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Zero-valent antimony and antimony oxide were deposited on graphene oxide by the recently introduced peroxide deposition route. The antimony@graphene oxide (GO) anode exhibits a charging capacity of 340 mAh g-1 with excellent stability at a current rate of 250 mA g-1 after 50 cycles of lithiation, which is superior to all other forms of antimony anodes that have been reported thus far. The electrode also exhibits a good rate performance, with a capacity of 230 and 180 mAh g-1 at a rate of 500 and 1000 mA g-1, respectively. We attribute the superior performance of the antimony@GO anodes to our coating protocol, which provides a thin layer of nanometric antimony coating on the graphene oxide, and to a small amount of antimony oxide that is left in the anode material after heat treatment and imparts some flexibility. The efficient charge distribution by the large surface area of reduced GO and the expansion buffering of the elastic graphene sheets also contributed to the superior stability of the anode.

Abstract: Co3O4 nanoparticles are grown on nitrogen modified microwave exfoliated graphite oxide (NMEG) with weight ratio controlled from 10% to 70%. Electrochemical performance reveals that the obtained Co3O4/NMEG composite as Li-ion battery anode exhibits improved cycle stability, excellent reversible capacity, high current rate performance, and reduced irreversible capacity loss in the initial cycle compared to pure Co3O4 without graphene or Co3O4 on thermally reduced graphene oxide (tRG-O). The 70%Co3O4/NMEG composite has initial irreversible capacity of 230mAhg−1 (first cycle efficiency of 77%), and 910mAhg−1 of capacity is retained after 100 cycles. The 70%Co3O4/tRG-O delivers a reversible capacity of 750±20mAhg−1, and the irreversible capacity loss during the first cycle is 700±20mAhg−1. Nitrogen functional groups in NMEG, especially pyridinic and pyrrolic N are advantageous for the Co3O4 growth. Furthermore, the N modification is effective in reducing the oxygen content of chemically prepared graphene and hence is good for Co3O4 dispersion and the amelioration of first cycle efficiency, demonstrating the potential of NMEG based composite as high performance Li-ion battery anode materials. [Copyright &y& Elsevier]

High-Ni materials LiNiO 2 or LiNi 1-x M x O 2 (x < 0.1), whose energy density is over 800 Wh kg−1 (discharge capacity >220 mAh g−1, average discharge voltage ∼3.8 V), are promising candidates as cathode for next-generation electric vehicle batteries. However, commercial applications of high-Ni cathodes have been hindered by their fast capacity fading with cycling. Herein, we synthesized a series of high-Ni materials (LiNiO 2 , LiNi 0.95 Co 0.05 O 2 and LiNi 0.9 Co 0.1 O 2) by adopting nanosheet hydroxide precursors. The obtained high-Ni materials with micro-spheres made up of nanorod grains can sustain the large volume deformation and eliminates cracking during charge-discharge. Owing to the hierarchical structure, our as-synthesized high-Ni cathodes exhibit excellent cycling stability up to 4.7 V and under high temperatures, and the corresponding full cells show superior long cycling stability suitable for practical applications, such as 94% and 83% capacity retention after 300 and 500 cycles, respectively for a LiNi 0.95 Co 0.05 O 2 ||graphite cell. Overall, this study offers a facile approach to address the poor cycling stability of high-Ni materials. Nanosizing the primary crystals of high-Ni cathode materials (LiNi 1-x M x O 2 , x < 0.1) can eliminate particle pulverization, and nanorods are more effective than ultra-fine nanocrystals in suppressing cracking. The nanorods in pure or Co-doped LiNiO 2 can be directly synthesized from nanosheet hydroxide precursors. [Display omitted] • High Ni nanosheet hydroxide precursors were synthesized. • Corresponding LiNiO 2 and LiNi 0.95 Co 0.05 O 2 adopt spherical particles with nanorods. • Nanorods LiNiO 2 and LiNi 0.95 Co 0.05 O 2 cathodes exhibit excellent cycle stability. • Cycle stability maintained at high voltage and high temperature. • Nanorod grains accommodate lattice stress and suppress particle cracking. [ABSTRACT FROM AUTHOR]

Electrode cracking is a serious problem that hinders the application of many next-generation high-capacity anode materials for lithium-ion batteries. Even though nano-sizing the material can reduce fracturing of individual particles, capacity fading is still observed due to large volume change and loss of contact in the electrode during lithium insertion and extraction. In this study, we design a crack-resistant high-modulus polyimide coating with high compressive strength which can hold multiple particles together during charge and discharge to maintain contact. The effectiveness of the coating is demonstrated on tin dioxide, a high-capacity large-volume-change material that undergoes both alloy and conversion reactions. The polyimide coating improves capacity retention of SnO 2 from 80% to 100% after 80 cycles at 250 mA g −1 . Stable capacity of 585 mAh g −1 can be obtained even at 500 mA g −1 after 300 cycles. Scanning electron microscopy and in-situ dilatometry confirm that electrode cracking is suppressed and thickness change is reduced with the coating. In addition, the chemically-stable polyimide film can separate the surface from direct contact with electrolyte, improving coulombic efficiency to ∼100%. We expect the novel strategy of suppressing electrode degradation with a crack-resistant coating can also be used for other alloy and conversion-based anodes. [ABSTRACT FROM AUTHOR]

Layered monoclinic LiMnO 2 is a potential low-cost alternative to LiCoO 2 cathode for lithium-ion batteries. However, its application is limited partly because it cannot be synthesized easily. In this work, we successfully synthesized phase-pure layered LiMnO 2 in a one-step low-temperature process using electrolytic manganese dioxide (EMD) as the manganese precursor at 450 °C in Ar atmosphere by a carbothermal reduction method. The initial carbon to manganese ratio has to be optimized to remove impurities. The particle size of the material is between 40 and 60 nm. The synthesized sample shows an initial reversible capacity of about 180 mAh g −1 . The synthesis method is further applied to make boron-doped samples, which significantly enhanced the stability of the material, especially at high temperature. The boron-doped samples maintain a capacity of 150 mAh g −1 for 100 cycles and give a capacity of about 100 mAh g −1 at a current of 1000 mA g −1 (equivalent to 10C rate). The ability to directly synthesize the material at low temperature is crucial because it allows further improvement of material performances through methods such as surface coating and the use of electrolyte additives to reduce surface reaction and Mn-dissolution. [ABSTRACT FROM AUTHOR]

Thermal stability of a lithium-rich layered oxide cathode material with composition 0.5Li 4/3 Mn 2/3 O 2 –0.5LiNi 1/3 Co 1/3 Mn 1/3 O 2 (LMO–NCM) is investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Investigated material shows higher thermal stability (higher onset temperature) than LiCoO 2 . The state of charge and previous cycling history of LMO–NCM, particularly activation of lithium manganese oxide (LMO) “component” during first charge, affect its thermal stability. Activation of LMO has an ambivalent effect on cathode thermal stability: on the one hand, the onset temperature of cathode decomposition is increased, probably due to the change in oxidation states of Ni, Co and Mn after the first cycle. On the other hand, the enthalpy of decomposition increases, presumably due to formation of unstable oxygen in the lattice. X-ray diffraction (XRD) analyses of cathodes before and after thermal decomposition at 600 °C indicate differences in decomposition reactions of charged cathodes, depending on state of charge and cycling history. [ABSTRACT FROM AUTHOR]

Abstract: Thermal stability of charged LiCoO2 cathodes with various surface areas of active material is investigated in order to quantify the effect of LiCoO2 surface area on thermal stability of cathode. Thermogravimetric analyses and calorimetry have been conducted on charged cathodes with different active material surface areas. Besides reduced thermal stability, high surface area also changes the active material decomposition reaction and induces side reactions with additives. Thermal analyses of LiCoO2 delithiated chemically without any additives or with a single additive have been conducted to elaborate the effect of particle size on side reactions. Stability of cathode–electrolyte system has been investigated by accelerating rate calorimetry (ARC). Arrhenius activation energy of cathode decomposition has been calculated as function of conversion at different surface area of active material. [Copyright &y& Elsevier]

Silicon monoxide (SiO) is a promising anode material for Li-ion batteries because of its high capacity. Though, its low first Coulombic efficiency (FCE) due to the formation of inactive Li–Si–O compounds during lithiation hinders its practical application. Herein, we report a facile pre-sodiation technique by annealing SiO with a small amount of Na 2 CO 3 (≤ 5 wt%) under 850 °C, which improves FCE of pristine SiO from 61.4% to 86.0% without the use of lithium metal, solvent and disassembling and re-assembling of cells. Transmission electron microscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance demonstrate that the incorporation of Na facilitates the disproportionation of SiO into crystalline Si and SiO 2 through nucleophilic substitution, and reduces the reactivity of the oxygen atoms with lithium and thereby suppresses the irreversible capacity during initial lithiation. The pre-sodiation process also improves thermal stability of SiO. Since the Na-containing SiO material is not sensitive to moisture in ambient condition, special handling of the material is not necessary. Combining with a LiFePO 4 cathode, the full cell shows a FCE of 85.8% with good cycle stability. The energy density of lithium-ion battery can even reach 900 Wh L−1 based on a theoretical calculation with high-capacity Ni-based metal-oxide cathode. • First Coulombic efficiency of SiO is increased to 86% by heat-treating with Na 2 CO 3. • Na 2 CO 3 facilitates disproportionation of SiO to SiO 2 , inactivating the oxygen atoms in the lattice. • Thermal stability of pre-treated SiO is enhanced with less heat generation. • The treated material is stable in air and exhibits remarkable water compatibility. • A LIB with volumetric energy density of 900 Wh L−1 can be achieved with optimization. [ABSTRACT FROM AUTHOR]