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Lithium titanate (Li4Ti5O12, LTO) anode materials doped with Zr, Cr, and Co were prepared by a simple solution freeze-drying (SFD) strategy. Doping with Zr, Cr, and Co metal ions can reduce the charge transfer resistance and enhance the diffusion rate and conductivity of lithium ions. Among the prepared samples, LTO-0.1Zr shows the best electrochemical performance with the reversible capacities of 286.8, 258.5, 235.4, 196.2, 151.5, and 119.6 mAh g−1 at 0.5, 1, 2, 5, 10, and 20 C, respectively. After 500 cycles at 10 C, a high retention rate of 94.6% for LTO-0.1Zr capacity can still be achieved. As a result, this study provides a simple and effective way to improve the electrochemical performance of LTO as anode material for high rate lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Potassium-ion batteries (PIBs) are considered to be an alternative to lithium-ion batteries because of their more affordable manufacturing cost and lower potential (2.936 V compared to standard hydrogen electrodes). However, the large ionic radius and unstable structure of potassium ions have hindered their satisfactory electrochemical performance from being satisfactory. In this study, a layered SnS2@CQDs composite material was prepared using hydrothermal and pyrolysis methods as a promising anode material for PIBs. The composite material possessed a significant specific surface area, and the layered structure of SnS2 contributed to its unique potassium-ion intercalation/deintercalation properties. The anchoring of the CQDs and carbon coating restricted the volume effect of SnS2 and enhanced the electron transfer efficiency. PIBs prepared from this electrode exhibited a high potassium storage capacity (235 mA h g−1 after 120 cycles at 100 mA g−1) and excellent cycling stability (144.8 mA h g−1 after 500 cycles at 500 mA g−1). [ABSTRACT FROM AUTHOR]

With the shortage of lithium resources caused by the development of lithium-ion batteries, sodium-ion batteries have attracted research interest. Vanadium diselenide (VSe2), a transition metal disulfide compound with large layer spacing, is very promising to be utilized in sodium-ion batteries. However, the material suffers from great volume changes and disordered stacking agglomeration during battery charging and discharging, which brings bad effects on its electrochemical performance. For this reason, the nitrogen-fluorine co-doped three-dimensional carbon framework embedded VSe2 nanosheet (VSe2@3D-CNF) material was prepared by high-energy ball milling method. The three-dimensional carbon framework structure can well alleviate the volume expansion caused by charging and discharging, while avoiding the problem of no stacking of VSe2 during charging and discharging, which is beneficial to improve the stability of the electrode material, and the N and F double doping can increase the active sites and improve the electron transfer rate. The results show that the reversible capacity of VSe2@3D-CNF composite after 200 cycles at a current density of 200 mA g−1 is 447.3 mAh g−1, and the Coulomb efficiency is 99.32%. The rate capacities are 522.4, 465, 433.9, 403.4, 367.7, and 283.6 mAh g−1 at current densities of 0.1, 0.2, 0.3, 0.5, 1, and 2 A g−1, and the long cycle performance was 335.5 mAh g−1 after 500 cycles at a high current density of 1 A g−1. The above results indicate that VSe2@3D-CNF composites are very promising for application in anode materials for SIBs. [ABSTRACT FROM AUTHOR]

The heterostructured arrangement of metal sulfide/oxide is of paramount importance in dictating the electrochemical characteristics of anode materials for lithium-ion batteries (LIBs). In this investigation, a synthesized composite material, integrating molybdenum disulfide (MoS2) and molybdenum dioxide (MoO2) intercalated within polyaniline (PANI) under hydrothermal conditions, was employed. Within the granulated MoO2-MoS2@PANI composite, PANI acts as an efficacious matrix, effectively mitigating the re-agglomeration and pulverization of MoS2-MoO2 during prolonged cycling processes. Concomitantly, the cooperative effects among the MoS2, MoO2, and PANI constituents manifest in copious active sites and shortened ion transport pathways. As an anode material for LIBs, the MoO2-MoS2@PANI sample exhibits exemplary cycling performance, delivering a remarkable capacity of 860 mAh g−1 even after enduring 500 cycles at a rate of 0.1 A g−1. Furthermore, when scrutinized in a sodium-ion battery (LIB) at a rate of 2 A g−1, it demonstrates exceptional cycling performance, retaining a capacity of 490 mAh g−1 even after 1000 cycles. [ABSTRACT FROM AUTHOR]

MXene is a novel two-dimensional (2D) material with high electronic conductivity and hydrophilicity. MXene's progress is hampered because of its poor theoretical capacity. Based on this, a simple hydrothermal method is used to evenly distribute SnO2 on two-dimensional Ti3C2Tx MXene flakes. The highly conductive Ti3C2Tx MXene provides an excellent channel for the fast transit of electrons and Li ions and buffers the volume changes of SnO2 during lithiation/delithiation by constraining SnO2 between MXene nanosheets. CNTs enable their structural integrity to be ensured. As a result, the nitrogen-doped SnO2/MXene/CNTs hybrid material exhibits outstanding lithium storage performance, including high capacity, stable cyclic performance (927.26 mAh g−1 at 100 mA g−1, with 99.82% capacity retention after 100 cycles), and great rate performance (462.3 mAh g−1 at 1 Ag−1), making it as a promising negative electrode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

The world's energy supply depends heavily on lithium-ion batteries due to the progressive depletion of non-renewable resources. The issue of raising the energy density of lithium-ion batteries must be addressed. We are all aware that the anode material is one area where lithium-ion batteries still have room for development. A new anode material, tin disulfide, not only has a high theoretical specific capacity (645 mAh g−1), but also allows the formation of different microstructures through variable growth rates. In this study, we created three-dimensional nano-spheres of SnS2 using solid-phase synthesis and then wrapped SnS2 and B4C in OUCNTs (SnS2/B4C@OUCNT) using hydrothermal synthesis. Ascribed to the synergy between the highly chemical active B4C and the conductive carbon network of the OUCNTs, SnS2/B4C@OUCNT (149 Ω) effectively overcomes the drawback of high impedance of pure SnS2 (307 Ω) while exhibiting high capacity and cyclic stability. After 100 cycles at a current density of 100 mA g−1, this material displayed good electrochemical properties as the anode for lithium-ion batteries, obtaining a reversible capacity of 1024.7 mAh g−1 and a coulombic efficiency of 98.01%. The discharge capacity is 854.7 mAh g−1 with a coulombic efficiency of 98.57% after 200 cycles at 1000 mA g−1. [ABSTRACT FROM AUTHOR]

In this work, we synthesized the SnO2–Ni-carbon nanotube (CNT) (SNC) composite anode material by hydrothermal and ball milling methods. In this ternary composite, Ni-doped SnO2 is firmly anchored on the few-walled CNTs. Nano-Ni doping prevents the coarsening of Sn, enhances the electron conductivity, and stabilizes the structure during the process of charging and discharging. In addition, the CNTs can effectively buffer the volume change of SnO2 and improve the conductivity as well as shorten the transport distances of electron and Li+. Accordingly, the SNC shows a large reversible capacity of 1245.7 mA h g–1 after 400 cycles at 0.2 A g–1. With a capacity of 1078.2 mA h g–1 after 850 cycles at 1.0 A g–1, it exhibits a long-term cycling stability. Meanwhile, the capacity can still reach 666.5 mA h g–1 at 5.0 A g–1 with excellent rate capability. The performance and stability of this Ni-doped composite are much better than those of SnO2, implying that SNC is exceedingly prospective as an anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Large capacity, high rate, and long-term cycling stabilities have always been pursued by lithium-ion batteries (LIBs). In this work, the straightforward hydrothermal and high-speed ball milling programs were employed to create the SnO2-NiO-C anode material. NiO nanoparticles with unique hexagonal crystal structure are an ideal choice for ion cycling and embedding, which can stabilize the structure and prevent SnO2 from becoming coarser. The graphite encapsulated in the outer layer can effectively prevent volume expansion during the cycling as well. From the research results, SnO2-NiO-C exhibits a significant reversible capacity of 1224.3 mAh g−1 after 300 cycles at 0.2 A g−1, and after the fourth cycle, the coulombic efficiency remains above 97%. And it also possesses a long-term cycling stability of 820.1 mAh g−1 after 1000 cycles at 1.0 A g−1. Also, a significant rate property can reach 507.1 mAh g−1 even at 5.0 A g−1. Therefore, the SnO2-NiO-C anode material for LIBs is promising because of its excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

Vanadium diselenide (VSe2), with large interlayer spacing, is a promising anode material for sodium-ion batteries (SIBs). However, due to the existence of a conversion reaction, VSe2 will encounter a huge volume change during charging/discharging, resulting in electrode pulverization. On the other hand, VSe2 nanosheets are prone to disordered stacking during the deintercalation of sodium ions, affecting the next intercalation. Therefore, VSe2 embedded into a three-dimensional N-doped carbon framework (VSe2@3D-CN), was constructed to solve the above problems. Firstly, the three-dimensional carbon framework, with void spaces, can maintain the structural integrity of the electrode during charging/discharging, improving cycle performance. Secondly, the structure that VSe2 nanosheets are embedded in a three-dimensional carbon framework can avoid disordered stacking for VSe2, which can maintain an open insertion channel of sodium ions. Thirdly, nitrogen doping can increase the active sites, enhancing the absorption of sodium ions in the carbon layer and thus obtaining superior rate performance. Based on the synergistic effect of the above modification strategies, outstanding electrochemical performance was obtained. After charging and discharging 150 times at a current density of 200 mA/g, the specific capacity of VSe2@3D-CN is up to 465 mAh/g. Besides, the sodium storage model of VSe2@3D-CN has been built via ex situ XPS and ex situ HRTEM tests, which provides an important reference for improving cycle performance. [ABSTRACT FROM AUTHOR]