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Lithium vanadium fluorophosphate (LiVPO4F) composite with three-dimensional conductive networks architecture is synthesized with synergistic modification of pyrolytic carbon (C), multi-walled carbon nanotubes (MWCNTs) and graphene sheets (rGO). The differences between LiVPO4F@C, LiVPO4F@C/MWCNTs, LiVPO4F@C/rGO and LiVPO4F@C/MWCNTs/rGO composites are compared through a variety of characterization means. By means of SEM and TEM analysis, it can be seen that pyrolyzed C, MWCNTs and rGO are interwoven, which forms a three-dimensional conductive network structure wrapping the LiVPO4F particles. The difference of discharge specific capacity between LiVPO4F@C and LiVPO4F@C/MWCNTs/rGO composites is becoming larger and larger with the increase of charge-discharge rate. Additionally, CV and EIS results indicate that the LiVPO4F@C/MWCNTs/rGO has the smallest polarization value and charge transfer impedance (Rct) as well as the highest diffusion coefficient of lithium ion (DLi+) in all samples. Consequently, LiVPO4F@C/MWCNTs/rGO composite exhibits a high rate capability (97.9 mAh/g cycles at 10 C) and cycling stability (93.74% capacity retention over 800 cycles at 10 C)，showing potential application for high power LIB with high voltage.

The electrochemical properties of LiNi0.6Co0.2Mn0.2O2, such as cycling stability, rate capacity and coulomb efficiency, are not fairly well at large rate, high cutoff voltage and elevated temperature. In this article, a uniform nanoscale graphene@TiO2 coating layer is skillfully formed on the surface of LiNi0.6Co0.2Mn0.2O2 via an artful sol-gel-based method. The rGO@TiO2 layer is evidenced by a series of detections, and the structures of the pristine and coated materials are investigated in detail. It indicates that the graphene@TiO2 layer with a thickness of ∼2 nm is uniformly covered on the LiNi0.6Co0.2Mn0.2O2 particles. The “synergistic effects” of graphene@TiO2 composite plays an important role in improving the comprehensive electrochemical performances of the cathode material. Compared with the pristine material, the graphene@TiO2 co-modified LiNi0.6Co0.2Mn0.2O2 shows enhanced electrochemical performances at large rate, elevated temperature, and high cutoff voltage. Particularly, it displays capacity retentions of 93.7% and 89.2% after 150 cycles at 1 C and 2 C, respectively, over 3.0–4.5 V. Even at high temperature of 55 °C and upper operating voltage of 4.5 V, the capacity retention of graphene@TiO2-coated sample increases almost 50% compared with the pristine sample after 150 cycles.

The layered transition metal oxide of sodium-ion batteries (SIBs) has a high specific capacity and has been widely studied by scientific researchers. The O3 phase NaCrO2 (NCO) which is a kind of potential SIBs cathode material has good thermal stability and desirable safety performance. However, it suffers from complex phase transitions and rapid capacity decay during cycles. Herein, the robust dual-phase modification layer is construct on the surface of NCO to enhance its surface and interface stability. A dispersed pyrolytic carbon layer and the island LaF3 on the surface of the materials are formed by heat treatment of NCO with PVDF and La2(CO3)3•8H2O. The effects of the modification amount on NCO structure, electrochemical performance and the capacity fading mechanisms are characterized by various methods. The results show that the surface fluorination modification not only helps to improve the conductivity of the surface of the materials by conductive carbon network and reduce the side reactions, but also enhances structural and interface stability by the stable LaF3 decoration and lattice oxygen replacement with pyrolysis of PVDF. It is worth noting that this modification method improves the thermodynamic stability of the electrode interface by introducing a highly stable coating on the electrode and it's beneficial to improve the rate performance and cycle performance of the material. As a result, the modified NCO displays good rate capability and cycle performance with 80.86% after 900 cycles at 2C rate, and the specific capacity is 76.7 mAh g-1 at 40C rate. This investigation highlights the advantages of this surface modification treatment method with respect to the surface stability of NCO and suppressing phase transition.

WO3-coated Li1.2Ni0.2Mn0.6O2 cathode materials have been synthesized by using co-precipitation method along with a liquid-evaporation coating process. Investigations via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) reveal that a WO3 layer is uniformly distributed on the surface of bulk Li1.2Ni0.2Mn0.6O2. After coating appropriate amount of WO3, the Li-rich cathode materials exhibit improved electrochemical performance. In particular, the 2 wt% WO3 coated sample (WO3-0.02 LLNMO) can deliver an initial discharge capacity of 252.2 mA h g-1 with a low irreversible capacity loss of 44.6 mA h g-1 and remarkable cycling stability of 97% capacity retention after 100 cycles at a current density of 52 mA g−1. This is mainly due to the effects of the WO3 coating layer which can suppress the initial activation of Li2MnO3 and improve the stability of surface structure of Li-rich materials by protecting it from corrosion by HF and other side reactions.

Ni-rich ternary cathode materials have attracted great attention because of its high energy density, good cycle performance and high rate performance. However, it suffers from the poor electrochemical performance at elevated temperature and high cut-off voltage due to intrinsic grievous side effects. Herein, a core-shell structure of LiNi0.6Co0.2Mn0.2O2 as the core and Li1.2Ni0.2Mn0.6O2 as the shell which integrated the structural stability of Ni-rich materials and the surface chemical stability of Li-rich materials was purposefully designed via a polyvinyl pyrrolidone (PVP)-assisted sol-gel method and a novel chemical activation for the Li-rich shell with AlF3 treatment. Research by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy methods (TEM), and energy dispersive X-ray spectrometer (EDS) have been proved that the surface of the host materials was deposited with a uniform shell layer of Li1.2Ni0.2Mn0.6O2 and AlF3 particles. As a result, the core-shell materials displayed excellent cycle performance: 94.0% capacity retention after 100 cycles (2.0–4.5 V under 1C and 25 °C) especially at high temperature≈50 °C: 86.5% capacity retention.

Ni-rich cathode material is considered to be a promising cathode for commercial applications in lithium-ion batteries because of its low cost and high capacity. However, its chemical, electrochemical, and mechanical instability at the cathode-electrolyte interface cause a series of problems, such as inferior electrochemical performance and serious safety concerns. To construct a stable interface, we develop a simple and reproducible method to encapsulate LiNi0.8Co0.1Mn0.1O2 within ionic and electronic conductive half-cyclized polyacrylonitrile. The images of scanning electron microscopy and transmission electron microscopy prove that a continuous polymer layer formed on the surface of the cathode material. The organic coating layer is composed of both cyano groups that provide lithium-ion transport channels and cycled cyano groups that conduct electrons. At the same time, the elasticity of the coating polymer layer can maintain the mechanical stability of the cathode material during charge/discharge. Electrochemical studies demonstrate that the cycle and rate performances of LiNi0.8Co0.1Mn0.1O2 are obviously improved. After 100 cycles at a current density of 200 mA•g−1, the capacity retention is increased from 83.93 to 96.24%. The design of this real conformal coating strategy provides a possible solution for the modification of other cathode materials.

A green strategy is designed for synthesizing LiMn0.8Fe0.2PO4/C composites bases on mechano-chemical liquid-phase activation technique. The micro-nano spherical precursor is prepared by the effective redox reaction between MnO2 and H2O2 in H3PO4 aqueous solution with subsequent addition FeC2O4•2H2O and Li2CO3, which is followed by spray drying. The dense LiMn0.8Fe0.2PO4/C microspheres are formed from conformal carbon coating connected with primary nano-sized particles, which provides rapid electron and ion transport pathways during the electrode reaction. The obtained LiMn0.8Fe0.2PO4/C cathode exhibits reduced electrochemical polarization with high voltage platform and high discharge capacity of 159 mAh g −1 at 0.1 C. Even at high rate of 10 C, the composite shows an impressing discharge capacity of 130 mAh g −1 with obviously stable plateau. Besides, uniformly conductive carbon network distributed all over the primary nano-sized particles effectively inhibits the occurrence of interfacial side reactions during electrode cycling, and the electrode exhibits good cycling stability with capacity retention rate of 95% after 500 cycles at 1 C. This work provides a scalable route to fabricate high energy density LiMn0.8Fe0.2PO4/C cathode with excellent rate performance for Li-ion battery.

A facile in-situ hydrolytic coating strategy has been suggested to architecture LiAlSiO4 (LASO)-coated LiNi0.8Co0.1Mn0.1O2 (LNCM) cathode material for lithium-ion batteries. Homogeneous LASO coating layer, as an one-dimensional lithium ion conductor, on the surface of LNCM is observed clearly and ascertained jointly by several testing methods. The effects of LASO coating layer on physicochemical properties, electrochemical properties and electrochemical kinetics of LNCM cathode material have been rigorously investigated by various tests. The cycling stability, rate capability and Li+ ion diffusion rate are enhanced evidently after LASO coating. Moreover, the polarization, impedance increase and particles cracking after cycles under the high cut-off voltage are greatly improved. These effective and obvious improvements are ascribed to the LASO coating layer, which could effectively inhibit the occurrence of side reactions and HF erosion and provide a fast ion diffusion channel for lithium ions on the surface of LNCM.

Ni-based layered LiNi0.5Co0.2Mn0.3O2 (NCM) compounds coated with lithium titanium oxide for lithium ion batteries were successfully achieved through a simple solid state synthesis process using TiO2 powder and CH3COOLi. Systematical measurements in structure, morphology and electrochemical properties have been applied. X-ray diffraction patterns showed the existence and conversion of lithium titanium oxide (Li4Ti5O12 and Li7Ti5O12 are labeled as LTO). A coating layer in the form of LTO could be observed and the thickness was approximately 10 nm with uniform distribution. Similarly, XPS was performed to confirm the existence of LTO. 1.0 wt.% LTO-coated NCM material exhibited higher capacity retentions of 91.0% than that of the bare one (64.3%) after 100 cycles at cutoff voltages of 4.5 V. Meanwhile, the LTO-coated NCM material showed significantly improved thermal stability compared with the pristine sample at an elevated 60 °C. In addition, it has proved that it is effective to enhance the electrochemical performances of electrodes by LTO modification.

Abtract LiNi0.80Co0.15Al0.05O2 has been widely pursued as an alternative to LiCoO2 cathode materials for lithium ion batteries because of its high capacity and acceptable cycling property. However, that NCA can react with commercialized electrolyte during cycling restrains its wide use. Here, olivine structured LiMnPO4 has been introduced to modify the surface of NCA by a sol-gel method. Characterizations from structure, morphology and composition analysis technologies demonstrate that a LiMnPO4 layer has been uniformly coated on NCA particles. The electrochemical performance and thermo stability of modified samples are characterized by electrochemical tests, XRD and metallic nail penetration tests. The olivine structured skin, which provides structural and thermal stability, is used to encapsulate the high powered core via using the effective coating technique. The modified material displays a high discharge capacity of 211.0 mAh g−1 at 0.2 C and better rate performance and promoted cycling stability than the uncoated control sample. Furthermore, the thermal stability of coated sample in the delithiated state is upgraded to the pristine powders remarkably.

LiNi0.5Mn0.5O2 suffers from surface structure instability and capacity degradation upon cycling, and single doping or coating cannot effectively solve the problem. In this work, the Sb-modified LiNi0.5Mn0.5O2 is successfully prepared by solid-state reaction process at high temperature, which simultaneously realizes Sb doping and Sb2O3 coating. Electrochemical experiments show that the Sb-modified LiNi0.5Mn0.5O2 material has enhanced electrochemical performance. The capacity retention of the Sb-modified LiNi0.5Mn0.5O2 material is 81.00% at 1.0 C after 250 cycles, while it is 59.08% for the bare sample, and performs 105.7 mAh g−1 at 5 C compared to 76.6 mAh g−1 for the bare sample. Therefore, Sb doping and Sb2O3 coating collaboration are beneficial to enhance electrochemical performance. This effective design strategy can be used to improve the electrochemical performance of other layered cathode materials.

A surface cladding of nano-sized Li 2 SnO 3 powder on Ni-rich layered LiNi 0.5 Co 0.2 Mn 0.3 O 2 compounds for lithium ion batteries have been successfully achieved through a two-step synthesis process. The structures and morphologies of as-prepared samples have been analyzed. A cladding layer of Li 2 SnO 3 can be distinguished on the surface of host material and the thickness is about 15 nm with uniform distribution. The optimized Li 2 SnO 3 -coated sample displays better rate performance and higher capacity retentions of 94.9% at 10 C after 100 cycles than that of the bare one (68.3%) at 3.0–4.5 V. In addition, Li 2 SnO 3 as an effective coating layer can enhance the cycle stability and rate property of electrodes.

MnFe 2 O 4 /reduced graphene oxide nanocomposite (MnFe 2 O 4 /rGO) has been synthesized via a green reduction-coprecipitation method for the first time, which involved in situ reduction of GO in presence of Fe 2+ and the ensuing coprecipitation of Fe 3+ and Mn 2+ onto the surface of rGO. The resultant MnFe 2 O 4 /rGO was then employed as the precursor to fabricate LiMn 1/3 Fe 2/3 PO 4 /reduced graphene oxide/carbon composite (LiMn 1/3 Fe 2/3 PO 4 /rGO/C) cathode material for Li-ion batteries. The composite consists of homogeneous Mn-Fe distributed LiMn 1/3 Fe 2/3 PO 4 with its primary particles (∼200 nm) covered and connected by both pyrolytic carbon and rGO sheets, which could prevent the aggregation of the particles as well as construct an interconnected conductive network for rapid transmission of electrons during charging and discharging process. The fabricated LiMn 1/3 Fe 2/3 PO 4 /rGO/C can deliver a discharge capacity of 94.8 mAh g −1 even at the high rate of 20C, and shows a capacity decay rate of only 6.25% after 900 long-term charge-discharge cycles. Moreover, the proposed synthesis strategy can also be applied to prepare other graphene-decorated multi-component cathode/anode materials for the Li-ion batteries.

In order to investigate the influences of Mg–Al–B co-substitution on LiNi 0.5 Co 0.2 Mn 0.3 O 2 material, the uniform and spherical doped Li[Ni 0.5 Co 0.2 Mn 0.3 ] 0.992 Mg 0.003 Al 0.003 B 0.002 O 2 material is successfully prepared through a simple solid state synthesis. X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) mapping, X-ray photoelectron spectroscopy (XPS) and electrochemical tests have been applied for material characterizations and electrochemical measurements. Through the result of XRD and the Rietveld refinements, Mg, Al and B atoms may be incorporated into the crystal lattice. Similarly, the results of EDX and XPS confirm the existence of Mg 2+ , Al 3+ and B 3+ in accordance with the chemical formula. The Mg–Al–B co-substitution LiNi 0.5 Co 0.2 Mn 0.3 O 2 material shows excellent electrochemical performance, especially the superior cycling stability under high cutoff voltages. The Mg–Al–B co-substitution LiNi 0.5 Co 0.2 Mn 0.3 O 2 material exhibits the higher capacity retentions of 83.8%, 84.9%, 83.2% and 80.4% than that of the bare one (71%, 62.5%, 40.9% and 25%) after 200 cycles at a cutoff voltage of 4.2, 4.3, 4.4 and 4.5 V, respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) confirm that the modification of Mg–Al–B co-substitution plays an important role in improving the electrochemical performance of the bare LiNi 0.5 Co 0.2 Mn 0.3 O 2 .

Due to its flexible two-dimensional layered structure and good hydrophilicity, graphene oxide (GO) is widely used to prepare composite electrode materials for lithium-ion batteries by co-precipitation in aqueous solutions. However, the purification process of GO prepared by the Hummers method is cumbersome and consumes a large amount of water. It also produces wastewater containing heavy metal manganese ions. What's more, both GO and manganese compounds are used during the synthesis of LiMn0.8Fe0.2PO4/reduced graphene oxide/carbon (LiMn0.8Fe0.2PO4/rGO/C) composite. In view of the issues above, a highly atom-economical route based on Hummers method is proposed in this paper to synthesize LiMn0.8Fe0.2PO4/rGO/C. The GO solution obtained by Hummers method is directly used as a substrate solution to prepare (Mn0.8Fe0.2)3(PO4)2·xH2O/GO precipitate, which is then used as a precursor to prepare LiMn0.8Fe0.2PO4/rGO/C by high temperature solid phase sintering. The obtained particles are evenly distributed and wrapped by a graphene-based three-dimensional conductive network. The synthesized composite exhibits good rate performance and cycling stability. In a word, this research develops a new route with high atomic economy and environmental friendliness for the large-scale production of LiMnxFe1-xPO4/rGO/C composites.

As a promising cathode material, LiNi0·8Co0·1Mn0·1O2 has merits of relatively low cost and high discharge specific capacity, but its shortcoming of poor cycle stability restricts its extensive application. To improve the electrochemical performance of LiNi0·8Co0·1Mn0·1O2, Al(H2PO4)3 is used for surface treatment. Al(H2PO4)3 can react with residual lithium on the surface of LiNi0·8Co0·1Mn0·1O2 to build bi-phase Li3PO4 and AlPO4 coating layer (abbreviated as “LNCM@ALP”). This co-coating layer with good Li+ conductivity and chemical stability against the electrolyte, which significantly improved the cycling stability and rate performance of the material. Based on a series of characterization methods, it is proved that bi-phase Li3PO4 and AlPO4 coating layer co-exist on the surface of LiNi0·8Co0·1Mn0·1O2, and stabilize the structure of surface-modified sample LiNi0·8Co0·1Mn0·1O2. The electrochemical test has shown the cycle and rate performance of the LNCM@ALP sample has been significantly improved. After 100 cycles, the capacity of 0.5 wt% co-coated LNCM@ALP decreases from 182.8 mAh g−1 to 167.8 mAh g−1with the retention rate of 91.79% compared with bare LiNi0·8Co0·1Mn0·1O2 of only 82.66%. And at the discharge capacity of 0.5 wt% coated-samples are 162.5 mAh g−1 and 150.2 mAh g−1 at 5C, 10C, which shows an excellently rate performance.

Improving the cycling stability of LiNi0.6Co0.2Mn0.2O2 at high voltage and high temperature has always been one of the critical directions for researchers to seek a breakthrough. In this study, a surface modification for LiNi0.6Co0.2Mn0.2O2 materials by coating with the conductive cyclized polyacrylonitrile (cPAN) is employed. The cyclized polyacrylonitrile formed by heat treatment of polyacrylonitrile is confirmed to have delocalized π bonds and therefore has good electronic conductivity. The polyacrylonitrile not involved in the reaction is expected to leave the coating with a certain ionic conductivity. The conductive coating layer enhances the rate of electron exchange and ion exchange of the electrodes. Besides, the cyclized polyacrylonitrile with elasticity not only suppresses the volume expansion of the host materials but also plays a central role in suppressing electrochemical polarization by providing a barrier to suppress the interfacial reactions and electrolyte decomposition. The results show that the rate performance and cycling stability of LiNi0.6Co0.6Mn0.6O2 at high voltage and high temperature are greatly improved by the surface modification.

Ni-rich LiNi0.8Co0.1Mn0.1O2 cathode material possesses advantages of high capacity and low cost, but the rapid capacity decline and power degradation during cycle process at high cut-off voltage limits its large-scale industrialization. Meanwhile, LiVPO4F modified with carbon based hybrid is relatively stable and has excellent electrochemical properties at higher cut-off voltage of 4.4–4.5 V. Based on the idea of secondary modification for cathode material, the LiVPO4F hybrid is used to modify LiNi0.8Co0.1Mn0.1O2 to obtain LiVPO4F-LiNi0.8Co0.1Mn0.1O2 composites. The presence of the LiVPO4F hybrid maintains interfacial stability, suppresses irreversible side reactions and sustains a relatively rapid charge transfer under high voltage. The LiVPO4F modified LiNi0.8Co0.1Mn0.1O2 composites delivers a discharge specific capacity of 140.0 mAh g−1 at high rate of 20 C, and achieves a cycle retention rate of 83.38% at 4.5 V after 150 cycles, revealing that good rate capability and cycling performance of LiNi0.8Co0.1Mn0.1O2 is improved-achieved by surface modification of LiVPO4F even at high cut-off voltage of 4.5 V.

In order to overcome the capacity fading of LiCoO 2 cathode material cycled in the voltage of 3.0–4.5 V (vs. Li/Li+), electrochemically active Li[Li 0.2 Mn 0.6 Ni 0.2 ]O 2 was coated onto the surface of LiCoO 2 by sol-gel method. The detrimental surface effects arising from the high Co-content are countered by the Li[Li 0.2 Mn 0.6 Ni 0.2 ]O 2 coating. The surface morphology and structure of bare and coated LiCoO 2 is characterized by scanning electron microscope (SEM) and X-ray diffraction spectroscopy (XRD). It is found that LiCoO 2 exhibits better high-voltage performance after coating with Li[Li 0.2 Mn 0.6 Ni 0.2 ]O 2 than before. Besides, the coating layer can significantly suppress the dissolution of Co in the electrolyte. Comparative data for the coated and uncoated materials are presented and discussed.

A series of Ni 0.6 Co x Mn 0.4-x (OH) 2 hydroxide precursors with x = 0.05, 0.1, 0.15, 0.2, 0.25 and 0.3 are prepared by co–precipitation method from sulfate solutions using NaOH and NH 4 OH as precipitation and complexing agents. Then, well–ordered layered LiNi 0.6 Co x Mn 0.4-x O 2 are synthesized by sintering the mixture of as–prepared precursors and LiOH · H 2 O at 820 °C for 12 h in flowing oxygen. Their structural and electrochemical properties are investigated using X–ray diffraction(XRD), scanning electron microscope(SEM), X–ray photoelectron spectroscopy(XPS), charge–discharge test, Cyclic voltammetry(C–V) and electrochemical impedance spectroscopy (EIS). The increase of the Co content in LiNi 0.6 Co x Mn 0.4−x O 2 leads to the decrease of the tap–density of the powders, the increase of discharge capacity and the deterioration of cycling performance. It also leads to the enhancement of the ratio Ni 3+ /Ni 2+ in LiNi 0.6 Co x Mn 0.4−x O 2 , confirmed by the XPS analysis. The results show that the sample with x = 0.2 has the highest tap–density, delivers an initial discharge capacity of 172.3 mAh g −1 at 1 C rate between 2.8 and 4.3 V, more than 94.1% of that is retained after 100 cycles, and also with excellent rate capability and high-temperature performance.

LiNi0.6Co0.2Mn0.2O2 cathode materials were synthesized from spherical and homogeneous mixed metal hydroxide Ni0.6Co0.2Mn0.2(OH)2 which was prepared by co–precipitation method. The synthetic conditions of the metal hydroxide, such as pH, amount of chelating, stirring speed, temperature, etc. were studied in detail. The homogeneous and spherical Ni0.6Co0.2Mn0.2(OH)2 precursor obtained in the optimized synthetic conditions had a high tap–density of 1.94 g cm−3. A well–ordered layer–structured and spherical LiNi0.6Co0.2Mn0.2O2 cathode material, with the tap–density of 2.59 g cm−3, was fabricated by calcinating the as-prepared Ni0.6Co0.2Mn0.2(OH)2 precursor and 5% excess LiOH·H2O at 820 °C in the flowing oxygen. The crystal structure, morphology and electrochemical properties of the precursors and final products were investigated by using X–ray diffractometry, scanning electron microscopy, charge–discharge test and C–V method. In the voltage ranges of 2.8–4.3, 4.4 and 4.5 V, the initial discharge capacities of LiNi0.6Co0.2Mn0.2O2 at 1 C rate were 172.1, 177.9 and 182.5 mAh g−1, respectively, while the corresponding discharge capacity retention ratios after 100 cycles were 94.3%, 90.7% and 85.4%. For elevated temperature operation (60 °C), the resulted capacity was as high as 196.9mAh g−1 in the voltage range of 2.8–4.3 V and retained 89.7% after 100 cycles.

Micro-spherical particle of Ni–Mn–Co alloy was synthesized by powder metallurgy pulverization (PMP) method with Ni, Co and Mn metal as raw materials. Then spherical and dense LiNi 1/3 Mn 1/3 Co 1/3 O 2 particle with well-ordered layered structure is obtained by calcining the oxide of Ni–Mn–Co alloy and Li 2 CO 3 . The as-prepared material was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical tests. LiNi 1/3 Mn 1/3 Co 1/3 O 2 prepared here indicated an initial discharge capacity of 164.4 mAh g −1 at 0.1 C rate within the voltage range of 2.8–4.3 V. The novel method showed high efficiency and environmental friendly for industrialization.

A fast precipitation method is adopted for synthesis of nano-MnPO4·H2O, with MnSO4·H2O, H3PO4, NH4NO3 and NaOH as raw materials. MnPO4·H2O precipitate is characterized by XRD (X-ray diffraction) and SEM (scanning electron microscope). Fine-sized, well-crystallized, carbon-coated LiMnPO4/C nano-composites are obtained by using mechanochemical activation assisted carbothermal reduction route from as-prepared MnPO4·H2O, Li2CO3 and PVA (polyvinyl alcohol). The effect of calcination temperature on the structure and properties of obtained materials is investigated by XRD, SEM, TEM (transmission electron microscopy) and electrochemical measurements. The in situ 6.8 wt% carbon coated LiMnPO4/C displays discharge specific capacity of 124 mAh g−1 at 0.05 C rate and 108 mAh g−1 at 1 C rate. The capacity retention is nearly 100% after 20 cycles at 1 C rate. This mechanochemical activation assisted precipitation technique is a facile approach for the fabrication of LiMnPO4 cathode materials.

Co, Mn and Mg co-doped lithium nickel oxides of the nominal composition LiNi0.9Co0.1−x[Mn1/2Mg1/2]xO2 (x = 0.00, 0.02, 0.04, 0.06) are synthesized by a co-precipitation technique and solid state route. XPS results reveal that the oxidation states of Ni, Co, Mn and Mg are +3, +3, +4 and +2, respectively. An ordered α-NaFeO2 rock salt structure with R − 3 ¯ m symmetry has been confirmed by XRD. The cation mixing of Li/Ni and occupation of Mg ions have been analyzed by Rieveld refinement. Mg ions distribute between 3b and 3a sites in the crystal. Meanwhile a substantial reduction of cation mixing of Li–Ni has been confirmed by Mn–Mg substitution. Better cycling performance is observed in the compound with high Mn–Mg content compared with LiNi0.9Co0.1O2. Mn–Mg substitution for Co has been shown to suppress the increase of the cell impedance during cycles effectively.

Micro-spherical particle of MnCO 3 has been successfully synthesized in CTAB–C 8 H 18 –C 4 H 9 OH–H 2 O micro-emulsion system. Mn 2 O 3 decomposed from the MnCO 3 is mixed with Li 2 CO 3 and sintered at 800 °C for 12 h, and the pure spinel LiMn 2 O 4 in sub-micrometer size is obtained. The LiMn 2 O 4 has initial discharge specific capacity of 124 mAh g −1 at discharge current of 120 mA g −1 between 3 and 4.2 V, and retains 118 mAh g −1 after 110 cycles. High-rate capability test shows that even at a current density of 16 C, capacity about 103 mAh g −1 is delivered, whose power is 57 times of that at 0.2 C. The capacity loss rate at 55 °C is 0.27% per cycle.

A water quenching (WQ) method was developed to synthesize LiFePO 4 and C-LiFePO 4 . Our results indicate that this synthesis method ensures improved electrochemical activity and small crystal grain size. The synthetic conditions were optimized using orthogonal experiments. The LiFePO 4 sample prepared at the optimized condition showed a maximum discharge capacity of 149.8 mAh g −1 at a C/10 rate. C-LiFePO 4 with a low carbon content of 0.93% and a high discharge specific capacity of 163.8 mAh g −1 has also been obtained using this method. Water quenching treatment shows outstanding improvement of the electrochemical performance of LiFePO 4 .