A critical challenge in the commercialization of layer‐structured Ni‐rich materials is the fast capacity drop and voltage fading due to the interfacial instability and bulk structural degradation of ...the cathodes during battery operation. Herein, with the guidance of theoretical calculations of migration energy difference between La and Ti from the surface to the inside of LiNi0.8Co0.1Mn0.1O2, for the first time, Ti‐doped and La4NiLiO8‐coated LiNi0.8Co0.1Mn0.1O2 cathodes are rationally designed and prepared, via a simple and convenient dual‐modification strategy of synchronous synthesis and in situ modification. Impressively, the dual modified materials show remarkably improved electrochemical performance and largely suppressed voltage fading, even under exertive operational conditions at elevated temperature and under extended cutoff voltage. Further studies reveal that the nanoscale structural degradation on material surfaces and the appearance of intergranular cracks associated with the inconsistent evolution of structural degradation at the particle level can be effectively suppressed by the synergetic effect of the conductive La4NiLiO8 coating layer and the strong TiO bond. The present work demonstrates that our strategy can simultaneously address the two issues with respect to interfacial instability and bulk structural degradation, and it represents a significant progress in the development of advanced cathode materials for high‐performance lithium‐ion batteries.
Ti‐doped and La4NiLiO8‐coated Ni‐rich layered oxide cathodes are synchronously and in situ synthesized with the guidance of theoretical calculations, which exhibit good surficial stability, fast interfacial kinetic behaviors, suppressed inconsistent structural degradation in combination with markedly improved electrochemical performance. This work opens a new avenue of designing simple modification approaches and advanced cathodes for high‐energy lithium‐ion batteries.
The garnet Li
La
Zr
O
(LLZO) has been widely investigated because of its high conductivity, wide electrochemical window, and chemical stability with regards to lithium metal. However, the usual ...preparation process of LLZO requires high-temperature sintering for a long time and a lot of mother powder to compensate for lithium evaporation. In this study submicron Li
La
Zr
Nb
O
(LLZNO) powder-which has a stable cubic phase and high sintering activity-was prepared using the conventional solid-state reaction and the attrition milling process, and Li stoichiometric LLZNO ceramics were obtained by sintering this powder-which is difficult to control under high sintering temperatures and when sintered for a long time-at a relatively low temperature or for a short amount of time. The particle-size distribution, phase structure, microstructure, distribution of elements, total ionic conductivity, relative density, and activation energy of the submicron LLZNO powder and the LLZNO ceramics were tested and analyzed using laser diffraction particle-size analyzer (LD), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Electrochemical Impedance Spectroscopy (EIS), and the Archimedean method. The total ionic conductivity of samples sintered at 1200 °C for 30 min was 5.09 × 10
S·cm
, the activation energy was 0.311 eV, and the relative density was 87.3%. When the samples were sintered at 1150 °C for 60 min the total ionic conductivity was 3.49 × 10
S·cm
, the activation energy was 0.316 eV, and the relative density was 90.4%. At the same time, quasi-solid-state batteries were assembled with LiMn
O
as the positive electrode and submicron LLZNO powder as the solid-state electrolyte. After 50 cycles, the discharge specific capacity was 105.5 mAh/g and the columbic efficiency was above 95%.
Lithium-rich layered oxide is one of the most promising candidates for the next-generation cathode materials of high-energy-density lithium ion batteries because of its high discharge capacity. ...However, it has the disadvantages of uneven composition, voltage decay, and poor rate capacity, which are closely related to the preparation method. Here, 0.5Li
MnO
·0.5LiMn
Ni
Co
O
was successfully prepared by sol-gel and oxalate co-precipitation methods. A systematic analysis of the materials shows that the 0.5Li
MnO
·0.5LiMn
Ni
Co
O
prepared by the oxalic acid co-precipitation method had the most stable layered structure and the best electrochemical performance. The initial discharge specific capacity was 261.6 mAh·g
at 0.05 C, and the discharge specific capacity was 138 mAh·g
at 5 C. The voltage decay was only 210 mV, and the capacity retention was 94.2% after 100 cycles at 1 C. The suppression of voltage decay can be attributed to the high nickel content and uniform element distribution. In addition, tightly packed porous spheres help to reduce lithium ion diffusion energy and improve the stability of the layered structure, thereby improving cycle stability and rate capacity. This conclusion provides a reference for designing high-energy-density lithium-ion batteries.
Although LiNi
Co
Mn
O
is attracting increasing attention on account of its high specific capacity, the moderate cycle lifetime still hinders its large-scale commercialization applications. Herein, ...the Ti-doped LiNi
Co
Mn
O
compounds are successfully synthesized. The Li(Ni
Co
Mn
)
Ti
O
sample exhibits the best electrochemical performance. Under the voltage range of 2.7
4.3 V, it maintains a reversible capacity of 151.01 mAh·g
with the capacity retention of 83.98% after 200 cycles at 1 C. Electrochemical impedance spectroscopy (EIS) and differential capacity profiles during prolonged cycling demonstrate that the Ti doping could enhance both the abilities of electronic transition and Li ion diffusion. More importantly, Ti doping can also improve the reversibility of the H2-H3 phase transitions during charge-discharge cycles, thus improving the electrochemical performance of Ni-rich cathodes.
Polydimethylsiloxane (PDMS) has been widely used in flexible electronics, soft robotics, and bioelectronics. However, the fabrication of PDMS‐based devices has mostly relied on conventional ...approaches, such as casting and molding, thereby limiting their potential. Here we fabricate PDMS‐based composites with programmable microstructures by direct ink writing and realize their practical functionalities of four‐dimensional (4D) printing. The mechanical, thermomechanical and magnetic properties of the three‐dimensional‐printed composites can be well tailored by using carbon, metal, or ceramic functional fillers. By taking advantage of the printable, flexible, and magnetic PDMS composites, we demonstrate new practical functionalities of 4D printing by designing programmable architectures, including magnetic‐field‐driven battery cases and patchworks, as well as arbitrary morphing ceramic structures. In particular, 4D‐printed batteries are constructed by PDMS‐based battery cases for the first time, which can be actuated via external magnetic field. This study broadens the paradigm of 4D printing for prospective applications, such as implant batteries, biomimetic engineering, and customized biomedical devices.
Three‐dimensional printable polydimethylsiloxane (PDMS)‐based composites with carbon, metal, and ceramic functional fillers are developed. The programmable architectures are designed by printing the PDMS‐based composites and demonstrated to present new practical functionalities of four‐dimensional (4D) printing, including magnetic‐field‐driven 4D‐printed batteries and patchwork with flip motion underwater, as well as arbitrary morphing ceramic architectures.
The high energy density lithium ion batteries are being pursued because of their extensive application in electric vehicles with a large mileage and storage energy station with a long life. So, ...increasing the charge voltage becomes a strategy to improve the energy density. But it brings some harmful to the structural stability. In order to find the equilibrium between capacity and structure stability, the K and Cl co-doped LiNi
0.5
Co
0.2
Mn
0.3
O
2
(NCM) cathode materials are designed based on defect theory, and prepared by solid state reaction. The structure is investigated by means of X-ray diffraction (XRD), rietveld refinements, scanning electron microscope (SEM), XPS, EDS mapping and transmission electron microscope (TEM). Electrochemical properties are measured through electrochemical impedance spectroscopy (EIS), cyclic voltammogram curves (CV), charge/discharge tests. The results of XRD, EDS mapping, and XPS show that K and Cl are successfully incorporated into the lattice of NCM cathode materials. Rietveld refinements along with TEM analysis manifest K and Cl co-doping can effectively reduce cation mixing and make the layered structure more complete. After 100 cycles at 1 C, the K and Cl co-doped NCM retains a more integrated layered structure compared to the pristine NCM. It indicates the co-doping can effectively strengthen the layer structure and suppress the phase transition to some degree during repeated charge and discharge process. Through CV curves, it can be found that K and Cl co-doping can weaken the electrode polarization and improve the electrochemical performance. Electrochemical tests show that the discharge capacity of Li
0.99
K
0.01
(Ni
0.5
Co
0.3
Mn
0.2
)O
1.99
Cl
0.01
(KCl-NCM) are far higher than NCM at 5 C, and capacity retention reaches 78.1% after 100 cycles at 1 C. EIS measurement indicates that doping K and Cl contributes to the better lithium ion diffusion and the lower charge transfer resistance.
Nowadays, Li–CO
2
batteries have attracted enormous interests due to their high energy density for integrated energy storage and conversion devices, superiorities of capturing and converting CO
2
. ...Nevertheless, the actual application of Li–CO
2
batteries is hindered attributed to excessive overpotential and poor lifespan. In the past decades, catalysts have been employed in the Li–CO
2
batteries and been demonstrated to reduce the decomposition potential of the as-formed Li
2
CO
3
during charge process with high efficiency. However, as a representative of promising catalysts, the high costs of noble metals limit the further development, which gives rise to the exploration of catalysts with high efficiency and low cost. In this work, we prepared a K
+
doped MnO
2
nanowires networks with three-dimensional interconnections (3D KMO NWs) catalyst through a simple hydrothermal method. The interconnected 3D nanowires network catalysts could accelerate the Li ions diffusion, CO
2
transfer and the decomposition of discharge products Li
2
CO
3
. It is found that high content of K
+
doping can promote the diffusion of ions, electrons and CO
2
in the MnO
2
air cathode, and promote the octahedral effect of MnO
6
, stabilize the structure of MnO
2
hosts, and improve the catalytic activity of CO
2
. Therefore, it shows a high total discharge capacity of 9,043 mAh g
−1
, a low overpotential of 1.25 V, and a longer cycle performance.
Nitrogen-doped porous carbon materials (NPCMs) are usually obtained by carbonization of complicated nitrogen-containing polymers in the presence of template or physical/chemical activation of the ...as-synthesized carbon materials. Herein we reported the facile synthesis of NPCMs by direct carbonization of a series of furfuryl amine (FA)-based protic salts (FAX, X = NTf
, HSO
, H
PO
, CF
SO
, BF
, NO
, Cl) without any templates, tedious synthetic steps and other advanced techniques. The thermal decomposition of precursors and structure, elemental composition, surface atomic configuration, and porosity of carbons have been carefully investigated by thermogravimetric analysis (TGA), X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectroscopy (XPS), combustion elemental analysis, energy-dispersive spectrometry, and nitrogen isotherm adsorption. Different from the parent amine FA that was evaporated below 130°C and no carbon was finally obtained, it was found that all the prepared protic precursors yield NPCMs. These carbon materials were found to exhibit anion structure- dependent carbon yield, chemical composition, and porous structure. The obtained NPCMs can be further exploited as adsorbents for dye removal and decoloration. Among all NPCMs, FAH
PO
-derived carbon owing to its high surface area and special pore structure exhibits the highest adsorption capacities toward both Methylene blue and Rhodamine B.
Li2MnO3-coated LiNi0.5Co0.2Mn0.3O2 materials are successfully synthesized by sol–gel method. The effects of various pH values and Li2MnO3 contents on the structural and electrochemical properties of ...LiNi0.5Co0.2Mn0.3O2 cathode materials are systematically investigated, respectively. Scanning electron microscope, transmission electron microscope and energy dispersive spectrometer confirm that the particles of LiNi0.5Co0.2Mn0.3O2 are completely coated by crystalline Li2MnO3 phase. Electrochemical tests show that suitable Li2MnO3-coated samples exhibit higher rate capacity and better cycling performance than those of the pristine one. This improvement can be attributed to the synergetic contribution from the neutral pH value and appropriate Li2MnO3 amount. The neutral pH environment can protect the core material from damaging during the coating process and is conducive to relieving the rapid moisture uptaking problem of LiNi0.5Co0.2Mn0.3O2. While, suitable Li2MnO3 coating can protect the bulk from directly contacting the electrolyte and offer a fast Li+ diffusion path at the interface of bulk and electrolyte.
The 5% Li2MnO3-coated LiNi0.5Co0.2Mn0.3O2 sample, modified at pH 6, exhibits a conformal and amorphous coating layer before calcination. After been sintered at 880 °C for 5 h, the sample shows Li2MnO3 crystalline surface, as well as superior electrochemical performance. Display omitted
•Li2MnO3-coated LiNi0.5Co0.2Mn0.3O2 is prepared by sol–gel method.•Neutral pH environment can protect NMC from damaging during the coating process.•Li2MnO3 coating enhances the pristine at high cyclability and rate properties.•Suitable Li2MnO3 modification results in better Li+ diffusion coefficient.•The 5% Li2MnO3-coated sample exhibits the best electrochemical performance.
Heteroatom-doped meso/micro-porous carbon materials are conventionally produced by harsh carbonization under an inert atmosphere involving specific precursors, hard/soft templates, and ...heteroatom-containing agents. Herein, we report a facile synthesis of N and O co-doped meso/micro-porous carbon (NOMC) by template-free carbonization of a small-molecule precursor in a semi-closed system. The semi-closed carbonizaiton process yields hydrophilic NOMCs with large surface area in a high yield. The porous structure as well as the elemental composition of NOMCs can be modulated by changing the holding time at a particular temperature. NOMCs as metal-free heterogeneous catalysts can selectively oxidize benzyl alcohol and its derivatives into aldehydes/ketones with > 85% conversion in aqueous solution, which is much higher than that of the control sample obtained in tube furnace (21% conversion), mainly due to their high N content, high percentage of pyridinic N, and large surface area. The presence of O-containing moieties also helps to improve the hydrophilicity and dispersion ability of catalysts and thus facilitates the mass transfer process during aqueous oxidation. The NOMC catalysts also dispayed excellent activity for a wide range of substrates with a selectivity of > 99%.
Without any inert gas protection, highly porous NOMCs are facilely obtained by direct and template-free carbonization of a single precursor in a muffle furnace under air atmosphere, which can be used as efficient catalysts for selective aqueous oxidation of alcohols. Display omitted
•NOMCs are obtained by template-free carbonization of a single precursor in a semi-closed system, without any inert gas protection.•The NOMCs can be used as metal-free catalysts for highly selective aqueous oxidation of alcohols under mild conditions.•The NOMCs can be easily recycled and reused.
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