Search

Secondary batteries have been widespread in the daily life causing an ever-growing demand for long-cycle lifespan and high-energy alkali-ion batteries. As an essential constituent part, electrode materials with superior electrochemical properties play a vital role in the battery systems. Here, an outstanding electrode of yolk-shell ZnS@C nanorods is developed, introducing considerable void space via a self-sacrificial template method. Such carbon encapsulated nanorods moderate integral electronic conductivity, thus ensuring rapid alkali-ions/electrons transporting. Furthermore, the porous structure of these nanorods endows enough void space to mitigate volume stress caused by the insertion/extraction of alkali-ions. Due to the unique structure, these yolk-shell ZnS@C nanorods achieve superior rate performance and cycling performance (740 mAh g-1 at 1.0 A g-1 after 540 cycles) for lithium-ion batteries. As a potassium-ion batteries anode, they achieve an ultra-long lifespan delivering 211.1 mAh g-1 at 1.0 A g-1 after 5700 cycles. The kinetic analysis reveals that these ZnS@C nanorods with considerable pseudocapacitive contribution benefit the fast lithiation/delithiation. Detailed transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses indicate that such yolk-shell ZnS@C anode is a typical reversible conversion reaction mechanism accomplished by alloying processes. This rational design strategy opens a window for the development of superior energy storage materials. [ABSTRACT FROM AUTHOR]

For the past few years, a new generation of energy storage systems with large theoretical specific capacity has been urgently needed because of the rapid development of society. Lithium–sulfur (Li−S) batteries are regarded as one of the most promising candidates for novel battery systems, since their resurgence at the end of the 20th century Li−S batteries have attracted ever more attention, attributed to their notably high theoretical energy density of 2600 W h kg−1, which is almost five times larger than that of commercial lithium‐ion batteries (LIBs). One of the determining factors in Li−S batteries is how to design/prepare the sulfur cathode. For the sulfur host, the major technical challenge is avoiding the shuttling effect that is caused by soluble polysulfides during the reaction. In past decades, though the sulfur cathode has developed greatly, there are still some enormous challenges to be conquered, such as low utilization of S, rapid decay of capacity, and poor cycle life. This article spotlights the recent progress and foremost findings in improving the performance of Li−S batteries by employing multifunctional metal phosphides as host materials. The current state of development of the sulfur electrode of Li−S batteries is summarized by emphasizing the relationship between the essential properties of metal phosphide‐based hybrid nanomaterials, the chemical reaction with lithium polysulfides and the latter′s influence on electrochemical performance. Finally, trends in the development and practical application of Li−S batteries are also pointed out. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) are the most promising candidates as alternatives to lithium‐ion batteries (LIBs), owing to the natural abundance of sodium salt and the low cost. However, the commercial application of SIBs is principally hampered by the absence of suitable cathode materials. Herein, a novel Na2FeP2O7@carbon/expanded graphite (NFPO@C/EG) composite with a unique microstructure was developed through a scalable sol‐gel process followed by a ball‐milling procedure with expanded graphite. Benefiting from the multiscale carbon‐modified structure, the NFPO@C/EG effectively improves the electronic conductivity and, at the same time, shortens the path of sodium ion transmission. As a consequence, the NFPO@C/EG cathode presents a much higher specific capacity and more stable cycling stability than NFPO@C and NFPO. The unique design of NFPO@C/EG endows a high ratio of pseudocapacitance contribution and a large Na+ diffusion coefficient. As a consequence, the NFPO@C/EG cathode displays stable cycle performance (82 mAh g−1 over 400 cycles at 232 mA g−1) and superior rate capability (60 mAh g−1 at a high charge/discharge density of 2320 mA g−1). This multiscale carbon‐modified design concept builds an avenue for the practical application of polyanionic cathode materials and promotes the development of low‐cost SIBs. [ABSTRACT FROM AUTHOR]

As anode materials for high‐performance Li‐ion batteries, peapod‐like Ge‐based composites, including Ge, a Li‐inactive conducting Cu3Ge, and a porous carbon matrix are synthesized simply by annealing CuGeO3@dopamine in a H2/Ar atmosphere. The introduction of the carbon layer and inactive alloying phase Cu3Ge not only enhances the electrical conductivity of the Ge anode, but also reduces the volume change of Ge during the cell cycle as a buffer. In particular, the anode of this peapod‐like Cu3Ge/Ge@C shows an excellent long cycle life as well as outstanding capacity performance, with a discharge specific capacity up to 934 mA h g−1 after 500 cycles. [ABSTRACT FROM AUTHOR]

Amorphous nanoparticles of ZnO and TiO2 embedded in carbon nanocages (AZT⊂CNCs) were successfully synthesized through a simple annealing process of TiO2‐coated zeolitic imidazolate framework‐8 (ZIF‐8). In the current anode of AZT⊂CNCs, tiny ZnO and TiO2 nanoparticles were uniformly distributed in the carbon matrix (carbon nanocages), which could effectively buffer the volume expansion of electroactive ZnO and provide excellent electric conductivity. After fully investigating the electrochemical performance of the AZT⊂CNCs samples obtained with different additive amounts of tetrabutyl orthotitanate (TBOT) for TiO2 coating, it has been found that AZT‐30 (0.1 g ZIF‐8 with 30 mL TBOT) shows the best cycle stability (510 mA h g−1 after 350 cycles at 200 mA g−1) and a superior rate capability (610 mA h g−1 after 3500 cycles at 2 A g−1). The greatly enhanced Li‐ion storage performance could be ascribed to the fact that the introduction of amorphous TiO2 could activate the reversible lithiation/delithiation reaction of ZnO during the charge/discharge process. Dramatically enhanced: Amorphous nanoparticles of ZnO and TiO2 embedded in carbon nanocages (AZT⊂CNCs) were successfully synthesized by a simple annealing process of TiO2‐coated ZIF‐8 (see figure). As a Li‐ion battery anode, the hollow structure and porous carbon matrix make these materials useful. Moreover, with the addition of TiO2, the electrochemical reactions of the ZnO anode are greatly activated. [ABSTRACT FROM AUTHOR]

Keywords: Li-ion batteries; high-energy density; sulfur; metal phosphides EN Li-ion batteries high-energy density sulfur metal phosphides 1 1 1 09/28/21 20210924 NES 210924 In addition to avoiding the shuttling caused by soluble polysulfides, the design and preparation of sulfur cathodes for Li-S batteries must overcome challenges such as the low use of S, rapid decay of capacity and poor cycle life. This review spotlights recent progress in improving the performance of Li-S batteries by employing multifunctional metal phosphides as host materials. Frontispiece: Multifunctional Metal Phosphides as Superior Host Materials for Advanced Lithium-Sulfur Batteries. [Extracted from the article]

The cathode, a crucial constituent part of Li-ion batteries, determines the output voltage and integral energy density of batteries to a great extent. Among them, Ni-rich LiNixCoyMnzO2 (x + y + z = 1, x ≥ 0.6) layered transition metal oxides possess a higher capacity and lower cost as compared to LiCoO2, which have stimulated widespread interests. However, the wide application of Ni-rich cathodes is seriously hampered by their poor diffusion dynamics and severe voltage drops. To moderate these problems, a nanobrick Ni-rich layered LiNi0.6Co0.2Mn0.2O2 cathode with a preferred orientation (110) facet was designed and successfully synthesized via a modified co-precipitation route. The galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) analysis of LiNi0.6Co0.2Mn0.2O2 reveal its superior kinetic performance endowing outstanding rate performance and long-term cycle stability, especially the voltage drop being as small as 67.7 mV at a current density of 0.5 C for 200 cycles. Due to its unique architecture, dramatically shortened ion/electron diffusion distance, and more unimpeded Li-ion transmission pathways, the current nanostructured LiNi0.6Co0.2Mn0.2O2 cathode enhances the Li-ion diffusion dynamics and suppresses the voltage drop, thus resulting in superior electrochemical performance. [ABSTRACT FROM AUTHOR]

N-doped carbon-encapsulated ZnSe@C with uniform core-shell nanorod structure has been successfully fabricated via a self-sacrificial template route. Due to the special porous nanorods structure, this ZnSe@C anode effectively moderates the volume expansion, improves the electron conductivity, and thus delivers a superior rate capability and stable cycling performance for KIBs. • Uniform core-shell ZnSe@C was synthesized via a facile self-sacrificial route. • Such ZnSe@C anode shows superior rate capability and cycling performance. • 1D carbon-encapsulated porous structure enhances the electrochemical performance. Potassium-ion batteries (KIBs) have now stimulated considerable attention due to the widely distributed potassium salt and low cost, which become the competitive candidate for Na-/Li-ion batteries and suitable application for large-scale energy systems. Here, we have reasonably designed N-doped carbon encapsulated yolk-shell ZnSe@C anode with carbon-coated Zn 2 GeO 4 @C nanorods as the self-sacrificial template. Uniform ZnSe@C nanorods were facilely prepared by the selenidation of carbon-coated Zn 2 GeO 4 @C nanorods, which were synthesized via a simple annealing of ploydopamine-coated Zn 2 GeO 4 nanorods. Such N-doped carbon encapsulated ZnSe@C core-shell nanorods could substantially enhance the electronic conductivity, moderate the volume expansion and provide more pathways for K+ diffusion. In detail, these ZnSe@C nanorods achieve stable galvanostatic discharge/charge performance (deliver 360 mA h g−1 at 0.2 A g−1 after 60 cycles and 204 mA h g−1 at 2.0 A g−1 over 100 repeated cycles) and superior rate capability (achieve a capacities of 389.4, 379.8, 352.2, 285.6, 226.1, and 167.5 mA h g−1 at 0.1, 0.2, 0.5, 1.0, 2.0, and 4.0 A g−1, respectively). The charge-discharge mechanism of ZnSe@C was further investigated by in-situ , ex-situ X-ray diffraction XRD and transmission electron microscopy (TEM) measurements. [ABSTRACT FROM AUTHOR]

• The Li 2 GeO 3 /EG was prepared by a simple, economical and easily scalable high-energy ball-milling method. • Li 2 GeO 3 particles were uniformly grown on EG nanosheets. • The EG coating can improve the electronic conductivity of Li 2 GeO 3. • The Li 2 GeO 3 /EG composite exhibits remarkably enhanced lithium storage performance. [Display omitted] A simple, economical, and easily scalable high-energy ball-milling method for the synthesis of Li 2 GeO 3 /expanded graphite (LGO/EG) as a high-performance anode for lithium-ion batteries is reported. The LGO/EG exhibits a unique architecture with expanded graphite (EG) uniformly coating Li 2 GeO 3 (LGO) particles, which effectively inhibited the agglomeration of LGO particles. The LGO/7 wt%EG anode delivers a discharge capacity of 800.6 mA h g−1 at 5.0 A g−1, with an outstanding capacity retention of 75.9% after 300 cycles at 1.0 A g−1, which is 8.3% higher than that of the uncoated LGO anode. This is attributed to the introduction of EG which improves the electronic conductivity of LGO, and the uniformly coated EG can effectively inhibit the volume change of LGO particles during the charging-discharging process. As a result, LGO/EG has outstanding high-rate performance and long-term cycle stability. [ABSTRACT FROM AUTHOR]