Dual carbon-confined Na2MnPO4F nanoparticles as a superior cathode for rechargeable sodium-ion battery

Na₂MnPO₄F has drawn worldwide attention as cathode materials for sodium-ion batteries with great promise due to its high theoretical capacity (124 mAh g⁻¹) and working voltage plateau (3.6 V). Unfortunately, its electrochemical performances are largely limited by the intrinsic low electron conductivity and sluggish diffusion of Na⁺. Herein, a reduced graphite oxide nanosheets and nano-carbon co-modified Na₂MnPO₄F nanocomposite is prepared via a simple hydrothermal method. And the composite possesses a three-dimensional “pellets-on-sheets” structure, in which core-shell structured nanoparticles (Na₂MnPO₄F nanoparticles coated by carbon coating layers) are uniformly anchored on the surface of well-dispersed reduced graphite oxide nanosheets. Such unique structure is favorable for fast Na⁺ and electron transports and supplies sufficient active sites for Na⁺ insertion. As the cathode of sodium-ion battery, the as-prepared dual carbon-modified Na₂MnPO₄F composite exhibits a super discharge capacity of 122 mAh g⁻¹ at 0.05 C and high rate-performance (42 mAh g⁻¹ at 2 C) as well as long cycle performance (77% capacity retention after 200 cycles at 0.1 C). Meanwhile, it presents two obvious potential platforms of about 3.7 V and 3.5 V during the charge and discharge process, respectively, revealing its potential applications in high energy density batteries.     

A facile strategy for recovering spent LiFePO4 and LiMn2O4 cathode materials to produce high performance LiMnxFe1-xPO4/C cathode materials

To successfully recycle spent LiFePO₄ and LiMn₂O₄ batteries and simultaneously produce high performances nano-LiMn_xFe_1-xPO₄/C powders, a mechanical activation-assisted method was effectively applied in the recycling process. The technique consists of the separation and purification of spent cathode materials, high-energy mechanical mixing of raw materials and a commonly used heat treatment processes. The structural and morphological characterization results indicate that nano-sized LiMn_xFe_1-xPO₄/C composites with uniform amorphous carbon coatings were successfully synthesized from spent LiFePO₄ and LiMn₂O₄ batteries. The electrochemical performance testing results show that the recovered nano-LiMn_xFe_1-xPO₄/C cathodes possess promising Li-ion storage properties. LiMn_0.5Fe_0.5PO₄/C displays high capacities of 143.2, 138.1, and 127.6 mAh g⁻¹ at 0.1, 1, and 2C rates, respectively. The obtained cathodes also show outstanding cycling stabilities of 98.47% and 97.58% for LiMn_0.5Fe_0.5PO₄/C and LiMn_0.8Fe_0.2PO₄/C after 100 cycles, respectively. This work indicates that recycling spent LiFePO₄ and LiMn₂O₄ to produce high-performance LiMn_xFe_1-xPO₄/C is a promising strategy for recycling spent LiFePO₄ and LiMn₂O₄ based lithium ion batteries (LIBs) in an efficient and environmentally friendly manner.     

Pyrometallurgically regenerated LiMn2O4 cathode scrap material and its electrochemical properties

Recycling cathode materials from lithium-ion battery scraps can play a significant role in reducing environmental contamination and resource depletion. In this study, we employed pyrometallurgical techniques to regenerate LiMn₂O₄ cathode materials from recovered cathode scraps. First, the binder was removed under optimal conditions by a heating and stirring method to maximize the dissolution rate of the cathode scrap materials. Next, inductively coupled plasma spectroscopy was used to define the Li and Mn contents, and finally, the LiMn₂O₄ cathode material was regenerated by a pyrometallurgical method. After calcination under the optimum conditions of 500 °C for 12 h, electrochemical performance testing revealed obvious charge and discharge platforms in the charge/discharge curves; further, a high first-cycle discharge capacity was observed at 136.6 mAh·g^-1 (3.0–4.3 V and 0.1 C), which decreased to 93 mAh·g^-1 after 50 cycles. This process is low-cost and environmentally friendly, with the potential for recovering other cathode scrap materials.     

Comparison of structure and electrochemistry of Al- and Fe-doped LiNi1/3Co1/3Mn1/3O2

LiNi_1/3Co_1/3−xM_xMn_1/3O₂ (M = Fe and Al; x = 0, 1/20, 1/9 and 1/6) have been synthesized by firing the co-precipitates of metal hydroxides. The impacts of Fe and Al doping on the structure and electrochemical performances of LiNi_1/3Co_1/3Mn_1/3O₂ are compared by means of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and galvanostatic charge/discharge test as cathode materials for lithium ion batteries. These materials keep the same layered structure as the LiNi_1/3Co_1/3Mn_1/3O₂ host. It is found that Fe- and Al-doped LiNi_1/3Co_1/3Mn_1/3O₂ show different characteristics in lattice parameter and cycling voltage plateau with increasing dopant dose. More interestingly, low Al doping (x < 1/20) improves the structural stability while Fe doping does not have such effect even at low Fe content.     

Porous polythiophene as a cathode material for lithium batteries with high capacity and good cycling stability

Polythiophene (PTh) has been synthesized by chemical oxidative polymerization and used as an active cathode material in lithium batteries. The lithium batteries are characterized by cyclic voltammetry (CV), galvanostatic charge/discharge cycling and electrochemical impedance spectroscopic studies (EIS). The lithium battery with the PTh cathode exhibits a discharge voltage of 3.7 V compared to Li⁺/Li and excellent electrochemical performance. PTh can provide large discharge capacities above 50 mA h g⁻¹ and good cycle stability at a high current density 900 mA g⁻¹. After 500 cycles, the discharge capacity is maintained at 50.6 mA h g⁻¹. PTh is a promising candidate for high-voltage power sources with excellent electrochemical performance.     

Energy storage capacity investigation of pulsed current formed nano-structured lead dioxide

An electro-deposition method was used for the preparation of nano-structured lead dioxide. The lead dioxide films prepared were used as positive electrodes of lead acid batteries. Different parameters such as pulse time (t_on), pulse height, and relaxation time (t_off) were optimized to obtain higher capacity. Depend on the pulse conditions, a range of different morphologies of various porosities and connectivity was obtained. The resulting batteries were discharged to a cut off voltage of 1.75 V by a pulsed current method. The energy storage ability of the prepared lead acid batteries shows a close relation with the morphology of cathode materials. Maximum capacity was observed when pulse and relaxation time was equal to 0.1 and 5 s, respectively, at a current density of 25 mA cm⁻². A change in morphology of lead dioxide from aggregated globular structure to nanofiber was occurred. It was found that the high surface area as well as high connectivity between particles resulted in increased discharge capacity. Analysis of electrochemical impedance spectroscopy (EIS) data revealed that the charge transfer resistance is decreased by a change in morphology from bulk globular to nanofiber as the energy storage test showed. The time dependence of impedance behavior of a sample prepared at t_on = 0.1 s and t_off = 5 s at 25 mA cm⁻² was investigated and the results are discussed.     

Electrochemical performance of chemically synthesized oligo-indole as a positive electrode for lithium rechargeable batteries

Indole monomer was chemically polymerized to produce polyindole (PI) powder for use as a positive electrode material for lithium rechargeable batteries. Although the PI obtained was an oligomer with a low molecular weight corresponding to just 3 indole units, its electrochemical properties exhibited high d.c. electric conductivity comparable to that of the highly conducting polyaniline-LiPF₆ or LiAsF₆. A charge separation mechanism was also suggested to describe charge/discharge behavior of the oligo-indole (OI) protonated and/or lithiated in the Li||OI battery. Moreover, the lithium rechargeable battery adopting the OI as a positive electrode showed good cycleability with a discharge capacity of ∼55 mAh g⁻¹, which did not decay until after more than 100 cycles.     

Nano-CaCO3 templated mesoporous carbon as anode material for Li-ion batteries

Mesoporous hard carbon is obtained by pyrolyzing a mixture of sucrose and nanoscaled calcium carbonate (CaCO₃) particles. The microstructure of the carbon is characterized by N₂ adsorption/desorption, Hg porosimetry, field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Raman spectroscopy. The electrochemical performances of the carbon as an anode material for lithium ion batteries are evaluated by galvanostatic charge/discharge and cyclic voltammetry tests. It is shown that this mesoporous carbon possesses high capacity, good cycling performance and rate capability, indicating the promising application of nano-CaCO₃ particle as template in massive fabrication of mesoporous carbon anode materials for lithium ion batteries.     

Natural fibers and zinc hydroxystannate 3D microspheres based composite paper sheets for modern bendable energy storage application

For modern high-tech flexible energy storage devices, it becomes important to synthesize micro-/nanostructures as per the required shape and morphology with superior physical and electro-active characteristics. This work shares the fabrication and characterization of ZnSn(OH)₆ (Zinc hydroxystannate [ZHS]) prepared by facile microwave-assisted technique and furthermore converted into flexible sheets by employing lignocelluloses (LC) known as natural fibers, collected from Carica papaya leaf petiole as a substrate to provide the flexible matrix. X-ray diffraction measurements confirm the successful crystalline structure of ZHS. Scanning electron microscopy and transmission electron microscopy showed the solid spherical structure of ZHS microspheres. Fourier transform infrared spectrometry and Raman spectroscopy confirmed the composite formation of ZHS and LC-based composite sheets (ZHS/LC sheets). Electrochemical measurements that is, cyclic voltammetry (CV), Galvanostatic charge/discharge, and electrochemical impedance (EIS) spectroscopy revealed the electroactive behavior of ZHS/LC paper sheets as working electrode for energy storage applications. CV measurements revealed the specific capacitance of 100 F/g and EIS measurements confirmed the decrease in the resistance of LC fiber after the growth of ZHS microspheres. Presented flexible ZHS based paper sheets will be highly feasible for the modern bendable/flexible/disposable energy storage applications.     

湿法冶金回收废旧锂电池正极材料的研究进展

全球电动汽车和智能手机市场的逐年扩大,直接促进了全球锂离子电池市场规模的增加,锂离子电池的回收与再利用具有重要的经济和社会价值。本文综述了废旧锂离子电池正极材料的主要回收方法,包括梯次利用法、火法冶金法、湿法冶金法和直接回收法,重点综述了湿法冶金法的工艺流程和重要步骤,介绍了机械处理与正极材料浸出、浸出液的回收利用、有价值金属产物的再生合成的研究进展,最后对湿法冶金综合回收废旧锂电池正极材料的未来发展进行了展望。     

High performance NASICON ceramic electrolytes produced by tape-casting and low temperature hot-pressing: Towards sustainable all-solid-state sodium batteries operating at room temperature

In this work, we propose a processing methodology, based on the combination of tape-casting and low temperature hot-pressing, to develop ceramic NASICON electrolytes with formula Na_3.16Zr_1.84Y_0.16Si₂PO₁₂ towards the attainment of solid-state sodium batteries operating at room temperature. Solid-state NASICON electrolytes with very good mechanical properties and high ionic conductivity are successfully tested in terms of electrochemical behavior by using the cell configuration: Na/NASICON/FePO₄. Following charge-discharge cycles, an unusual redox pair of FePO₄ is found, indicating that the all-solid-state battery with the Na metal anode may be effectively operated at room temperature. At a charge/discharge current density of C/20, the solid-state battery has an initial reversible discharge capacity of 85 mAh/g. Because of its relatively high ionic conductivity and thermostability, when in contact with the Na anode and the FePO₄ cathode, the NASICON ceramic electrolyte is a viable option for attaining reliable, safer and sustainable all-solid-state batteries operating at room temperature.     

锂离子电池低温充放电性能的研究

研究了锂离子电池在不同温度下(室温～-30℃)的充放电性能。结果表明,随着温度的降低,锂离子电池的充电性能和放电性能均显著降低。当温度降至-30℃时,电池的放电容量为室温放电容量的87.0%,放电平均电压比室温时降低了0.598V;锂离子电流的恒流充电容量仅为充电总容量的14%,恒压充电时间增长。结合电化学阻抗图谱,对锂离子电池低温性能的主要影响因素进行了研究。     

Solution-Combustion Synthesis of LiNi<Subscript>1/3</Subscript>Co<Subscript>1/3</Subscript>Mn<Subscript>1/3</Subscript>O<Subscript>2</Subscript> as a Cathode Material for Lithium-Ion Batteries

A cathode material for lithium-ion batteries–LiNi_1/3Co_1/3Mn_1/3O₂–was prepared by solution combustion synthesis and characterized by XRD, SEM, and galvanostatic charge/discharge cycling. The sample calcined at 950°C for 10 h showed best charge/discharge performance. An initial discharge capacity (C) of 150.5 mA h g^–1 retained 95.7% of its value after 75 charge/discharge cycles at I_c = 14 mA g^–1 (0.2C rate), I_d = 70 mA g^–1 (0.5C rate).     

Vacancy-enhanced cycle life and electrochemical performance of lithium-rich layered oxide Li2RuO3

Vacancy plays an important role in charge/discharge processes of solid-state lithium batteries because the vacancy-induced charge carrier trap and transportation channels effectively facilitate the diffusion of Li ion. Although lithium-rich layered oxide Li₂TMO₃ is a promising electrode material, it's vacancy mechanism remains unclear. In particular, the role of vacancy in the cycle life and electrochemical performance of Li₂TMO₃ is unknown. Here, we report on the volume variation (ΔV), average open circuit voltage (V_oc) and electronic structure of Li₂RuO₃ layered oxide with various vacancies. Compared to Li_-va vacancy, O_-va (4.74 V) and Ru_-va (4.60 V) vacancies enhance the V_oc of Li₂RuO₃ (4.46 V) because O_-va and Ru_-va vacancies induced charge carrier traps improve the charge overlaps between the conduction band and valence band near the Fermi level. In particular, O_-va vacancy is more thermodynamically stable than that of the other vacancies. Whether the perfect vacancy or vacancies after Li extraction, the calculated ΔV of O_-va vacancy is smaller than that of the other vacancies. Therefore, we believe that O_-va vacancy can improve the cycle life and electrochemical performance of Li₂TMO₃ layered oxides lithium batteries.     

Ca3(PO4)2 coating of spherical Ni(OH)2 cathode materials for Ni-MH batteries at elevated temperature

Calcium phosphate was used for surface modification of spherical nickel hydroxide to improve its high temperature performance at the first time due to its low cost. The Ca₃(PO₄)₂ and Co(OH)₂ coated nickel hydroxides were prepared by precipitation of Ca₃(PO₄)₂ on the surface of spherical nickel hydroxide, followed by precipitation of Co(OH)₂ on its surface. The optimum coating content of calcium was around 2% (atomic concentration) to obtain high discharge capacity both at 25 and 60 °C. It was shown that the discharge capacity of nickel hydroxide at higher temperatures was improved by coating of Ca₃(PO₄)₂ and cobalt hydroxide. The high temperature performances of the sealed AA-sized nickel-metal hydride (Ni-MH) batteries using Ca/Co coated nickel hydroxide as positive electrodes were carried out, showing much better than those using uncoated or only Co(OH)₂ coated nickel hydroxide electrodes. The charge acceptance of the battery using 2% Ca and 2% Co coated nickel hydroxide reached 81% at 60 °C, where the charge acceptances for uncoated and only Co(OH)₂ coated nickel hydroxide were only 42 and 48%, respectively. It has shown that the Ca/Co coating is an effective way to improve the high temperature performance of nickel hydroxide for nickel-metal hydride batteries. It is a promising cathode material of Ni-MH batteries for EV applications due to the cost.     

Preparation of spinel LiMn2O4 cathode material from used zinc-carbon and lithium-ion batteries

Due to the progressive shortage of primary resources and growing environmental concerns over industrial and household residues, proper management of electronic wastes is of great importance in addressing sustainability issues. Spent batteries are considered as important secondary sources of their constituting components. In this study, the co-recycling of used zinc-carbon and lithium-ion batteries was performed aiming at the recovery of their manganese and lithium contents as compounds which can be used as precursors for the synthesis of spinel LiMn₂O₄. Manganese was recovered in the form of amorphous, submicron, spherical nodules of MnO₂ after acid leaching of zinc-carbon battery pastes. Lithium was obtained from nickel-manganese-cobalt (NMC) batteries as its monohydrate oxalate (C₂HLiO₄.H₂O) through selective leaching in oxalic acid followed by crystallization. Lithium carbonate was also prepared by subsequent calcination of the oxalate. The synthesis of LiMn₂O₄ spinel cathode was investigated using the reclaimed Li- and Mn-containing compounds via solid-state synthesis method. The effect of such parameters as type of precursors (C₂HLiO₄.H₂O/Li₂CO₃ with Mn₂O₃/MnO₂), temperature (750, 800, and 850 °C), and time (8 and 10 h) on the synthesis of LiMn₂O₄ was investigated. The products were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The crystallographic parameters from XRD analysis were used to predict the electrochemical behavior of the synthesized cathode materials. Based on these, the spinel powder synthesized at 850°C?10h from Li₂CO₃?Mn₂O₃ starting mixture was determined as the cathode material with the best electrochemical properties among the synthesized samples. The galvanostatic charge/discharge evaluation within the voltage range of 2.5–4.3 V showed the specific capacity of the 850°C-10 h sample to be 127.87 mAhg^?1.     

Polyterthiophene/CNT composite as a cathode material for lithium batteries employing an ionic liquid electrolyte

A polyterthiophene (PTTh)/multi-walled carbon nanotube (CNT) composite was synthesised by in situ chemical polymerisation and used as an active cathode material in lithium cells assembled with an ionic liquid (IL) or conventional liquid electrolyte, LiBF₄/EC-DMC-DEC. The IL electrolyte consisted of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF₄) containing LiBF₄ and a small amount of vinylene carbonate (VC). The lithium cells were characterised by cyclic voltammetry (CV) and galvanostatic charge/discharge cycling. The specific capacity of the cells with IL and conventional liquid electrolytes after the 1st cycle was 50 and 47 mAh g⁻¹ (based on PTTh weight), respectively at the C/5 rate. The capacity retention after the 100th cycle was 78% and 53%, respectively. The lithium cell assembled with a PTTh/CNT composite cathode and a non-flammable IL electrolyte exhibited a mean discharge voltage of 3.8 V vs Li⁺/Li and is a promising candidate for high-voltage power sources with enhanced safety.     

Hydrothermal synthesis of carbon-coated lithium vanadium phosphate

A novel hydrothermal synthesis was developed to prepare carbon-coated lithium vanadium phosphate (Li₃V₂(PO₄)₃) powders to be used as cathode material for Li-ion batteries. The structural, morphological and electrochemical properties were investigated by means of X-ray powder diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and constant current charge-discharge cycling. This material exhibits high initial discharge capacity of 178, 173 and 172 mAh g⁻¹ at 0.1, 0.2 and 0.5 C between 3.0 and 4.8 V, respectively. Moreover, it displays good fast rate performance, which discharge capacities of 136, 132 and 127 mAh g⁻¹ can be delivered after 100 cycles between 3.0 and 4.8 V versus Li at a different rate of 1, 2 and 5 C, respectively. For comparison, the electrochemical properties of carbon-coated lithium vanadium phosphate prepared by traditional solid-state reaction (SSR) method are also studied.     

Study on capacity fade factors of lithium secondary batteries using LiNi0.7Co0.3O2 and graphite-coke hybrid carbon

In our previous work, 10 Wh-class (30650 type) lithium secondary batteries, which were fabricated with LiNi_0.7Co_0.3O₂ positive electrodes and graphite-coke hybrid carbon negative electrodes, showed an excellent cycle performance of 2350 cycles at a 70% state of charge charge-discharge cycle test. However, this cycle performance is insufficient for dispersed energy storage systems, such as home use load leveling systems. In order to clarify the capacity fade factors of the cell, we focused our investigation on the ability discharge capacity of the positive and negative electrodes after 2350 cycles. Although the cell capacity deteriorated to 70% of its initial capacity after 2350 cycles, it was confirmed that the LiNi_0.7Co_0.3O₂ positive electrode and graphite-coke hybrid negative electrode after 2350 cycles still have sufficient ability discharge capacity of 86 and 92% of their initial capacity, respectively. Accompanied by the result for a composition analysis of the positive electrode material by inductively coupled plasma (ICP) spectroscopy and atomic absorption spectrometry (AAS), electrochemical active lithium decreased and the Li_xNi_0.7Co_0.3O₂ positive electrode could be charged-discharged in a narrow range of between x=0.41 and 0.66 in the battery, although it had enough ability discharge capacity that can use between x=0.36 and 0.87. It is predicted that solid electrolyte interface formation by electrolyte decomposition on the carbon negative electrode during the charge-discharge cycle test is a main factor of the decrease of electrochemical active lithium.     

ZnIn2S4: A promising anode material with high electrochemical performance for sodium-ion batteries

In this study, ZnIn₂S₄ (B-ZIS) and ZnIn₂S₄/C (S-ZIS) composites anode are synthesized using hydrothermal method and followed by ball-milling process. The initial discharge/charge capacities for bare ZnIn₂S₄ (B-ZIS) are 524 and 378 mAh g⁻¹ under a current density of 1 A g⁻¹, which suffers from gradually capacity fading. To improve its cycle stability, high-energy ball-milling process (HEBM) with carbon black is applied to fabricate S-ZIS spherical particles. The as-obtained composite anode exhibits enhanced electrochemical performances not only on cycle stability, but also reversible capacity. The discharge and charge capacity of S-ZIS approach to 823 and 679 mAh g⁻¹ at the first cycle and retain 468 and 459 mAh g⁻¹ after 500 cycles at the high current density of 1 A g⁻¹. Furthermore, ex situ X-ray diffraction (XRD) and ex situ X-ray photoelectron spectroscopy (XPS) techniques are used to monitor the evaluation of crystal structure of B-ZIS during charge and discharge processes. The results indicate that the metallic Zn and In were observed at low potential voltage during sodiation process and successfully converted back to spinel phase at above 0.5 V. The presence of high reversibility nature of B-ZIS may leads to the superior cycling and excellent rate capability of S-ZIS which makes ZnIn₂S₄ a potential anode material of sodium ion batteries.