Xuejie Huang

A high capacity nano-Si composite anode material for lithium rechargeable batteries

A nano-Si composite material (NSCM) has been prepared by mixing nanometer-scale (78 nm) pure Si powder and carbon black. The electrochemical performance of NSCM anodes for lithium rechargeable batteries exhibited an extremely high reversible capacity, over 1700 mAh/g Si, at the tenth cycle. The voltage profile is flat and smooth ranged from 0.4 to 0.0 V vs. Li/Li+. In addition, the cyclic performance is good even at larger current densities. Consequently, NSCM can be used as a novel high capacity anode material for lithium-ion batteries

Monodispersed hard carbon spherules with uniform nanopores

Hard carbon with perfect spherical morphology was prepared for the first time by a hydrothermal method. It has controllable monodispersed particle size and a smooth surface. Transmission electron microscopy shows that there are a large quantity of uniform nanopores of about 0.4 nm in diameter and only very few parallel graphene sheets exist within the spherules. This hard carbon material has a specific BET surface area of 400 m2/g for N2 as adsorbate, and can reversibly store lithium up to 430 mAh/g. This shows convincingly that carbon nanopores can store a large quantity of lithium.

The crystal structural evolution of nano-Si anode caused by lithium insertion and extraction at room temperature

Abstract The crystal structure and morphology of nanosized Si particles and wires after Li-insertion/extraction electrochemically have been studied by ex-situ XRD, Raman spectroscopy and electronic microscopy. It is confirmed that the insertion of lithium ions at room temperature destroys the crystal structure of Si gradually and leads to the formation of metastable amorphous Li–Si alloy. Furthermore, local ordered structure of Si can be restored after the partial extraction of lithium ions, which indicates the extraction of lithium ions promoting the recrystallization of amorphous Li-inserted Si. It was also observed that nanosized Si particles and wires were merged together after the insertion/extraction of lithium ions.

A zero-strain layered metal oxide as the negative electrode for long-life sodium-ion batteries

Room-temperature sodium-ion batteries have shown great promise in large-scale energy storage applications for renewable energy and smart grid because of the abundant sodium resources and low cost. Although many interesting positive electrode materials with acceptable performance have been proposed, suitable negative electrode materials have not been identified and their development is quite challenging. Here we introduce a layered material, P2-Na0.66[Li0.22Ti0.78]O2, as the negative electrode, which exhibits only ~0.77% volume change during sodium insertion/extraction. The zero-strain characteristics ensure a potentially long cycle life. The electrode material also exhibits an average storage voltage of 0.75 V, a practical usable capacity of ca. 100 mAh g(-1), and an apparent Na(+) diffusion coefficient of 1 × 10(-10) cm(-2) s(-1) as well as the best cyclability for a negative electrode material in a half-cell reported to date. This contribution demonstrates that P2-Na0.66[Li0.22Ti0.78]O2 is a promising negative electrode material for the development of rechargeable long-life sodium-ion batteries.

Alumina-Coated Patterned Amorphous Silicon as the Anode for a Lithium-Ion Battery with High Coulombic Efficiency

A patterned silicon electrode as the anode of lithium ion batteries is fabricated by microfabrication technology. An ultrathin alumina layer is coated on the patterned electrode by atomic layer deposition (ALD). This results in obviously enhanced coulombic efficiency and cycling performance. [GRAPHICS] .

Structural and electrochemical characterizations of surface-modified LiCoO2 cathode materials for Li-ion batteries

Commercial LiCoO2 has been coated with metal oxides including MgO, Al2O3 and SnO2. The morphology and structure of the coating layer have been characterized with scanning electron microscope (SEM) and high-revolution transmission electron microscope (HRTEM). It is found that the coating layer is amorphous and rather compact. LiCoO2 coated with different metal oxides demonstrate different electrochemical performances. MgO-coated LiCoO2 cathode shows very good electrochemical stability up to a charge cutoff voltage of 4.7 V while Al2O3-coated LiCoO2 is electrochemically stable up to 4.5 V. However, SnO2-modified LiCoO2 is stable only at low-charge cutoff voltages. Cyclic voltammetry (CV) and charge–discharge cycling show that surface modification does not influence the phase transitions below 4.5 V but the phase transition at about 4.58 V is drastically suppressed. These improvements are attributed to the modifications to the surface property of the particles by coating and to the lattice structure of LiCoO2 during cycling.

Prototype Sodium‐Ion Batteries Using an Air‐Stable and Co/Ni‐Free O3‐Layered Metal Oxide Cathode

A prototype rechargeable sodium-ion battery using an O3-Na0.90[Cu0.22 Fe0.30 Mn0.48]O2 cathode and a hard carbon anode is demonstrated to show an energy density of 210 W h kg(-1) , a round-trip energy efficiency of 90%, a high rate capability (up to 6C rate), and excellent cycling stability.

Anodes based on oxide materials for lithium rechargeable batteries

A two-step reaction mechanism of oxide materials as anodes in rechargeable lithium batteries was found by comparing discharge–charge curves and cyclic voltammograms of eight oxides. It was also proved by experiments of ex-situ XRD of Sb2O3 anode at discharged state. HRTEM images of nanometre SnO at deep discharged state confirmed the two-step reaction mechanism and showed the typical microstructure character of reaction products: the particle was composed of a large amount of nanosized Li–Sn alloy which dispersed in the Li2O matrix. Furthermore, it was found that the electrochemical properties of SnO anodes were influenced by the particle size of SnO.

Amorphous monodispersed hard carbon micro-spherules derived from biomass as a high performance negative electrode material for sodium-ion batteries

Sodium-ion batteries (SIBs) are expected to be a promising commercial alternative to lithium-ion batteries (LIBs) for large-scale and low-cost electrical energy storage applications in the near future. Despite this, the absence of a suitable negative electrode material hinders their development. In this contribution, we synthesized monodispersed hard carbon spherules (HCS) from an abundant biomass of sucrose, and investigated the influence of the carbonization temperature on the microstructure and electrochemical performance. The initial coulombic efficiency of the HCS was increased to 83% by coating its surface with soft carbon through the pyrolysis of toluene. Interestingly, the plateau capacity at the low potential region increased with increasing carbonization temperature. The HCS carbonized at 1600 °C showed the highest plateau capacity (220 mA h g−1) and excellent cycling performance with a capacity retention of 93% after 100 cycles. When coupled with an air-stable P2-Na2/3Ni1/3Mn2/3O2 positive electrode, the full cell exhibited a high initial coulombic efficiency of 76%, a mean operating voltage of 3.5 V and excellent cycling performance. The theoretical energy density of this system was estimated to be 200 W h kg−1. These promising properties are believed to be close to the level required for practical applications.

Novel spherical microporous carbon as anode material for Li-ion batteries

Hard carbon spherules (HCS) with micropores were prepared by a hydrothermal method. It has perfect spherical morphology, controllable monodisperse particle size and smooth surface. XRD and Raman spectra show that HCS is nongraphitizable. The reversible capacity of HCS is about 430 mA h/g in using as anode material for lithium ion batteries, and the cyclic performance of HCS is excellent. The kinetic characteristics of HCS are better than MCMB. In addition, the Coulombic efficiency of HCS has been improved by surface modifications such as CVD of acetylene and coating of tetraethoxysilane (TEOS) on the surface of HCS. Furthermore, pinning of the nanosized SnSb alloy particles on the surface of HCS hinders the electrochemical aggregation of alloy particles effectively during charge/discharge cycles. Consequently, the cyclic performance and reversible capacity are much enhanced.