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Ternary transition metal oxides (TMOs) are deemed as promising anode materials of Li-ion batteries (LIBs) owing to their large theoretical capacity and rich redox reaction. Nevertheless, the inherent semiconductor characteristic and enormous volume variation of TMOs during cycling bring about sluggish reaction kinetics, fast capacity fading, and poor rate capability. In this study, three-dimensional (3D) porous CoNiO2@CTP architectures, i.e., CoNiO2 microspheres combined with coal tar pitch-derived porous carbon, were designed and synthesized through a one-step hydrothermal method followed by a heat treatment process for the first time. The microsphere morphology increases the contact area between the anode and electrolyte, shortens the transport distance of Li+ ions, and reduces the agglomeration. The existence of the CTP layer provides rich charge transmission paths, improves the electronic conductivity of CoNiO2 and provides abundant active sites for Li+ storage. Owing to the synergistic effect of porous carbon and microsphere morphology of CoNiO2, the CoNiO2@CTP (10.0 wt%) anode shows remarkable electrochemical performance with a high charge capacity (1437.5 mA h g−1 at 500 mA g−1), good rate performance (839.76 mA h g−1 even at 1 A g−1), and remarkable cycle durability (741.4 mA h g−1 after 1000 cycles at 1 A g−1), which is significantly better than pristine CoNiO2. This study not only provides a simple strategy for high-value utilization of CTP but also offers cost-effective CoNiO2@CTP architectures for high-performance LIBs. [ABSTRACT FROM AUTHOR]

The Li2MoO3 (LMO) material is one promising cathode material for lithium-ion batteries due to its high specific capacity and absence of oxygen release. However, its surface instability in air and poor conductivity have limited its application. To solve these problems, the Ru element has been successfully introduced into the LMO lattice with the aid of the molten salt method. XRD and TEM characterization showed that the introduction of Ru does not change the crystal structure but expands the crystal plane spacing of the {001} facets, which is further evidenced by density functional theory (DFT) calculations. XPS and EDS tests indicated that the introduction of Ru inhibits the oxidation of Mo species and leads to a more uniform distribution of the material. In addition, DFT calculations revealed that covalent interactions are formed between Mo4d/Ru4d and O2p orbitals, leading to a significant reduction of the band gap. Therefore, Ru-doped samples exhibit good electrochemical performances. The initial discharge capacity of an LMRO-2 sample reaches 299.1 mA h g−1 at a 1C rate, and the capacity remains at 125.2 mA h g−1 after 100 cycles. In comparison, the initial discharge capacity of pure phase sample LMO is only 250.5 mA h g−1 under the same conditions, and the capacity remains only at 76.5 mA h g−1 after 100 cycles. The present results confirmed that Ru doping is an effective strategy to improve the performance of the LMO cathode material. [ABSTRACT FROM AUTHOR]

ZnTiO3 and ZnTiO3–CeO2 microspheres with particle sizes of about 100–300 nm were synthesized for the first time by a simple solvothermal process followed by calcination. The results indicate that CeO2 modification does not alter the morphology of the microspheres. ZnTiO3–CeO2 (0, 3, 6, and 9 wt%) show an initial charge (discharge) capacity of 171.01 (253.2), 204.6 (507.5), 213.4 (451.6) and 126.2 (367.2) mA h g−1 at 500 mA g−1, respectively. After 500 cycles, the corresponding charge (discharge) capacities were 191.1 (192.3), 298.7 (300.3), 322.4 (328.5) and 211.2 (212.3) mA h g−1, respectively. Obviously, the charge (discharge) capacities of the ZnTiO3–CeO2 composites are superior to those of pristine ZTO, which demonstrates that the Li storage performance of the CeO2-modified ZTO electrodes is improved. The CeO2 shell provides a good electronic contact between ZnTiO3 and CeO2, decreasing charge transfer resistance and facilitating the charge transportation of the ZnTiO3–CeO2 composite. In addition, the formed phase interface between CeO2 and ZnTiO3 may provide more active sites for electrochemical reactions, improving the reversibility of Li-ion intercalation and decreasing the electrochemical polarization during cycling, especially at high current densities. Therefore, such ZnTiO3–CeO2 microspheres can be regarded as hopeful candidates for anode materials for Li-ion batteries. [ABSTRACT FROM AUTHOR]

Platanus fruit-like CuCo2S4 microspheres were fabricated by using a facile hydrothermal method followed by a sulfidation process. As a lithium storage material, they deliver an outstanding initial specific capacity of 1119.3 mA h g−1 at 0.05 A g−1 and a high reversibility of 954 mA h g−1 over 200 cycles even at 1 A g−1. In addition, when applied in supercapacitors they display a superb specific capacitance of 824 F g−1 at 1 A g−1, even over 10 000 cycles and they can also maintain 75% retention at 5 A g−1 and exhibit good reversibility. Furthermore, an advanced asymmetric supercapacitor (ASC) exhibits an advantageous energy density of 36.67 W h kg−1 when the power density increases up to 750 W kg−1. Additionally, the assembled device can easily light a 1.5 V bulb for several minutes. The excellent performance of CuCo2S4 is due to the bimetallic synergistic effect and the unique platanus fruit-like microsphere architecture, which can limit the restacking of the structure and provide suitable voids. This excellent performance confirms that platanus fruit-like CuCo2S4 microspheres are a promising electrode material for energy storge. This work will provide a new strategy to prepare high-performance bimetallic sulfide anode materials by a facile method. [ABSTRACT FROM AUTHOR]

Na2Li2Ti6O14 particles were prepared by a simple solid-state process, and then g-C3N4-coated Na2Li2Ti6O14 composites were constructed by a facile solution route for the first time. The g-C3N4-coated Na2Li2Ti6O14 multicomponent composites because of their unique architecture as negative materials for Li-ion batteries can be expected to exhibit a significantly improved cycling stability and reversible capacity even at high rates. g-C3N4 (5 wt%)-coated Na2Li2Ti6O14 shows a discharge (charge) capacity of 184.4 (184.3) mA h g−1 at 500 mA g−1 after 100 cycles, which is larger than that of pristine Na2Li2Ti6O14 with a discharge (charge) capacity of 122.8 (122.0) mA h g−1. The use of g-C3N4 with a carbon framework containing abundant nitrogen provides more active sites and surface defects for redox reactions and Li-ion transport. The g-C3N4 coating decreases the impedance between the electrolyte and Na2Li2Ti6O14 and enhances the charge transfer, ionic conductivity and diffusion ability of Li ions of Na2Li2Ti6O14. This work offers an efficient way to design high-performance Na2Li2Ti6O14-based materials for advanced lithium ion battery, and g-C3N4 (5 wt%)-coated Na2Li2Ti6O14 shows an enormous potential as a negative material for next generation Li-ion batteries with excellent performance. [ABSTRACT FROM AUTHOR]

First principles computation methods play an important role in developing and optimizing new energy storage and conversion materials. The thermodynamic stability, transport properties of the carriers and the lithium diffusion mechanisms of LiFeSO4F compounds are calculated by using the first principles computation. According to the calculated formation enthalpies and electronic properties, it can be concluded that both LiFeSO4F and delithiated FeSO4F have high thermodynamic stability during cycling. Band structure analysis reveals that the conduction and valence bands that are mainly composed of Fe3d states are rather localized, leading to large band gaps and effective masses of the carriers. LiFeSO4F and FeSO4F thus exhibit poor electronic conductivities. To improve the electronic conductance of the materials, introduction of delocalized states in the band gap region via doping or nano-crystallization of the electrode material is still necessary. Further investigations on lithium diffusion dynamics suggest that suitable amounts of lithium vacancies at the 2i sites are particularly crucial. Under high lithium concentration conditions, these vacancies are very helpful to initiate the transfer of lithium into the empty positions by eliminating the Li–Li repulsions and then activate the diffusion of lithium through the channels. While under low lithium concentration conditions, they can act as intermediate sites effectively for several high-speed diffusion channels. As the calculated activation energies for the possible diffusion paths (0.185–0.563 eV) are very small, LiFeSO4F and FeSO4F thus show excellent ionic conductance. [ABSTRACT FROM AUTHOR]

Novel submicron Li5Cr7Ti6O25, which exhibits excellent rate capability, high cycling stability and fast charge–discharge performance is constructed using a facile sol–gel method. The insights obtained from this study will benefit the design of new negative electrode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries are considered as one of the most promising power sources for energy storage system for a wide variety of applications such as electric vehicles (EVs) or hybrid electric vehicles (HEVs). The anode material often plays an important role in the determination of the safety and cycling life of lithium-ion batteries. Among all anode materials, spinel Li4Ti5O12 has been considered as one the most promising anode candidates for the next-generation large-scale power lithium-ion batteries used for HEVs or EVs because it has a high potential of around 1.55 V (vs. Li/Li+) during charge and discharge, excellent cycle life due to the negligible volume change, and high thermal stability and safety. In this review, we present an overview of the breakthroughs in the past decade in the synthesis and modification of both the chemistry and morphology of Li4Ti5O12. An insight into the future research and further development of Li4Ti5O12 composites is also discussed. [ABSTRACT FROM AUTHOR]

Ternary transition metal oxides (TMOs) are deemed as promising anode materials of Li-ion batteries (LIBs) owing to their large theoretical capacity and rich redox reaction. Nevertheless, the inherent semiconductor characteristic and enormous volume variation of TMOs during cycling bring about sluggish reaction kinetics, fast capacity fading, and poor rate capability. In this study, three-dimensional (3D) porous CoNiO 2 @CTP architectures, i.e. , CoNiO 2 microspheres combined with coal tar pitch-derived porous carbon, were designed and synthesized through a one-step hydrothermal method followed by a heat treatment process for the first time. The microsphere morphology increases the contact area between the anode and electrolyte, shortens the transport distance of Li + ions, and reduces the agglomeration. The existence of the CTP layer provides rich charge transmission paths, improves the electronic conductivity of CoNiO 2 and provides abundant active sites for Li + storage. Owing to the synergistic effect of porous carbon and microsphere morphology of CoNiO 2 , the CoNiO 2 @CTP (10.0 wt%) anode shows remarkable electrochemical performance with a high charge capacity (1437.5 mA h g -1 at 500 mA g -1 ), good rate performance (839.76 mA h g -1 even at 1 A g -1 ), and remarkable cycle durability (741.4 mA h g -1 after 1000 cycles at 1 A g -1 ), which is significantly better than pristine CoNiO 2 . This study not only provides a simple strategy for high-value utilization of CTP but also offers cost-effective CoNiO 2 @CTP architectures for high-performance LIBs.

The Li 2 MoO 3 (LMO) material is one promising cathode material for lithium-ion batteries due to its high specific capacity and absence of oxygen release. However, its surface instability in air and poor conductivity have limited its application. To solve these problems, the Ru element has been successfully introduced into the LMO lattice with the aid of the molten salt method. XRD and TEM characterization showed that the introduction of Ru does not change the crystal structure but expands the crystal plane spacing of the {001} facets, which is further evidenced by density functional theory (DFT) calculations. XPS and EDS tests indicated that the introduction of Ru inhibits the oxidation of Mo species and leads to a more uniform distribution of the material. In addition, DFT calculations revealed that covalent interactions are formed between Mo 4d /Ru 4d and O 2p orbitals, leading to a significant reduction of the band gap. Therefore, Ru-doped samples exhibit good electrochemical performances. The initial discharge capacity of an LMRO-2 sample reaches 299.1 mA h g -1 at a 1C rate, and the capacity remains at 125.2 mA h g -1 after 100 cycles. In comparison, the initial discharge capacity of pure phase sample LMO is only 250.5 mA h g -1 under the same conditions, and the capacity remains only at 76.5 mA h g -1 after 100 cycles. The present results confirmed that Ru doping is an effective strategy to improve the performance of the LMO cathode material.

ZnTiO 3 and ZnTiO 3 -CeO 2 microspheres with particle sizes of about 100-300 nm were synthesized for the first time by a simple solvothermal process followed by calcination. The results indicate that CeO 2 modification does not alter the morphology of the microspheres. ZnTiO 3 -CeO 2 (0, 3, 6, and 9 wt%) show an initial charge (discharge) capacity of 171.01 (253.2), 204.6 (507.5), 213.4 (451.6) and 126.2 (367.2) mA h g -1 at 500 mA g -1 , respectively. After 500 cycles, the corresponding charge (discharge) capacities were 191.1 (192.3), 298.7 (300.3), 322.4 (328.5) and 211.2 (212.3) mA h g -1 , respectively. Obviously, the charge (discharge) capacities of the ZnTiO 3 -CeO 2 composites are superior to those of pristine ZTO, which demonstrates that the Li storage performance of the CeO 2 -modified ZTO electrodes is improved. The CeO 2 shell provides a good electronic contact between ZnTiO 3 and CeO 2 , decreasing charge transfer resistance and facilitating the charge transportation of the ZnTiO 3 -CeO 2 composite. In addition, the formed phase interface between CeO 2 and ZnTiO 3 may provide more active sites for electrochemical reactions, improving the reversibility of Li-ion intercalation and decreasing the electrochemical polarization during cycling, especially at high current densities. Therefore, such ZnTiO 3 -CeO 2 microspheres can be regarded as hopeful candidates for anode materials for Li-ion batteries.

Platanus fruit-like CuCo 2 S 4 microspheres were fabricated by using a facile hydrothermal method followed by a sulfidation process. As a lithium storage material, they deliver an outstanding initial specific capacity of 1119.3 mA h g -1 at 0.05 A g -1 and a high reversibility of 954 mA h g -1 over 200 cycles even at 1 A g -1 . In addition, when applied in supercapacitors they display a superb specific capacitance of 824 F g -1 at 1 A g -1 , even over 10 000 cycles and they can also maintain 75% retention at 5 A g -1 and exhibit good reversibility. Furthermore, an advanced asymmetric supercapacitor (ASC) exhibits an advantageous energy density of 36.67 W h kg -1 when the power density increases up to 750 W kg -1 . Additionally, the assembled device can easily light a 1.5 V bulb for several minutes. The excellent performance of CuCo 2 S 4 is due to the bimetallic synergistic effect and the unique platanus fruit-like microsphere architecture, which can limit the restacking of the structure and provide suitable voids. This excellent performance confirms that platanus fruit-like CuCo 2 S 4 microspheres are a promising electrode material for energy storge. This work will provide a new strategy to prepare high-performance bimetallic sulfide anode materials by a facile method.

Na2Li2Ti6O14 particles were prepared by a simple solid-state process, and then g-C3N4-coated Na2Li2Ti6O14 composites were constructed by a facile solution route for the first time. The g-C3N4-coated Na2Li2Ti6O14 multicomponent composites because of their unique architecture as negative materials for Li-ion batteries can be expected to exhibit a significantly improved cycling stability and reversible capacity even at high rates. g-C3N4 (5 wt%)-coated Na2Li2Ti6O14 shows a discharge (charge) capacity of 184.4 (184.3) mA h g-1 at 500 mA g-1 after 100 cycles, which is larger than that of pristine Na2Li2Ti6O14 with a discharge (charge) capacity of 122.8 (122.0) mA h g-1. The use of g-C3N4 with a carbon framework containing abundant nitrogen provides more active sites and surface defects for redox reactions and Li-ion transport. The g-C3N4 coating decreases the impedance between the electrolyte and Na2Li2Ti6O14 and enhances the charge transfer, ionic conductivity and diffusion ability of Li ions of Na2Li2Ti6O14. This work offers an efficient way to design high-performance Na2Li2Ti6O14-based materials for advanced lithium ion battery, and g-C3N4 (5 wt%)-coated Na2Li2Ti6O14 shows an enormous potential as a negative material for next generation Li-ion batteries with excellent performance.

To improve their electrochemical performance and structural stability, Na 2 Li 2 Ti 6 O 14 (NLTO) nanoparticles were synthesized and then coated with a very thin MgF 2 layer. Microscopy confirmed that the MgF 2 -NLTO particles are about 150-250 nm in size, and that the thickness of the MgF 2 layer for the MgF 2 -NLTO-5 sample is ∼5 nm. Electrochemical measurements showed that the charge-discharge specific capacities of the five samples under a current density of 50 mA g -1 after 100 cycles are 110.4/110.7, 150.7/151.3, 181.1/182.1, 205.7/206.9 and 238.9/239.2 mA h g -1 , showing that the performance of MgF 2 -NLTO-5 is the best among all the samples. Thanks to the thin coating layer, the polarization of the anode was reduced significantly, and its reversibility and lithium diffusion dynamics were also improved obviously. The performance improvement can be attributed to the suppression of surface corrosion and the enhancement of structural stability., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Novel submicron Li5Cr7Ti6O25, which exhibits excellent rate capability, high cycling stability and fast charge-discharge performance is constructed using a facile sol-gel method. The insights obtained from this study will benefit the design of new negative electrode materials for lithium-ion batteries.