Jia-Ying Liao

In situ catalytic formation of graphene decoration on Na3V2(PO4)3 particles for ultrafast and long-life sodium storage

Graphene-decorated Na3V2(PO4)3 (NVP@G) material is synthesized through an in situ catalytic process using the intermediate product component VOx as a catalyst and polyvinyl alcohol as the graphene source. NVP@G shows a superb rate performance and an ultralong cycle life.

A potassium-rich iron hexacyanoferrate/dipotassium terephthalate@carbon nanotube composite used for K-ion full-cells with an optimized electrolyte

K-ion batteries, as an emerging battery system, have attracted tremendous attention in the research community. Herein, we report a K-ion full-cell based on a nano-sized K1.92Fe[Fe(CN)6]0.94·0.5H2O cathode, dipotassium terephthalate (K2TP)@carbon nanotube (CNT) anode and an optimized electrolyte. K1.92Fe[Fe(CN)6]0.94·0.5H2O delivers a high capacity of 133 mA h g−1 with 92.8% capacity retention after 200 cycles and high coulombic efficiency of 98.5%. The side reactions of K metal with the electrolyte are suppressed in KClO4/propylene carbonate (PC). The K2TP nanosheets grown in situ on the CNT show a high reversible capacity of about 250 mA h g−1 and an ultra-high rate capability. The full-cells based on them are well cycled in a DME-based electrolyte and show a great promise for large-scale energy storage.

Solvothermal synthesized LiMn1−xFexPO4@C nanopowders with excellent high rate and low temperature performances for lithium-ion batteries

Mixed-carbon coated LiMn1−xFexPO4 (x = 0, 0.2, 0.5, 1) nano-particles are synthesized by a novel solvothermal approach. All of these powders possess a uniform particle size distribution around 150 nm and a carbon coating layer of about 2 nm. The LiMn1−xFexPO4@C samples with a carbon content of 2 wt% have an optimal electrochemical performance. The average voltage platform of LiMn1−xFexPO4@C increases with the increased Mn/Fe ratio, but declines gradually during electrochemical cycling. The LiMn0.5Fe0.5PO4 sample shows a high energy density (568 W h kg−1), good cycleability (97.1%, 100 cycles) and excellent rate capability (120.2 mA h g−1, 20C) at room temperature. Simultaneously, the LiMn0.5Fe0.5PO4 and LiFePO4 samples also show excellent low temperature electrochemical performance with specific capacities of 109.4 and 138.8 mA h g−1 with average discharge voltages of 3.476 V and 3.385 V, respectively, at −12 °C. Even at −20 °C, their discharge specific capacities are 71.7 and 82.3 mA h g−1 at 3C, respectively.

Porous carbon-coated NaTi2(PO4)3 with superior rate and low-temperature properties

Nanosized porous carbon-coated NaTi2(PO4)3 (NTP) particles with superior rate and low-temperature properties are synthesized by a hydrothermal process combined with different carbon coating steps. Their structures and electrochemical performances are analyzed by X-ray diffraction, scanning/transmission electron microscopies, Raman spectroscopy, N2 adsorption/desorption measurement and galvanostatic cell cycling. The optimized carbon-coated NTP sample NTP@C-2 shows superb rate performance with a charge capacity of 110.9 mA h g−1 at 30C rate, i.e. 97.0% retention of its capacity at 0.5C. After 1000 cycles at 10C, the reversible capacity can still reach 105.6 mA h g−1 with a very slow capacity decay of 0.0022% per cycle. Even at −20 °C, NTP@C-2 can still deliver a capacity of 97.6 mA h g−1 at 10C and 61.1 mA h g−1 at 20C. These excellent electrochemical performances can be attributed to both the nanosized porous architecture and the highly graphitic carbon coating. The use of a small amount of Na3V2(PO4)3 intermediate powder accounts for the formation of more sp2-type carbon coating. Such an NTP powder provides a promising anode material for high power sodium-ion batteries.

Synthesis of different CuO nanostructures by a new catalytic template method as anode materials for lithium-ion batteries

CuO powders composed of different rod-like clusters or dandelion-like nanospheres are prepared by a low-temperature thermal decomposition process of Cu(OH)2 precursors, which are obtained via a catalytic template method. A tentative mechanism is proposed to explain the formation and transformation of different Cu(OH)2 nanostructures. X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, field-emission scanning electron microscopy, transmission electron microscopy, infrared spectra analysis, Brunauer–Emmett–Teller measurements, and galvanostatic cell cycling are employed to characterize the structures and electrochemical performance of these CuO samples. The results show that these CuO samples obtained after 500 °C calcination have a stable cycling performance with a reversible capacity of over 587 mA h g−1 after 50 cycles. The dandelion-like CuO electrode shows the best rate performance with a high capacity of 511 mA h g−1 at 4C.

A comparative study on nanocrystalline layered and crystalline cubic TiP2O7 for rechargeable Li/Na/K alkali metal batteries

We report, for the first time, that a nanocrystalline layered TiP2O7 as a cathode material for Li-, Na- and K-alkali metal batteries is prepared by a solvothermal process followed by a heat treatment at 600 °C. For comparison, a crystalline cubic TiP2O7 is also synthesized at 800 °C. It is clarified that the layered TiP2O7 is slightly poorer for lithium storage but much better for sodium and potassium storages than the cubic phase. The detailed electrochemical processes are investigated by means of ex situ XRD analyses. Different from the two-phase co-existence mechanism for the cubic phase, a solid-solution mechanism is identified for the layered phase to follow in the Li/Na/K intercalation reactions based on electrochemical and structural studies. To overcome the poor electronic conductivity limit for high rate applications, carbon coating is employed on the TiP2O7 samples. The carbon-coated layered phase TiP2O7 (600 °C) displays fairly reversible capacity close to 100 mA h g−1 in both Li and Na rechargeable alkali metal batteries. It is a promising electrode material for large energy storage systems.

A novel lithium-ion battery comprising Li-rich@Cr 2 O 5 composite cathode and Li 4 Ti 5 O 12 anode with controllable coulombic efficiency

Through meticulous design, a Li-lacking Cr2O5 cathode is physically mixed with Li-rich Li1.2Ni0.13Co0.13Mn0.54O2 (LNCM) cathode to form composite cathodes LNCM@xCr2O5 (x = 0, 0.1, 0.2, 0.3, 0.35, 0.4, mass ratio) in order to make use of the excess lithium produced by the Li-rich component in the first charge-discharge process. The initial coulombic efficiency (ICE) of LNCM half-cell has been significantly increased from 75.5% (x = 0) to 108.9% (x = 0.35). A novel full-cell comprising LNCM@Cr2O5 composite cathode and Li4Ti5O12 anode has been developed. Such electrode accordance, i.e., LNCM@Cr2O5//Li4Ti5O12 (“L-cell”), shows a particularly high ICE of 97.7%. The “L-cell” can transmit an outstanding reversible capacity up to 250 mA h g−1 and has 94% capacity retention during 50 cycles. It also has superior rate capacities as high as 122 and 94 mA h g−1 at 1.25 and 2.5 A g−1 current densities, which are even better in comparison of Li-rich//graphite full-cell (“G-cell”). The high performance of “L-cell” benefiting from the well-designed coulombic efficiency accordance mechanism displays a great potential for fast charge-discharge applications in future high-energy lithium ion batteries.摘要本文将缺锂态的Cr2O5正极材料与Li1.2Ni0.13Co0.13Mn0.54O2(LNCM)富锂相正极材料进行物理混合, 形成了复合正极材料LNCM@xCr2O5(x = 0,0.1,0.2,0.3,0.35, 0.4), 从而在第一次充放电过程中达到有效利用富锂相所产生的不可逆的锂离子. 复合之后, LNCM半电池的首次库仑效率(ICE)得到显著提高, 从75.5(x = 0)提高到了108.9(x = 0.35). LNCM@Cr2O5复合正极材料和Li4Ti5O12负极材料匹配而成的新型锂离子全电池, 即LNCM@Cr2O5//Li4Ti5O12(L电池)表现出高达97.7的ICE. 不仅如此, L电池还表现出了高达250 mA h g—1的可逆容量, 并且 在循环50次之后仍具有94%的容量保持率. 此外, 在1.25和2.5 A g—1电流密度下, 它还具有高达122和94 mA h g—1的放电比容量, 远远优于LNCM//石墨全电池(G电池). L电池的高性能得益于精心设计的库仑效率匹配机制, 并且在未来高能量锂离子电池的快速充放电应用中表现出巨大的潜力.