAs immobilized on the O V of monolayer Ti 3 C 2 T x flakes are constructed by a rapid thermal shock technique under a H 2 atmosphere. The resultant Ti 3 C 2 T x -Pt SA catalyst exhibits excellent hydrogen evolution reaction (HER) performance, including a small overpotential of 38 mV at 10 mA cm −2 , a high mass activity of 23.21 A mg Pt −1 , and a large turnover frequency of 23.45 s −1 at an overpotential of 100 mV. Furthermore, density functional theory calculations demonstrate that anchoring the Pt SA on the O V of Ti 3 C 2 T x helps to decrease the binding energy and the hybridization strength between H atoms and the supports, contributing to rapid hydrogen adsorption−desorption kinetics and high activity for the HER.

and long cycle life are urgently pursued. [1][2][3][4] However, current lithium-ion batteries (LIBs) have almost reached their theoretical limitation. [5][6][7][8] So, developing novel electrode materials with high energy and power densities as well as long cycle life is of great significance. Li metal electrodes, hailed as "Holy Grail" electrode, show incomparable advantages including high specific capacity (3860 mAh g −1 ) and low electrochemical potential (−3.040 V vs standard hydrogen electrode) and have been considered as the most promising next-generation electrode materials for Li-S, Li-air batteries, and so on. [9][10][11] However, the lithium metal batteries (LMBs) always suffer dendritic Li during the repeated plating/stripping process, which not only causes the formation of lots of "dead Li" and blocks the Li + / electron transportation between the bulk Li and the electrolyte and furtherly results in the low coulombic efficiency (CE) but also is the main culprit in piercing the separator, giving rise to the internal short circuits and finally leading to the serious security risks. [12][13][14] In addition, the unstable solid electrolyte interphase (SEI) is formed repeatedly on the surface of Li metal during the charge-discharge process, which leads to the nonuniform Li ionic flux and further aggravates the growth of dendritic Li as well as depletes the electrolyte. [15][16][17][18] All these disadvantages lead to low CE and poor cyclability and further impede the commercialization of LMBs.In recent years, many attempts have been exerted to eliminate the formation of Li dendrite and enhance the cyclability of LMBs. Fabricating stable intrinsic SEI layer by the liquid electrolyte additives can improve partly the electrochemical performance. [19][20][21][22][23] Similarly, preparing artificial SEI layer with high Young's Modulus on the surface of the Li metal is another common way to suppress the dendrite growth. [24][25][26][27] Modified separator with functional materials for LMBs is also adopted to inhibit the formation of dendritic Li and shows some progress. [28] Solid electrolytes with high Young's modulus have exhibited good resistance to lithium dendrites in previous reports. [29,30] Although some good results are achieved by these strategies, the complicated synthesis process, high cost, great weight or instability during long-term cycle limit their practical applications. More recently, designing 3D collectors with a lithiophilic surface as host for storing Li metal, such as modified 3D Cu foam or Ni foam, shows some progress since large specific area of 3D structure is beneficial to decreasing the local current density and regulating the distribution of electric fieldThe application and development of lithium metal battery are severely restricted by the uncontrolled growth of lithium dendrite and poor cycle stability. Uniform lithium deposition is the core to solve these problems, but it is difficult to be achieved on commercial Cu collectors. In this work, a simple and commercially viable stra...