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Abstract A Li/LiF-LiCl-LiBr/Sn battery cell is prepared for the first time to investigate the feasibility of pure tin metal as an environmentally friendly cathode material in the liquid metal battery. The Li-Sn cell can achieve the mean voltages of 0.820 and 0.607 V during charge and discharge at 100 mA cm−2, respectively. Increasing the discharge current density from 100 to 700 mA cm−2 results in 1.3% capacity loss, and the capacity loss is 12.4% when the charge current density increased from 100 to 1000 mA cm−2. This high rate capability of the cell is due to ultrafast charge-transfer kinetics at the interface of liquid electrode and liquid electrolyte. The Li-Sn cell exhibits a capacity retention of 94.0% after 220 cycles. The capacity loss originates from the loss of active Sn by forming SnFe and CrSn 2 intermetallics in side reaction between the Sn and stainless steel case, and these intermetallics are inert to lithium within the voltage window of 0.5–1.2 V. [ABSTRACT FROM AUTHOR]

The effects of an Li-Al layer on the modified-Li anode based on solid state batteries are studied. The structure, surface morphology, and cyclic stability of the modified-Li anode are examined by X-ray diffraction spectroscopy, scanning electron microscopy, and electrochemical tests. Results show that interphase layer can prevent Li from reacting with Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 and displays a much better cycling stability compared with the bare-Li anode used in symmetric cells. The assembled solid state batteries with modified-Li anode and LiMn 0.8 Fe 0.2 PO 4 cathode can deliver an initial discharge capacity of 153 mAh g −1 with good cyclic stability and rate performance at 50 °C. The reason for this is that the Li-Al alloy interphase layer can prevent localised Li enrichment, then suppress lithium dendrite growth, and the Li-Al layer on the anode possesses good stability in the presence of Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 powder and better interphase contact results between the anode and solid electrolyte in solid state batteries. [ABSTRACT FROM AUTHOR]

Controlling the formation of the solid electrolyte interphase (SEI) layer of the future generation of lithium metal batteries is critical in optimising both their safety and performance. Unfortunately, lithium and lithiated anode materials are inherently susceptible to unwanted side-reactions including lithium metal dendrite formation, which compromises cell safety. This aberrant lithium re-deposition process ocurring on the lithium anode originates at the electrode surface, with few considering the initial adsorption of electrolyte components onto lithium metal, and the effect this has on the formative stages of SEI layer development. In this work, density functional theory calculations and ab initio molecular dynamics simulations are used to determine the preferred adsorption sites and orientations of two common battery electrolytes, ethylene carbonate (EC) and propylene carbonate (PC) on a Li(001) surface. Three types of orientations were found for both EC and PC each consisting of O atoms ionically bonded to surface Li atoms. Both molecules were found to weakly chemisorb with a similar stability to each other. Ab initio molecular dynamics simulations were used to determine the dissociation mechanism of both molecules on the surface. EC was shown to decompose within 7 ps of simulation time by first accepting an electron from the Li surface and breaking the bond between the carbonyl C and ring O. It then accepted another electron from the Li surface and the bond between the carbonyl C and the other ring O breaks. PC decomposition proceeded via a similar pathway over a longer timescale by accepting an electron from the Li surface and breaking the bond between the carbonyl C and a ring O atom. In contrast to EC, the breaking of the other carbonyl C ring O bond was not seen for PC within the 20 ps simulation, which has been ascribed to the greater stability provided by the methyl group. [ABSTRACT FROM AUTHOR]

A graphene surface coating strategy (G@LATP), to modify and improve the interfacial characteristics between the Lithium Aluminum Titanium Phosphate (LATP) electrolyte and different anodes, such as Li metal and Si film has been proposed. As a result, the Li/Li symmetric cell with graphene coating modified LATP electrolyte exhibits excellent cyclic stability, even at large current densities of 0.5 mA·cm−2 and 1 mA·cm−2. The modified Li/G@LATP/LiFePO 4 solid-state full cell is delivering a discharge specific capacity of 136 mAh· g −1 after 200 cycles at a current density of 0.1 mA·cm−2, corresponding to a capacity retention of 86.1%. The graphene coating technique also led to improved cyclic stability in the Si/Si symmetric cell with modified LATP electrolyte at current densities of 0.1 mA·cm−2 and 0.3 mA·cm−2, with polarization voltages of 0.063 V and 0.27 V after cycling for 1000 h, respectively. Moreover, the Si/G@LATP/LiFePO 4 full cell shows an outstanding discharge specific capacity of 161 mAh· g −1 at its 2nd cycle, with a capacity retention of 92.9% after 200 cycles. These results show that graphene coating of the LATP electrolyte is a facile and effective method to improve the interfacial characteristics of Li/LATP and Si/LATP. [ABSTRACT FROM AUTHOR]

Hybrid silica-based nanofillers were synthesised by grafting short chains of poly(ethylene glycol) (PEG) with different molecular weight on the surface of SiO 2 porous nanoparticles. Based on this approach, homogeneous poly(ethylene oxide) (PEO)-based ceramic-in-polymer solid-state electrolytes with SiO 2 loadings up to 23 wt% were obtained, thanks to the high compatibility between the two phases endowed by the grafted PEG chains. These electrolytes showed satisfying ionic conductivity and excellent resistance against dendrite piercing that enabled long operation, for more than 350 h, under continuous stripping/plating of lithium in symmetric Li/electrolyte/Li cells. Additionally, the operating life of these devices was improved by the self-healing reaction between Li dendrites and silica fillers, being able to reinstate the cycling after short circuit. Finally, a lithium metal full cell, equipped with LiFePO 4 positive material and the solid-state electrolyte containing 18 wt% of SiO 2 , demonstrated high stability against dendrite penetration and discharge capacity at 70 °C comparable to cells based on liquid analogues. [ABSTRACT FROM AUTHOR]

The effects of temperature on the discharge and hydrogen evolution of lithium anode in 4M (molL−1) LiOH solutions were investigated via hydrogen collection, polarization and SEM (scanning electron microscope). It was found that the hydrogen evolution rate is low below 30°C with low discharge current density and the discharge current density is high over 30 with high hydrogen evolution rate. The lithium anode shows the better electrochemical performance with high discharge current density, low hydrogen evolution, and less porous film at 30°C at 0.94ms−1 in 4M LiOH solutions. [ABSTRACT FROM AUTHOR]

For the most ordinary graphite negative electrode, the inserted Li+ occupies interlamellar spacing in the graphite lattice, and transform into Li-graphite phase (Li X C 6). During the high charging rates, Li+ is adsorbed preferentially on lithiated Li X C 6 which promotes Li crystallization and grows into uncontrollable dendrites. Thus, how to apply this defect to advantage and extend into stabilizing Li metal plating is ignored in practice. Herein, expansion graphite (EG) is ornamented as lithiophilic porous carbon basement which leverages insertion Li+ as inducing sites. In this way, Li metal grows preferentially on the lithiated graphite layer and ensuring the plating/stripping stably and suppressing the growth of lithium dendrites. Consequently, a stable polarization of 49.5 mV is obtained with EG anode in a symmetrical cell with 320 h even at a high current density of 10 mA cm−2 and high areal capacity of 10 mAh cm−2. Additionally, the resulting EG@Li assembled LFP full cell could deliver 85% capacity retention after 500 cycles. The in-situ inserted Li+ occupies interlamellar spacing in the graphite lattice, and transform into Li-graphite phase (Li X C 6) which is lithiophilic sites. Expansion graphite (EG) is ornamented as lithiophilic porous carbon layer which leverages insertion Li+ as inducing sites. Li metal grows preferentially on lithiated graphite layer and ensuring the plating and stripping stably with high areal capacity. [Display omitted] [ABSTRACT FROM AUTHOR]

The performance of a liquid metal battery can be significantly enhanced by lowering the cell operating temperature through alloying of the cell components. The effect of alloying pure tin metal, a cathode material for liquid metal batteries, on electrochemical properties is investigated by preparing a Li|Sn-Bi (Sn:Bi = 56:44 at%) battery cell. The Li|Sn-Bi cell achieves mean voltages of 0.856 and 0.683 V during charging and discharging, respectively, at 100 mA cm−2, which are 0.039 and 0.067 V higher than those of the Li|Sn cell. The Li|Sn-Bi cell exhibits a high rate capability owing to the low charge-transfer resistance between the liquid electrodes and liquid electrolytes. The charge and discharge capacity losses are 6.5% and 18.6%, respectively, at 1000 mA cm−2 compared with those at 100 mA cm−2. The Li|Sn-Bi cell can be discharged even at 1000 mA cm−2 owing to an increase in the mean discharge voltage by the alloying of tin with bismuth. The Li|Sn-Bi cell also exhibits improved cycle performance, with a capacity retention of 94.2% after 1000 cycles and a capacity decay of 0.0065% per cycle. This is attributed to the lack of formation of intermetallic byproducts between Bi and the stainless steel case and suppression of the side reaction between Sn and stainless steel by bismuth in the Sn-Bi lamellar microstructure. Thus, using a Sn-Bi alloy as the positive material significantly improves battery performance, making the Li|Sn-Bi cell a good candidate for stationary storage applications. [ABSTRACT FROM AUTHOR]

• A dimensionally stable composite Li anode is fabricated by using Ag-modified Cu foam. • The composite Li anode shows bulk and microstructural stability, but interface instability. • Uniform and large-capacity lithium plating within Ag-modified Cu foam is achieved. Lithium metal is recognized as the "Holy Grail" of anode materials for high-energy-density batteries. However, the application of the lithium anode is seriously hindered due to its instability especially during the large-capacity lithium stripping/plating process. In this study, a dimensionally stable Li composite electrode is fabricated by electrodepositing lithium on Ag-modified Cu foam. The Li-Ag alloy formed during the initial plating shows micro-structural affinity to lithium and promotes the subsequent uniform Li stripping/plating on the Cu skeleton. The symmetric cell with Li/Ag-modified Cu composite electrode shows much-improved stability as compared to both the Li/3D Cu composite and Li plate electrodes. By investigating the electrochemical performance of the full cells with Li 4 Ti 5 O 12 cathode, we find the interface stability of the Li composite electrode is deteriorated because of the increase of specific surface area. This work indicates that both dimensional and interface stabilities of lithium anodes are important for fabricating practical secondary lithium batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The electrochemical behavior of lithium in lithium hydroxide solution with sodium nitrite has been investigated in this paper. The results show that the hydrogen evolution rate decreases with increasing sodium nitrite concentration. Through potentiostatic polarization and scanning electron microscope (SEM), we found that the current efficiency keeps nearly unchanged with sodium nitrite introduction to the solutions. The porosity of the lithium surface film decreased due to the precipitation of LiOH promoted by sodium nitrite. [Copyright &y& Elsevier]

Lithium-sulfur batteries have high theoretical energy density, but still suffer from polysulfide shuttle effect and lithium dendritic growth. Here, we present a rollable and swellable 3D cable-like carbon material consisting of porous fibrous carbon coated with nitrogen-doped graphene foam as self-standing host for both sulfur cathode and lithium anode. A cathode exhibits high areal energy density (10.2 mWh cm−2) and power density (5.1 mW cm−2) with 92.2% retention for 200 cycles at 0.5 C, and a full cell delivers 525 mAh g−1 (1.8 mAh cm−2) after 100 cycles at 0.5 C with a fade rate of 0.14% per cycle. We found dense urea molecules can assist graphene foam formation, cellulose fibers activation and high-level nitrogen (7.58 atom% N) doping, and the resulting cable-like carbon can improve electrocatalytic polysulfide redox kinetics and lithium dendrite inhibition. This work provides a strategy and understanding of modifying commercial cloth with graphene for dual electrode of Li–S battery. [ABSTRACT FROM AUTHOR]