Generation Lithium-ion Batteries Research Articles

Outstanding electrochemical performance of high-voltage LiNi1/3Co1/3Mn1/3O2 cathode achieved by application of LiPO2F2 electrolyte additive

Layered LiNi1/3Co1/3Mn1/3O2 (LNCM) cathode has received extensive attention because of its high specific capacity at high voltage (4.5 V). While the unsatisfactory electrochemical performance at high voltage hinders its practical application in next generation lithium ion batteries. Herein we demonstrate that simply application of lithium difluorophosphate (LiPO2F2) electrolyte additive significantly improves the electrochemical performance of high voltage LNCM/Li cell, at room and low temperature (−10 °C). Capacity retention of high voltage LNCM/Li cell with 3 wt. % LiPO2F2 additive achieves 89% after 250 cycles at room temperature and 94% after 200 cycles at low temperature in comparison with that of 61% and 10% without additive. Even discharging at 10 C, the LNCM/Li cell with 3% LiPO2F2 still delivers an initial capacity of 144 mAh g−1 and maintains at 69 mAh g−1 after 1000 cycles at room temperature. While the one without additive drops to 0 mAh g−1 after about 350 cycles. The improved cyclic stability and rate capability of high voltage LNCM is mainly ascribed to the steady low impedance cathode electrolyte interphase (CEI) film created by 3% LiPO2F2 additive, which greatly hinders the subsequent electrolyte oxidation, electrode structural destruction and increase of electrode polarization during cycling.

Theory of the Double Layer in Water-in-Salt Electrolytes.

One challenge in developing the next generation of lithium-ion batteries is the replacement of organic electrolytes, which are flammable and most often contain toxic and thermally unstable lithium salts, with safer, environmentally friendly alternatives. Recently developed water-in-salt electrolytes (WiSEs), which are nonflammable, nontoxic, and also have enhanced electrochemical stability, are promising alternatives. In this work, we develop a simple modified Poisson-Fermi theory for WiSEs, which demonstrates the fine interplay between electrosorption, solvation, and ion correlations. The phenomenological parameters are extracted from molecular dynamics simulations, also performed here. The theory reproduces the WiSEs' electrical double-layer structure with remarkable accuracy.

Cornlike ordered N-doped carbon coated hollow Fe3O4 by magnetic self-assembly for the application of Li-ion battery

Cornlike ordered N-doped carbon coated hollow Fe3O4 (OH-Fe3O4@NC) composites are prepared through a facile strategy. The unique structure is composed of hundreds of N-doped carbon coated hollow Fe3O4 nanospheres. Successive carbon shell and hollow structure address the irreversibility issue of Fe3O4-based electrodes. Owing to the unique cornlike ordered structure, the as-prepared OH-Fe3O4@NC composites exhibit appealing electrochemical performance as anode materials for lithium-ion batteries (LIBs). It delivers a high reversible capacity of 1316 mA h g−1 at 0.1 A g−1 after 50 cycles and a remarkable rate performance (725, 551 and 361 mA h g−1 at 1, 4, and 10 A g−1, respectively). Our results demonstrate that the OH-Fe3O4@NC composites are the promising anode materials with high capacity for next generation LIBs.

Simple co-precipitation synthesis of high-voltage spinel cathodes with different Ni/Mn ratios for lithium-ion batteries

The high-voltage spinel is a promising cathode material in next generation of lithium-ion batteries. Samples LiNi0.5 − xMn1.5 + xO4 (x = 0, 0.05, 0.1) are synthesized by a simple co-precipitation method, in which pH value and temperature conditions do not need control. In the simple co-precipitation method, NaHCO3 solution is poured into transition metal solution to produce precursor. Ni and Mn are distributed uniformly in the products. The as-prepared samples are composed of ~ 200 nm primary particles. Samples LiNi0.5 − xMn1.5 + xO4 (x = 0, 0.05, 0.1) are also tested to study the effects of different Ni/Mn ratios. Sample LiNi0.5Mn1.5O4 delivers discharge capacities of 130 mAh g−1 at 0.2 C. The decreasing of Ni/Mn ratio in samples reduces specific capacity. With the decreasing of Ni/Mn ratios in spinel, amount of Mn3+ are increased. Attributed to its high Mn3+ contents, sample LiNi0.4Mn1.6O4 delivers the highest discharge capacity of 106 mAh g−1 at a large current density of 15 C, keeping 84.5% of that at 0.2 C rate. With the increasing of Ni/Mn ratios in spinel, cycling performance is improved. Sample LiNi0.5Mn1.5O4 shows the best cycling stability, keeping 94.4% and 90.4% of the highest discharge capacities after 500 cycles at 1 C and 1000 cycles at 5 C.

Preparation and Characterization of Rice Husks-Derived Silicon-Tin/Nitrogen-Doped Reduced Graphene Oxide Nanocomposites as Anode Materials for Lithium-Ion Batteries

Silicon (Si) and Tin (Sn) are promising materials for anodes in lithium-ion batteries due to their high theoretical capacity and abundance of Si on earth. Si can be derived from rice husk which is the main agricultural byproduct in Thailand. However, the challenge of using these materials in lithium-ion batteries is the large volume expansion during charge-discharge process which leads to pulverization of electrodes. The effective solution is to combine these metals as composite with carbon supporter. Nitrogen-doped reduced graphene oxide (NrGO) has been used as carbon supporter in this research because of its high surface area, electrical conductivity and rate of electron transfer. To confirm phases of products, X-rays diffraction techniques (XRD) was measured. The results show that there were peaks of Si, Sn and carbon in XRD patterns. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to illustrate the morphology of prepared composites. From SEM and TEM results, there were small-sized particles of Si and Sn dispersed randomly on NrGO sheets. Furthermore, electrochemical properties of these products were measured to confirm their efficiency as anode materials in lithium-ion batteries by coin cell assembly. The prepared composite can deliver the highest initial capacity of 1600 mA h g-1 and expected to use as anode materials in the next generation lithium-ion batteries.

Carbon-Coated Ordered Mesoporous SnO₂ Composite Based Anode Material for High Performance Lithium-Ion Batteries.

Recently, tin oxide (SnO2) has received significant attention for use as an anode material for next generation lithium-ion batteries (LIBs) owing to its high theoretical capacity (782 mAh g-1), which is more than twice of that of the commercialized graphite (372 mAh g-1). Several additional advantages, such as low cost, environmental friendliness, easy fabrication and natural abundance improve its promise. Although the theoretical capacity of SnO2 is high, volume expansion during cycling causes issue with cycling stability. In this study, an ordered mesoporous SnO2 was synthesized using a hard template (SBA-15), such that its mesoporous structure can buffer SnO2 particles from cracks caused by volume expansion. It can also allow effective electrolyte infiltration to ensure better reactivity of the active material with Li+ ions. The capacity of synthesized mesoporous SnO2 improved to 218.4 mAh g-1 compared regular SnO2 nanoparticles (69.6 mAh g-1) after 50 cycles at a rate of 0.1 C. Furthermore, carbon-coated mesoporous SnO2 enhanced capacity retention upon cycling (844.6 mAh g-1 after 50 cycles at 0.1 C) by insulating and preventing the cracking of the active material during lithiation and delithiation.

Hierarchical C/SiOx/TiO2 ultrathin nanobelts as anode materials for advanced lithium ion batteries

TiO2-based nanomaterials are demonstrated to be a promising candidate for next generation lithium ion batteries due to their stable performance and easy preparation. However, their inherent low capacity impedes their wide application compared to commercial carbon nanomaterials. Here we present a unique in situ grafting-graphitization method to achieve a ternary nanocomposite of C/SiOx/TiO2 ultrathin nanobelts with a core–shell heterostructure. The obtained ternary nanocomposite integrates the merits of high specific capacity of SiOx, the excellent mechanical stability of graphite-like carbon and the high reactivity of TiO2. Cyclic voltammetric curves and cycling performance manifest the optimal ternary nanocomposite and deliver a very high initial specific capacity of ∼1196 mA h g−1 with both good rate capability (∼200 mA h g−1 up to 10 C) and especially enhanced cycle stability. Our work demonstrates that building hierarchical core–shell heterostructures is an effective strategy to improve capacity and cycling performance in other composite anodes for electrochemical energy storage materials.

Direct Synthesis of Nanotubular Si-TiO2for Lithium-Ion Batteries Anodes By Anodizing

Industry and the scientific community have been concentrating efforts on the production and development of energy storage systems ESS [1].By the energy density improvements of lithium ion battery electrodes for electronic devices (EDs) and energy vehicles (EVs), and cost of manufacturing must be taken into account, so that new developed materials can with the currently used batteries[2-4].Silicon is an important candidate as anode material for the next generation of lithium ion batteries(LIBs) because of its extremely high specific capacity (4200 mAh/g). However, Si particles degrade during the volumetric change related to lithiation/delithiation processes.Efforts have been made in the last decade in an attempt to minimize the instabilities caused by the large volumetric variation [5,6]. The most effective approaches in this regard include: (a) reduction of particle size to the nanometer size range to lower mechanical stress, (b) formation of a porous structure promoting a stable solid electrolyte interface SEI (c) dispersing Si nanoparticles in a conductive matrix to accommodate the volumetric variations and preserve the mechanical integrity of the electrode, (d) formation of amorphous SiO2 structure in small dimensions, and the(e) formation of intermetallic composite with structure layers to accommodate Si particles[7]. In the other hand, TiO2also incorporates Li(330 mAh/g)and shows a fast lithium intercalation reaction, without major volumetric effects during Li intercalation/deintercalation. In this work the aim is to produce Si nanoparticles embedded in a nanotubular TiO2 matrix, avoiding mechanical stress problems, due to volumetric changes and the formation of SEI directly between Si nanoparticles(SiNP) and the electrolyte. For this, Ti-Si alloys with 2 and 4 at.%Si were prepared by arc melting in an Ar atmosphere. A Si-Ti solid solution phase was obtained by furnace heating to 1200 ºC and rapidly cooling to a hard martensitic phase.Thin sheets of these alloys were cut and anodized in different electrolytes aiming to avoid the dissolution of the Si Particles. The structure and morphology of the Si rich TiO2 nanotubes were investigated by TEM, XPS, SEMand GID/DRX. Cell voltage transients of the anodizing of Ti2Si and Ti4Si indicate different levels of SiNP accumulation. Different electrolyte compositions, organic and inorganic, with and without fluoride were used for the growth of the porous structures. The effect of lithium addition on electrolytes is observed in favor of porous structure. SiNPs embedded in TiO2 were observed by SEM, TEM and characterized by GID/DRX.1% at. Si was measured by EDS onregular tubular TiO2 detached from Ti-2 at.%Si anodized in a fluoride based electrolyte, indicating that around 50% of the Si was not lost to the electrolyte during anodization. In the other hand, metallic Si phase was detected by grazing angle diffraction indicating that Si NP are formed. The developed process shows to be an efficient way for the direct fabrication of self-organized titania nanotubes containing silicon nanoparticles. [1]S.Goriparti, E.Miele, F. De Angelis, E. Di Fabrizio, R. P.Zaccaria, C. Capiglia, Journal of Power Sources, 257 (2014) 421-443. [2]Naoki Nitta, Feixiang Wu, Jung Tae Lee and GlebYushin. Materials Today Volume 18, Number 5 June (2015) [3] Peter G. Bruce, Bruno Scrosati, Jean-Marie TarasconAngewandteChemieAngew. Chem. Int. Ed. (2008), 47, 2930 – 2946 [4] Bruno Scrosati, Jürgen Garche, Lithium batteries: Status, prospects and future, Journal of Power Sources 195 (2010) 2419–2430 [5] Weitian Lia,1, Xianwei Guoa,1, YueLub, Lin Wanga, Ailing Fana, ManlingSuib, HaijunYua, Amorphous nanosized silicon with hierarchically porous structure for highperformance lithium ion batteries. Energy Storage Materials 7 (2017) 203–208 [6] Lucie Leveau , Barbara Laïk , Jean-Pierre Pereira-Ramos, AurelienGohier , Pierre Tran-Van ,Costel-SorinCojocaru. Silicon nano-trees as high areal capacity anodes for lithium-ion batteriesJournal of Power Sources 316 (2016) 1-7. [7] HuajunTian, FengxiaXin, Xiaoliang Wang, Wei He ,Weiqiang HanHigh capacity group-IV elements (Si, Ge, Sn) based anodes for lithium-ion batteries. Journal of Materiomics 1 (2015) 153-169 Figure 1

In-Situ AFM Measurements on Lithium Metal Anodes

Using lithium metal electrode for the next generation of Lithium Ion Batteries (LIB) possesses the advantage of high energy around 300 Wh/kg coupled with progressed cathode material [1]. However, the formation of lithium dendrites and mossy lithium under electrochemical load (cycling) are currently the major hindrance of a wider use of such material and commercialization of the concept. Recently, the aforementioned challenges have been analyzed by means of nuclear magnetic resonance and found [2]. Those formations lead to degradation processes which are not yet understood at the micro- and nanometer scale. Therefore, experiments with high spatial resolution under realistic conditions gaining a better understanding of such phenomena are of utmost importance. Based on the practical significance for various applications the in-situ atomic force microscopy (AFM) characterization under electrochemical load is a key to develop new devices with improved functionality. Within this contribution we present combined atomic force microscopy and cyclic voltammetry (CV) measurements of the electrode-electrolyte interface between lithium anode and LP 30 (LiPF6 in EC/DMC), a common electrolyte in conventional energy storage. Therefore, the simultaneous investigation of structural, electrochemical and mechanical properties under electrochemical conditions is demonstrated. We will discuss the formation of mossy lithium as well as the formation of dendrites within the in-situ AFM results. Our results shed light onto the small scale processes on lithium metal anodes for LIBs and path the way towards applicability of bare lithium as anode material.

Improvement of High Rate Performance of a Lithium Ion Battery Composed of Laminated LiFePO4 Cathodes/ Graphite Anodes with Porous Electrode Structure Fabricated with a Pico-Second Pulsed Laser

Development of lithium ion batteries (LIBs) helps promote the spread of electric vehicles (EVs) over the world. Everyone is expected that the next generation of eco-friendly and high-performance EVs that was driven with LIBs become very popular in our daily life in the future. However, it will take a long time before it becomes widespread because of two reasons; the performance of the electric vehicles cannot satisfy the demands of daily life, and LIBs are expensive. The achievement of charging and discharging with high current densities is one of the requirements for high performance LIBs in EVs, almost all of LIBs cannot satisfy the requirement specification (high rate performance) for the next generation of LIBs. When the present LIBs are charged and discharged with high current densities to shorten the charging time and to accelerate the EVs in shorter time, respectively, the charging and discharging capacities largely drop, and the rechargeable performance is seriously damaged. In order to improve the high rate performance of the present LIBs, selection of materials, optimization of cathode and anode particle sizes, composition of cathode and anode layers for active materials, binder and conductive additives, coating of the active material surfaces and design of cells and electrodes have been examined. Each examination has achieved some success in the point view of high rate performance. However, recently, improvement of the high rate performance in the present LIBs unfortunately reaches a deadlock. Therefore, in this study, we propose strongly one of the solutions for the improvement of high rate performance with our developed laser technology. In this study, we developed preparing a porous graphite anode and a lithium iron phosphate (LiFePO4, LFP) cathode with a pico-second pulsed laser, in which through-holes having 20 mm diameters and an opening rate of 0.5% were formed on the graphite layer/copper (Cu) anode and the LiFePO4 layer/aluminum (Al) cathode. The cells composed of porous cathodes and anodes exhibited improvement of the high rate discharging performance when compared with those of cells prepared with non-porous cathodes and anodes and with cells prepared with cathodes and anodes prepared with conventional porous current collectors. The formation of holes on the anodes and cathodes can be prepared simply and speedily with the pico-second pulsed laser to increase the accessibility of the anode and cathode materials to Li+, resulting in the enhancement of the rate performance of the electrodes. The mechanism of the improvement of the high rate discharging performance was discussed with the results of electrochemical impedance spectroscopy (EIS).

Dual Coatings, Triple the Benefit: A Study in ALD Surface-Modifications to Nickel-Rich Architectures

NMC 811 has elicited great attention as a high energy cathode material for next generation lithium ion batteries. With 80% Ni content, NMC 811 has surpassed energy densities of previous generations of NMC cathodes. However, there exist inherent drawbacks to increasing nickel content, which limit the long-term cell performance. As compared to structurally similar NMCs, 811 suffers from poor cycle life and decreased stability due to the surface reactivity of now heightened nickel in the fully oxidized state. A number of surface-modification methods have been adopted to address these significant degradation issues including atomic layer deposition (ALD). ALD is a platform technology that has been widely demonstrated throughout the literature to impart significant processing and performance gains on lithium ion battery technologies, having notable impacts on surface stabilization of the positive electrode. In this work we will explore ALD as a means of controlling surface phenomena in cell architectures containing NMC 811, and present evidence for improved performance under high voltage conditions. In addition, we will demonstrate the synergistic effects of dually coated cells with significant enhancement resulting upon pairing ALD-enhanced 811 with surface-modified natural graphite. Alongside observations of high voltage stability, ALD-modified cells exhibit upwards of 30% increased cycle life and superior rate capabilities, increasing the attractiveness of this material for next generation LIBs.

Lithium –Manganese Rich Li1.2Mn0.55Ni0.15Co0.1O2 (LMR-NMC) Based Cathodes for High Energy Density Lithium-Ion Batteries

The next generation lithium ion batteries (LIBs) will have almost the double the energy density (235 Wh kg-1) of the currently available LIBs based on lithium transition metal (TM) oxides, olivine cathodes and graphite or silicon anodes for electric vehicles [1]. The batteries should have also reduced cost, improved safety and cycle life. Lithium and manganese rich TM oxide composite cathodes given by the generic formula, xLi2MnO3. (1-x)LiMO2 (Li1.2Mn0.55Ni0.15Co0.1O2, LMR-NMC) that has almost double the capacity (~ 300 mAhg-1) of layered TM oxides, but needs to be electrochemically cycled to a voltage > 4.4V to achieve this high capacity. The high capacity is achieved by activation of Li2MnO3 component by charging above 4.4 V forming Li2O and MnO2 [2-5]. This contributes to the high irreversible capacities >25% for LMR-NMC electrodes and capacity fade due to significant reduction of electrolytes and electrode conductivity [3]. The capacity fade also associated with Mn dissolution from the host structure upon continuous-s high voltage cycling. Besides, the electrochemical stability of carbonate based electrolyte with LiPF6 salt will be serious concern that can sustain high voltage cycling (above 4.5V). During high voltage cycling >4.4 V LMR-NMC undergoes a structural transition from layered to the spinel phase resulting significant loss of energy.During cycling, practical energy density of LMR-NMC cathodes are reduced from 1000 Wh kg-1 during initial cycles to ~750 Wh kg-1 during 100th cycle which makes LMR-NMC practically impracticable. The structural transition to the spinel phase is an intrinsic phenomena associated with transition metal ions migrate to the lithium layer during high voltage cycling. The interfacial instability can be minimized by surface coatings such as metal oxides such as Al2O3, ZrO2, TiO2 etc., metal phosphate coatings such as AlPO4, LiFePO4 etc. blending with another cathode material. In this work, to overcome the issues of interfacial instability (to improve cycle life, C rate performance, irreversible capacity and energy loss, we present a method of LiF coating on to LMR-NMC which stabilizes interface and decreases the voltage fade [4]. In this approach, some of the M-O bonds are replaced by M-F bonds on the surface. The M-F bond is stronger and stabilizes the interphase during cycling. Partially, O2- is replaced by F- on the surface of LMR NMC and due to which the average oxidation state of the surface metal ions is slightly decreased which lead to decrease in charge potential thus minimizing the electrolyte decomposition and delivering better electrochemical performance. The fluorine doped cathodes deliver high capacity of ~300 mAh g-1 at C/10 rate (10-20% greater than the pristine LMR NMC cathodes), have high discharge voltage plateau (> 0.25V ) and low charge voltage plateau (0.2 to 0.4V) compared to pristine LMR NMC cathodes. Beside fluorine doping, improved interfacial stability and reduce voltage decay can be achieved through both cation and anion dopings. By cation doping Mn or Ni or Co with cations such as Mg, voltage fade has been significantly improved due to structural stabilization. As discussed above, F-substitution stabilizes the surface, helps to reduce charging voltage which is beneficial for LMR-NMC to obtain high capacity at low voltages without electrolyte additives [5]. Further substituting Ni2+ with Mg2+ helps in minimizing the cation migration as it blocks the tetrahedral void through which movement of cations takes place from transitional metal layer to Li-layer reducing voltage decay. The synergistic effect of both magnesium and fluorine substitution ((Mg-0.02 mole and LiF to LMR-NMC 1:50 mol %) on electrochemical performance of LMR-NMC shows excellent discharge capacity of ~300 mAhg-1 at C/20 rate whereas pristine LMR-NMC shows the initial capacity around 250 mAhg-1 in the voltage range between 2.5 and 4.7 V [5]. Mg-F doped LMR-NMC shows lesser Ohmic and charge transfer resistance, cycles very well. The voltage decay which is the major issue of LMR-NMC is minimized in Mg-F doped LMR-NMC compared to pristine and F-LMR -NMC. By addressing the voltage drop, LMR-NMC could be the new possible cathode material for next generation LIBs. ACKNOWLEDGMENT We acknowledge DST-SERB (Grant no. SB/FT/CS-147/2014) for the financial support for this work. REFERENCES 1. USABC Goals for Advanced Batteries for EVs - CY 2020 Commercialization http://uscar.org/guest/article_view.php?articles_id=852. M. M. Thackeray, C.Wolverton, E. D. Isaacs, Energy Environ. Sci., 5, 7854-7863 (2012). 3. S. K. Martha, J. Nanda, Y. Kim, R. Unocic, S. Pannala, N. J. Dudney, J. Mater. Chem. A., 1, 5587-5595 (2013). 4. S. Krishna Kumar, S. Ghosh, P. Ghoshal, S. K. Martha, J. Power Sources, 356, 115-123 (2017). 5. S. Krishna Kumar, S. Ghosh, S. K. Martha, Ionics 23, 1655–1662 (2017).

(Keynote) MnPO4-Coating for Improved Long-Term Performance of Li(Ni0.4Co0.2Mn0.4)O2 in Ionic Liquid-Based Electrolytes

MnPO4-coated LiNi0.4Co0.2Mn0.4O2 (MP-NCM) [1] is demonstrated to be a high performance lithium battery cathode material in combination with the room-temperature ionic liquid-based electrolyte consisting of LiTFSI-PYR14FSI (2:8 molar ratio). The MnPO4 coating acts as an ideal protective layer to physically prevent the contact between the NCM active material and the electrolyte, thus, successfully stabilizing the electrode/electrolyte interface and preventing detrimental side reactions even in conventional, carbonate-based electrolytes [2]. As a result, MP-NCM-based electrodes reveal greatly enhanced C rate capability and cycling stability – even under extreme conditions like extended operational potential windows, elevated temperature, and higher active material mass loadings. Employing an ionic liquid-based electrolyte allows for outstanding cycling stability of lab-scale pouch cells, offering a capacity retention of well above 85% after 2000 cycles. The superior electrochemical behavior of MP-NCM compared to as-synthesized NCM is assigned to the superior stability of the electrode/electrolyte interface and structural integrity when applying a MnPO4 coating, rendering this approach highly promising also for other state-of-the-art and next generation lithium battery cathodes.

Preparation and application of energy materials from biomass

Silicon-based anode materials in recent years has gained tremendous interest due to high theoretical specific capacity for next generation lithium ion battery. Some biomass, such as rice husks (RHs), has contained a lot of inorganic silicon, which are abundant in all the countryside and farmland. Considering that RHs are mainly composed of organic lignin, cellulose, hemicellulose, and inorganic Si compound, they could be used to prepare low-cost electrode materials, such as carbonaceous and silicon-based anode materials. In this work, we will present the synthesis of various anode materials from RHs with prominent performance for lithium ion battery application, such as porous C/SiO[Formula: see text] composites and Al-doped porous carbonized RHs husks composites.

Engineering Surface Vacancy to Stabilize High-Voltage Battery Cathodes

In this issue of Chem, Cao and co-workers report a stabilization strategy for high-voltage lithium-ion battery cathodes down to the atomic scale. Using LiNi0.5Mn1.5O4 as a model, the authors demonstrated a protocol for precisely modulating the interstitial lattice sites on the material surface, showing the promising capability to improve electrochemical cyclability.

Electrochemical Performance of Nano-SnO2 Anode with Carbonized Carbon Nanotubes Paper as Host

A 3-dimensional carbonized multi-walled carbon nanotube (MWCNT) paper was used as the host of nano-tin oxide (SnO2) for lithium-ion batteries (LIBs). The cellulose fibers were fully mixed with MWCNTs in water. Then, the paper was obtained via vacuum filtration. Carbonization was carried out in a vacuum furnace at 1460°C. SnO2 slurry was coated on the carbonized MWCNT paper (CMP). Scanning electron microscopy (SEM) was utilized to observe the anode electrode. The images of SEM indicated that the nano-SnO2 was embedded into the holes of the porous CMP collector. This contributed the increase of contact interface area of the nano-SnO2 and the collector and the significantly reduced interface resistance. Electrochemical tests showed that the initial discharge capacity reached 1745 mAh g−1 with a coulumbic efficiency (CE) of 70.39% at a current density of 50 mA g−1. The composite electrode still maintained a reversible capacity of 753 mAh g−1 with a CE of 98% at a current density of 200 mA g−1 after 100 cycles. These marvelous composite electrodes exhibited a promising future for the next generation of LIBs.

High‐Energy Aqueous Lithium Batteries

AbstractOwing to the high voltage of lithium‐ion batteries (LIBs), the dominating electrolyte is non‐aqueous. The idea of an aqueous rechargeable lithium battery (ARLB) dates back to 1994, but it had attracted little attention due to the narrow stable potential window of aqueous electrolytes, which results in low energy density. However, aqueous electrolytes were employed during the 2000s for the fundamental studies of electrode materials in the absence of side reactions such as the decomposition of organic species. The high solubility of lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) in water has introduced new opportunities for high‐voltage ARLBs. Nonetheless, these ideas are somehow overshadowed by the common perception about the essential limitation of the aqueous electrolyte. The electrochemical behaviour of conventional electrode materials can be substantially tuned in the water‐in‐salt electrolytes. The latest idea of utilising a graphite anode in the aqueous water‐in‐salt electrolytes has paved the way towards not only 4‐V ARLB but also a new generation of Li−S batteries with a higher operating voltage and energy efficiency. Furthermore, aqueous electrolytes can provide a cathodically stable environment for Li−O2 batteries. The present paper aims to highlight these emerging opportunities possibly leading to a new generation of LIBs, which can be substantially cheaper and safer.

ZnO/Cu2MgO3 hollow porous nanocage: A new class of hybrid anode material for advanced lithium-ion batteries

The lithium storage properties of hollow ZnO/Cu2MgO3 nanocages with porous outer shell as an efficient anode material for next generation lithium-ion battery (LIB) are demonstrated for the first time. The ZnO/Cu2MgO3 nanocages as anode material are synthesized by one-step cost-effective ultrasonic spray pyrolysis method. The porous outer shell with hollow interior not only offer ease of electrolyte diffusion and fast Li-ion transport, but also buffer the huge volume change during repeated lithiation/de-lithiation process. As a result, this novel anode demonstrates a high discharge capacity (441 mA h g-1 at the current density of 500 mA g−1 even after 400 cycles), excellent cycle stability, and outstanding rate capability.

Chemically polished lithium metal anode for high energy lithium metal batteries

The formation of lithium dendrites during operation is a major issue that has prevented the practical application of lithium metal anode, which is considered one of the most promising anode materials for next generation lithium batteries. The formation of dendrites has been attributed to the non-uniform and locally high current densities resulting from the uneven dissolution and deposition of lithium, which is associated with the topographical and electrical inhomogeneity on lithium foil. Herein, we demonstrate a facile chemical polishing strategy to remove the pristine film on lithium foil to simplify the surface chemistry of lithium and enable uniform lithium deposition/dissolution during cycles, which can then effectively improve the electrochemical performance of lithium metal batteries.

Controllable construction of flower-like FeS/Fe2O3 composite for lithium storage

Transitions metal sulfides/oxides have been considered as promising anode candidates for next generation lithium-ion batteries (LIBs) due to high theoretical capacities. However, the large volume change during lithiation/delithiation process and poor electronic conductivity often result in a poor charging/discharging performance. Herein, we design a flower-like FeS/Fe2O3 composite via a simple “solvothermal-oxidation” method, in which the Fe2O3 is most distributed on the surface of the flower. The unique porous structure and synergistic effect between FeS and Fe2O3 not only accommodate the large volume expansion, but also facilitate Li ion and electron transport. The Fe2O3 shell effectively reduce the dissolution of Li2Sx during discharge/charge process. When serving as the anode material in lithium ion battery, FeS/Fe2O3 exhibits superior specific capacity, rate capacity and cycling stability compared with pure FeS and Fe2O3.