Low-temperature synthesis of a green material for lithium-ion batteries cathode

Abstract

Battery technology is an important anthropogenic source of the heavy metals which are highly threatening to human health. A category of rechargeable lithium batteries that is of great interest is the set of batteries where the cathode material is a lithium iron phosphate (LiFePO₄). LiFePO₄ is an environmentally friendly and safe lithium-ion battery cathode material, but it has a key limitation, and that is its extremely low-electronic conductivity, a problem that can be greatly overcome by zinc-doping LiFePO₄. For the first time to our knowledge, a low-temperature method, that is advantageous both economically and technologically, for the synthesis of a zinc-doped LiFePO₄ is presented. Since the method appears to be applicable for synthesizing various zinc-doped LiFePO₄ compounds with the general formula LiFe_1?x Zn _x PO₄ (0<x<1), it is very promising for the production of a green cathode material for lithium-ion batteries.     

Mechanical densification synthesis of single-crystalline Ni-rich cathode for high-energy lithium-ion batteries

The intergranular microcracking in polycrystalline Ni-rich cathode particle is led by anisotropic volume change and stress corrosion along grain boundary, accelerating battery performance decay. Herein, we have suggested a simple but advanced solid-state method that ensures both uniform transition metal distribution and single-crystalline morphology for Ni-rich cathode synthesis without sophisticated coprecipitation. Pelletization-assisted mechanical densification(PAMD) process on solid-state pr...     

Photothermal-assisted fabrication of iron fluoride-graphene composite paper cathodes for high-energy lithium-ion batteries

A facile route that combines co-assembly and photothermal reduction was developed to synthesize free-standing, flexible FeF(3)-graphene papers. The papers contain well-dispersed FeF(3) nanoparticles and open diffusion channels in a porous, electrically conducting network of graphene sheets, and demonstrate promising applications as cathodes in high-energy density Li-ion batteries.     

Oxalic acid-assisted preparation of LiFePO4/C cathode material for lithium-ion batteries

LiFePO₄/C composite is synthesized by oxalic acid-assisted rheological phase method. Fe₂O₃ and LiH₂PO₄ are chosen as the starting materials, sucrose as carbon sources, and oxalic acid as the additive. The crystalline structure and morphology of the products are characterized by X-ray diffraction and field emission scanning electron microscopy. The charge–discharge kinetics of LiFePO₄ electrode is investigated using cyclic voltammetry and electrochemical impedance spectroscopy. It is found that the introduction of appropriate amount of oxalic acid leads to smaller particle sizes, more homogeneous size distribution, and some Fe₂P produced in the final products, resulting in reduced polarization, impedance, and improved Li⁺ ion diffusion coefficient. The best cell performance is delivered by the sample with R = 1.5 (R of the molar ratio of oxalic acid to LiH₂PO₄). Its discharge capacity is 154 mAh g⁻¹ at 0.2 C rate and 120 mAh g⁻¹ at 5.0 C rate. At the same time, it exhibits an excellent cycling stability; no obvious decrease even after 1,000 cycles at 1.0 C rate.     

A Fe-rich sodium iron orthophosphate as cathode material for rechargeable batteries

Phosphate compounds have been intensively investigated as cathode materials for sodium ion batteries. Here we report the synthesis and electrochemical performance of a novel iron-rich sodium iron orthophosphate. This new compound was synthesized by a conventional solid state reaction method, and was found to be electrochemically active, delivering a reversible capacity of 85 mAhg^− 1 at an average voltage of c.a. 3.0 V vs. Na/Na⁺. Besides, the desodiated phase can be (de)intercalated by lithium ions when assembled into a lithium cell. Our discovery will open up the scope of phosphate family and reveal the importance of off-stoichiometric compounds as cathode materials.     

Environmentally friendly chemical route to vanadium oxide single-crystalline nanobelts as a cathode material for lithium-ion batteries

Orthorhombic V(2)O(5) single-crystalline nanobelts with widths of 100-300 nm, thicknesses of 30-40 nm, and lengths up to tens of micrometers have been synthesized on a large scale in a hydrogen peroxide aqueous solution by an environmentally friendly chemical route. Such nanobelts grow along the direction of [010]. The influence of the reaction time on the crystal structures and morphologies of the resulting products are investigated. A probable dehydration-recrystallization-cleavage mechanism for the formation of V(2)O(5) nanobelts is proposed. The experiments demonstrate that the use of a nanosized belt-like structure can considerably enhance the specific discharge capacity in lithium-ion batteries.     

Electrolytic iron sulfides for thin-layer lithium-ion batteries

Thin-layer electrolytic iron sulfides synthesized on stainless steel substrates were studied in prototype lithium and lithium-ion batteries with an electrolyte composed of ethylene carbonate, dimethyl carbonate, and 1 M LiClO₄. A two-volt lithium-ion system with electrolytic iron sulfide and LiCoO₂ as negative and positive electrodes, respectively, was suggested. The discharge capacity of the prototype system is 350–400 mA h g⁻¹ Fe sulfide.     

Nickel tetrathiooxalate as a cathode material for potassium batteries

We report a nickel tetrathiooxalate (NiTTO) coordination polymer as a cathode material for potassium batteries. In a potential range of 1.3–3.6 V vs. K⁺/K, the specific capacity of the material is 209 mA h g^?1 at a current density of 0.1 A g^?1, which roughly corresponds to the two-electron reduction of polymer repeating units. The charge–discharge mechanisms of NiTTO in potassium cells were examined using operando Raman spectroscopy.     

Effects of long-term fast charging on a layered cathode for lithium-ion batteries

Fast charging, which aims to shorten recharge times to 10–15 min, is crucial for electric vehicles(EVs),but battery capacity usually decays rapidly if batteries are charged under such severe conditions.Revealing the failure mechanism is a prerequisite to improving the charging performance of lithium(Li)-ion batteries. Previous studies have focused less on cathode materials while also mostly focusing on their early changes. Thus, the cumulative effect of long-term fast charging on cathode materia...     

Insight into the reaction mechanism of sulfur chains adjustable polymer cathode for high-loading lithium-organosulfur batteries

Small molecules with adjustable sulfur atoms in the confined structure were acted as precursor for the synthesis of polymer cathodes for lithium-organosulfur batteries.Among them,poly(diallyl tetrasulfide)(PDATtS)delivered a high capacity of 700 mAh g^-1,stable capacity retention of 85%after 300 cycles,high areal capacity~4 m Ah cm^-2 for electrode with up to 10.3 mg cm^-2 loading.New insight into the reaction mechanism of PDATtS electrode that radicals arisen from the homolytic cleavage of S-S bond in PDATtS reacted with Li+to generate thiolates(RSLi)and insoluble lithium sulfides(Li₂S)or lithium disulfide(Li₂S₂)was clearly verified by in-situ UV/Vis spectroscopy,nuclear magnetic resonance(NMR)studies and density-functional theory(DFT)calculations.Therefore,based on the unique reaction mechanism,problems of rapid capacity fading due to the formation of soluble polysulfide intermediates and their serious shuttle effect in conventional lithium-sulfur(Li-S)batteries was totally avoided,realizing the dendrite-free lithium sulfur batteries.This study sets new trends for avenues of further research to advance Li-S battery technologies.     

Mg/Fe site-specific dual-doping to boost the performance of cobalt-free nickle-rich layered oxide cathode for high-energy lithium-ion batteries

Layer-type LiNi_0.9Mn_0.1O₂ is promising to be the primary cathode material for lithium-ion batteries(LIBs)due to its excellent electrochemical performance.Unfortunately,the cathode with high nickel content suffers from severely detrimental structural transformation that causes rapid capacity attenuation.Herein,site-specific dual-doping with Fe and Mg ions is proposed to enhance the structural stability of LiNi_0.9Mn_0.1O₂.The Fe^...     

Intrinsic characteristics of cathode and anode materials for lithium-ion batteries

Fundamental aspects of solving the problem of how the working capacity of lithium-ion batteries in prolonged cycling can be raised and the basic tendencies in the relationship between the intrinsic parameters of active materials of various brands and the electrochemical behavior of anodes and cathodes fabricated from these materials are considered.     

Effects of AgNPs-coating on the electrochemical performance of LiMn2O4 cathode material for lithium-ion batteries

Journal of Solid State Electrochemistry - The Jahn–Teller effect and severe side reactions with liquid electrolyte have been considered as the main obstacles to the further application of...     

Synthesis and electrochemical properties of K-doped LiFePO4/C composite as cathode material for lithium-ion batteries

Li_1 − x K _x FePO₄/C (x = 0, 0.03, 0.05, and 0.07) composites were synthesized at 700 °C in an argon atmosphere by carbon thermal reduction method. Based on X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analysis, the composite was ultrafine sphere-like particles with 100–300 nm size, and the lattice structure of LiFePO₄ was not destroyed by K doping, while the lattice volume was enlarged. The electrochemical properties were investigated by four-point probe conductivity measurements, galvanostatic charge and discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy. The results indicated that the capacity performance at high rate and cyclic stability were improved by doping an appropriate amount of K, which might be ascribed to the fact that the doped K ion expands Li ion diffusion pathway. Among the doped materials, the Li_0.97K_0.03FePO₄/C samples exhibited the best electrochemical activity, with the initial discharge capacity of 153.7 mAh g⁻¹ at 0.1 C and the capacity retention rate of about 92% after 50 cycles at above 1 C, 11% higher than undoped sample. Remarkably, it still showed good cycle retention at a high current rate of 10 C.     

Pb-sandwiched nanoparticles as anode material for lithium-ion batteries

A sandwiched SiC@Pb@C nanocomposite was prepared through a simple ball-milling route and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The SiC@Pb@C nanocomposite exhibits a much improved reversible capacity and cycling life as compared with a bare Pb anode. A reversible volumetric capacity of >1,586 mAh cm⁻³ (207 mAh g⁻¹) can be maintained after 600 cycles of charge and discharge in the potential interval between 0.005 and 1.0 V, which far exceeds those reported previously in the literature. The enhanced electrochemical performance is ascribed to the sandwiched structure in which nanosized Pb particles were anchored in between the rigid SiC core and the outer carbon shell, mitigating the damage done by the large volume change of the Pb interlayer during the alloying/dealloying process.     

Thermal runaway features of 18650 lithium-ion batteries for LiFePO4 cathode material by DSC and VSP2

In view of availability, accountability, and applicability, LiFePO₄ cathode material has been confirmed to be better than LiCoO₂ cathode material. Nevertheless, few related researches were conducted for thermal runaway reaction of the LiFePO₄ batteries. In this study, vent sizing package 2 (VSP2) and differential scanning calorimetry were employed to observe the thermal hazard of 18650 lithium-ion batteries and their content??LiFePO₄ cathode material, which were manufactured by Commercial Battery, Inc. Two states of the batteries were investigated, which was charged to 3.6?V (fully charged) and 4.2?V (overcharged), respectively, and important parameters were obtained, such as self-heating rate (dT?dt ^?1), pressure-rise rate (dP?dt ^?1), and exothermic onset temperature (T ₀). The results showed that T ₀ for fully charged is about 199.94?°C and T _max is about 243.23?°C. The entire battery for LiFePO₄ cathode material is more stable than other lithium-ion batteries, and an entire battery is more dangerous than a single cathode material. For process loss prevention, the data of battery of VSP2 test were applied as reference for design of safer devices.     

Distinctive electrochemical performance of novel Fe-based Li-rich cathode material prepared by molten salt method for lithium-ion batteries

For constructing next-generation lithium-ion batteries with advanced performances,pursuit of highcapacity Li-rich cathodes has caused considerable attention.So far,the low discharge specific capacity and serious capacity fading are strangling the development of Fe-based Li-rich materials.To activate the extra-capacity of Fe-based Li-rich cathode materials,a facile molten salt method is exploited using an alkaline mixture of LiOH–LiNO_3–Li_2O_2 in this work.The prepared Li_(1.09)(Fe_(0.2)Ni_(0.3)Mn_(0.5))_(0.91)O_2 material yields high discharge specific capacity and good cycling stability.The discharge specific capacity shows an upward tendency at 0.1 C.After 60 cycles,a high reversible specific capacity of ～250 m Ah g~(-1)is delivered.The redox of Fe~(3+)/Fe~(4+)and Mn~(3+)/Mn~(4+)are gradually activated during cycling.Notably,the redox reaction of Fe~(2+)/Fe~(3+)can be observed reversibly below 2 V,which is quite different from the material prepared by a traditional co-precipitation method.The stable morphology of fine nanoparticles(100–300 nm)is considered benefiting for the distinctive electrochemical performances of Li_(1.09)(Fe_(0.2)Ni_(0.3)Mn_(0.5))_(0.91)O_2.This study demonstrates that molten salt method is an inexpensive and effective approach to activate the extra capacity of Fe-based Li-rich cathode material for high-performance lithium-ion batteries.     

LiNi0.8Co0.15Al0.05O2 coated by chromium oxide as a cathode material for lithium-ion batteries

Journal of Solid State Electrochemistry - LiNi0.8Co0.15Al0.05O2 (NCA) material was decorated with different contents of Cr2O3 (0.01–2 wt%) via a precipitation technique followed by...     

液相法合成锂离子电池正极材料Li_(1+x)Mn_2O_4

采用柠檬酸络合和溶液浸渍两种方法制备Li1+xMn2 O4正极材料 ,用XRD和BET测试了材料晶体结构和比表面积 ,考察焙烧温度、Li/Mn比、起始原料对产物结构和电化学性能的影响 ,结果表明 ,焙烧温度与Li/Mn比是影响材料电化学性能的关键因素 ,确定了制备Li1+xMn2 O4材料最佳条件为 0≤x≤ 0 .0 5 ,焙烧温度 75 0°C ,所得电池材料首次充放电容量达到 1 2 0mAh/g .循环 5 0次后 ,其充放电容量为 1 1 5mAh/g .