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Li metal electrodes have the potential to increase the energy density of conventional lithium-ion batteries by up to 60%. However, challenges regarding the cycling efficiency and safety of these electrodes still remain. Effective surface treatments seem to be a promising approach for resolving issues such as dendrite formation or excessive reaction with the electrolyte. LiF has been reported to exhibit most of the properties required of a coating material in this context, offering high electro-/chemical stability, mechanical strength, high surface energies, etc. Nevertheless, contradicting reports on the effectiveness of LiF coatings to improve the cycling efficiency of Li metal electrodes raise doubts on its effectiveness to protect the Li metal surface. The mechanism of protection for this material is also not well understood. Thus, a comparative study was conducted, selecting three different approaches for the synthesis of a LiF coating on Li metal and following with detailed electrochemical analysis. Using the same experimental setup for all samples enabled direct comparison between the selected coatings, and subsequently, a reliable evaluation on the effectiveness of LiF as protective coating.

As the automotive industry shifts from internal combustion engine (ICE) vehicles to electric vehicles (EVs), many countries are setting new strategies in their transportation sector. The Li-ion battery is currently the most common battery used in EVs due to its high energy density, durability, safety, and cost competitiveness. Nickel is predicted to be an essential component for the lithium nickel cobalt manganese oxide (NMC) as a cathode material of choice for EV applications. Indonesia, one of the world’s largest nickel ore suppliers, put an export ban on nickel ore effective from 2020. The bold movement was intended to initiate the domestic EV industry and encourage investors abroad to drive their manufacturing activities into the country. On the other hand, the global Li-ion battery manufacturers who imported nickel from Indonesia had to restrategize their businesses. This review discussed the chronological events leading to the ban and after the ban from the media, government regulations, and literature reviews. The authors of this study also conducted interviews and attended seminars with the national experts and key players in the battery and EV industry to gain their most pertinent insights. The SWOT analysis of the reviewed materials indicated that while the Indonesian battery industry is still new, it needs to diversify its research and development activities and collaborate internationally to optimize the utilization of its resources and meet the purchasing power of the domestic EV market. Finally, this study summarized six key factors to support Indonesia’s ambition to be a new regional hub for EVs. These factors are: (1) pricing, (2) technology, (3) policy, (4) investment, (5) infrastructure, and (6) compliance with sustainability standards.

Coating conducting polymers onto active cathode materials has been proven to mitigate issues at high current densities stemming from the limited conducting abilities of the metal-oxides. In the present study, a carbon coating was applied onto nickel-rich NMC622 via polymerisation of furfuryl alcohol, followed by calcination, for the first time. The formation of a uniform amorphous carbon layer was observed with scanning- and transmission-electron microscopy (SEM and TEM) and X-ray photoelectron spectroscopy (XPS). The stability of the coated active material was confirmed and the electrochemical behaviour as well as the cycling stability was evaluated. The impact of the heat treatment on the electrochemical performance was studied systematically and was shown to improve cycling and high current performance alike. In-depth investigations of polymer coated samples show that the improved performance can be correlated with the calcination temperatures. In particular, a heat treatment at 400 °C leads to enhanced reversibility and capacity retention even after 400 cycles. At 10C, the discharge capacity for carbon coated NMC increases by nearly 50% compared to uncoated samples. This study clearly shows for the first time the synergetic effects of a furfuryl polymer coating and subsequent calcination leading to improved electrochemical performance of nickel-rich NMC622.

In this work, the effect of Cr3+ partial substitution on vanadium site in monoclinic lithium vanadium(III) phosphate (LVP) structure resulting in compounds with general formula: Li3V2- xCr x(PO4)3-C ( x = 0, 0.05, 0.1, 0.15) was studied. A two-step sol-gel combustion method was employed in syntheses. The samples were characterized by X-ray powder diffraction, scanning electron microscopy, coupled plasma optical emission spectroscopy, and flash combustion. The electrochemical performance of the active materials was examined through rate capability tests and cyclic voltammetry. The unsubstituted compound LVPC delivers higher capacity compared to the Cr-containing samples due to chromium inactivity in the potential range 3.0–4.4 V vs. Li/Li+. However, the Cr-substituted materials show better overall capacity retention (97–97.6%) in contrast to Li3V2(PO4)3-C (96%) in long cycling.

We investigated the effect of different electrolyte additives such as vinyl carbonate (VC), succinic anhydride (SA), and lithium bis(oxalato)borate (LiBOB) on the chemical composition of Solid Electrolyte Interphase (SEI) layer and the electrochemical performance of Si/MC electrodes. The electrochemical behavior of the Si/MC electrodes was evaluated by galvanostatic charge/discharge and rate capability tests. It was found that various electrolyte compositions result in the formation and the resulting properties of the SEI of the electrodes with different compounds. From X-ray Photoelectron Spectroscopy (XPS) analysis, the electrodes cycled in SA- and LiBOB-containing electrolytes show a higher amount of lithium carbonates and a thicker SEI layer than those in standard and VC-containing electrolyte. The electrode with VC 5w% shows an excellent reversible capacity of ∼1100 mAh g −1 up to 100 charge-discharge cycles.

Tin (IV) sulfide is a promising anode active material for lithium ion batteries due to its relatively high reversible capacity of 644 mAh/g, which is more than one and a half times that of graphite. During lithiation of tin (IV) sulfide, an inert Li2S matrix is formed in the first discharge cycle, which serves to accommodate the mechanical stresses associated with the volume expansion of tin during the successive LixSn alloying and de-alloying reactions. In order to improve the electrochemical performance of tin (IV) sulfide further, fundamental understanding and insights into the thermodynamics, phase formation, and driving forces for the lithiation reactions are still required. Therefore, in this work, a computational thermodynamics approach was combined with ex-situ XRD investigations of electrodes during the discharge reaction as well as galvanostatic intermittent titration technique (GITT) experiments in order to clarify the lithiation thermodynamics of tin (IV) sulfide. Based on the experimental data, a one-phase mechanism was suggested for the intercalation of lithium into SnS2, a thermodynamic model was developed to describe the intercalation reaction and the expected open circuit voltages were calculated.

Lithium Ion Batteries (LIB) find not only wide use in portable devices and consumer electronics, but also attract increasing attention in stationary energy storage and the automotive sector. In this regard, LIBs play a significant role as intermediate energy storage due to their high volumetric and gravimetric energy, high power density, and long cycle life. To achieve the required performance, the interaction of novel anode and cathode materials is of paramount interest. Particularly, the safety of cell operation must be assessed with respect to the formation of volatile and reactive species during cycling which can negatively alter cell components. Gas chromatography mass spectroscopy (GCMS) has proven to be a reliable tool for species detection. Unfortunately, conventional GC systems lack time resolution for in-situ gas analysis regarding fast processes, for example battery failure. Therefore, developing operando testing methods with improved time resolution is key to giving insight into electrolyte alterations during battery operation. Here one of them, a novel multiplex injection method is presented as a monitoring technique for gas species arising from the decomposition of conventional LIB electrolytes. The combination of the multiplexing technique and GCMS allows the analysis of fast decomposition processes by 15 fold increase of time resolution compared to conventional gas chromatography. In addition, FTIR allows online monitoring of selected vibration bands. Commercially produced pouch cells were monitored with respect to evolving gas species during battery operation under overcharge conditions. For the decomposition of LiPF6 / organic carbonate- based electrolytes alkanes, alcohols, ethers, esters, aldehydes and also derivatives that appear in the presence of hydrofluoric acid such as fluorinated alkane species, have been evaluated. The author gratefully acknowledges the FFG (Austrian Research Promotion Agency) for funding this research within project No. 858298.

Due to its theoretical capacity of 960 mAh/g, which is approximately two and a half times that of graphite (372 mAh/g), as well as its natural abundance, Sn is as an interesting anode active material to replace the currently used graphite in lithium ion batteries. However, Sn-based anodes have not been commercialized because they suffer from prohibitively large volume expansions due to the formation of brittle LixSn alloys during lithiation (>185 % for full lithiation to Li17Sn4). These volume changes lead to extensive crack formation, loss of electrical contact between particles, pulverization of the electrode during cycling, lithium trapping, and the growth of an unstable SEI. One way to take advantage of the high capacity of Sn and simultaneously overcome its degradation mechanisms is to use Sn-based chalcogenide compounds such as SnS2 and SnS as anode active materials. During lithiation of these compounds, a composite electrode structure consisting of active Sn particles embedded in an inactive Li2S buffer matrix is formed, which is expected to accommodate the mechanical stress of the alloying and de-alloying reactions during cycling. Although several authors have studied the lithiation of SnS2 via in-situ electron microscopy techniques, there are still many open questions regarding 1) the amount of lithium which can be intercalated into the layered structure of SnS2, 2) the structural changes of SnS2 during lithiation, and 3) if the reaction occurs via a one-phase or a two-phase process. Additionally, there are no published phase diagrams of the Li–Sn–S system at room temperature, which could be used to explore the changes in the electrode constitution during lithiation and de-lithiation. In fact, only Hwang et al. [1] modelled the phase equilibria in the Li–Sn–S at 0 K using density functional theory (DFT) calculations, but their data are incomplete since they omitted the Sn2S3, Li7Sn3 and Li5Sn2 phases and did not take into account the electrochemically and chemically observed solubility of lithium in SnS2. Therefore, in this work, the CALPHAD (CALculation of PHAse Diagrams) and computational thermodynamics methods were combined with key experiments to 1) understand the electrochemical lithiation of SnS2, 2) model the phase development during the equilibrium and non-equilibrium lithiation of the SnxSy tin sulfide compounds, and 3) evaluate the energetics of the competing lithiation reactions for the first time. Firstly, a thermodynamic description for the ternary Li–Sn–S system was developed by combining the descriptions of the Li–Sn system from Reichmann et al. [2] with that for the Sn–S system from Lindwall et al. [3] and the Gibbs free energy function for Li2S from the Scientific Group Thermodata Europe (SGTE) [4]. The ternary database was used to calculate the Li–Sn–S phase diagram at room temperature and simulate the titration curves for the equilibrium lithiation of the tin sulfide compounds. At the same time, homogeneous and heterogeneous Sn–S powder samples were processed as slurries, coated onto copper-foil substrates and subjected to electrochemical testing vs Li+/Li. The galvanostatic intermittent titration technique was used to characterize the quasi-equilibrium open circuit potentials of the electrodes during full and partial de-/lithiation in the potential range of 0.01-2.5 V. Additionally, a full profile, Rietveld refinement of the ex-situ XRD patterns of selected electrodes was performed in order to assess the phase development and structural changes of the electrode active materials during titration. These data were used to suggest a one-phase mechanism for the equilibrium lithiation of SnS2 after voltage relaxation. Finally, the electrochemical and crystallographic data were used to develop a new thermodynamic model to describe the intercalation of lithium ions into the layered SnS2 structure and calculate the measured open circuit voltage values. Using this description, it could be shown that lithiated SnS2 is indeed a metastable phase, which forms due to the energetic feasibility of the intercalation mechanism compared to the equilibrium conversion reaction. References [1] S. Hwang, et al., ACS Nano, 12, (2018), 3638-3645. [2] T.L Reichmann, D.J. Li, D.M. Cupid, Phys. Chem. Chem. Phys. 20 (2018), 22856-22866 [3] G. Lindwall, S.L. Shang, N.R. Kelly, T. Anderson, Z.K. Liu, Solar Energy (2016) 314-323 [4] SGTE Substance Database SGSUB, Version 4, 2008

Silicon/mesoporous carbon (Si/MC) composites with optimum Si content, in which the volumetric energy density would be maximized, while volume changes would be minimized, have been developed. The composites were prepared by dispersing Si nanoparticles in a phenolic resin as a carbon source, subsequent carbonization, and etching with hydrofluoric acid (HF). Special attention was paid to understanding the role of HF etching as post-treatment to provide additional void spaces in the composites. The etching process was shown to reduce the SiO2 native layer on the Si nanoparticles, resulting in increased porosity in comparison to the non-etched composite material. For cell optimization, vinylene carbonate (VC) was employed as an electrolyte additive to build a stable solid electrolyte interphase (SEI) layer on the electrode. The composition of the SEI layer on Si/MC electrodes, cycled with and without VC-containing electrolytes for several cycles, was then comprehensively investigated by using ex-situ XPS. The SEI layers on the electrodes working with VC-containing electrolyte were more stable than those in configurations without VC, this explains why our sample with VC exhibits lower irreversible capacity losses after several cycles. The optimized Si/MC composites exhibit a reversible capacity of ~800 mAhg&minus, 1 with an average coulombic efficiency of ~99 % over 400 cycles at C/10.

Silicon is a promising candidate for anodes in lithium-ion batteries (LIB) due to its high theoretical capacity. However, Si has low electrical conductivity (theoretical: 6.7 x 10-4 S cm-1). Proper conductive additive is needed in order to improve the electrical conductivity of Si-based anodes. Here we focus on applying two commercial conductive addictives: graphite and carbon black Super C65 for silicon-mesoporous carbon (Si/MC) composite anodes. The structure and morphology of the electrodes were characterized by nitrogen adsorption, scanning electron microscopy (SEM), and focus ion beam/transmission electron microscopy (FIB/TEM). Furthermore, the electrochemical performance of the electrodes was characterized by cyclic voltammetry, galvanostatic charge/discharge tests, and impedance spectroscopy. In principles, our work could be effective for the choice of conductive additives to improve the electrical performance of Si/MC anodes.

Silicon exhibits the highest theoretical capacity of 4200 mAh g-1, which is 10 times more than the capacity of graphite. Therefore, Si is a promising candidate for anode in lithium-ion batteries. However, Si has low electrical conductivity (theoretical: 6.7 x 10-4 S cm-1). To reach the high performance anode, the proper conductive additives are still needed in order to improve the electrical conductivity of Si-based anode. Here we investigated the effects of conductive nano-graphite and Carbon Black (CB65) on electrochemical performance of silicon-mesoporous carbon composite anode (Si/MC). The material has been synthesized by pyrolysis of polymer aerogel with embedded Si nanoparticles. The electrode was made by 75% active material, 15% conductive additive, and 10% polyacrylic acid (PAA) binder. The electrochemical characterization using impedance spectroscopy, voltammetry, and galvanostatic charge/discharge tests were conducted for both samples. Impedance spectroscopy showed that Si/MC anode with conductive graphite exhibited lower charge-transfer resistance (Rct ≈ 150 Ω), compared to those with carbon black (Rct ≈ 380 Ω). The collected results showed that the graphite additive improved significantly the electrochemical performance of Si/MC anode. In addition, the thermal and long cycling tests will be demonstrated.