Lithium‐rich layered oxides are promising cathode materials for lithium‐ion batteries and exhibit a high reversible capacity exceeding 250 mAh g−1. However, voltage fade is the major problem that ...needs to be overcome before they can find practical applications. Here, Li1.2Mn0.54Ni0.13Co0.13O2 (LLMO) oxides are subjected to nanoscale LiFePO4 (LFP) surface modification. The resulting materials combine the advantages of both bulk doping and surface coating as the LLMO crystal structure is stabilized through cationic doping, and the LLMO cathode materials are protected from corrosion induced by organic electrolytes. An LLMO cathode modified with 5 wt % LFP (LLMO–LFP5) demonstrated suppressed voltage fade and a discharge capacity of 282.8 mAh g−1 at 0.1 C with a capacity retention of 98.1 % after 120 cycles. Moreover, the nanoscale LFP layers incorporated into the LLMO surfaces can effectively maintain the lithium‐ion and charge transport channels, and the LLMO–LFP5 cathode demonstrated an excellent rate capacity.
Lithium‐rich layered oxides, Li1.2Mn0.54Ni0.13Co0.13O2 (LLMO), were modified with a nanoscale LiFePO4 (LFP) surface according to a facile sol–gel method. This surface modification combines the advantages of bulk doping and surface coating as the LLMO crystal structure is stabilized by cationic doping and the LLMO cathode is protected from corrosion processes induced by organic electrolytes.
Constructing a stable artificial solid-electrolyte interphase has become one of the most effective strategies to overcome the poor reversibility of lithium metal anode, yet the protection role is ...still insufficient at elevated current densities over 10 mA cm
and large areal capacities over 10 mAh cm
. Herein, we propose a dynamic gel with reversible imine groups, which is prepared via a cross linking reaction between flexible dibenzaldehyde-terminated telechelic poly(ethylene glycol) and rigid chitosan, to fabricate a protective layer for Li metal anode. The as-prepared artificial film shows combined merits of high Young's modulus, strong ductility and high ionic conductivity. When the artificial film is fabricated on a lithium metal anode, the thin protective layer shows a dense and uniform surface owing to the interactions between the abundant polar groups and lithium metal. Besides, the polar groups in the artificial film can homogenize the distribution of Li
at the electrode/electrolyte interface. As a result, cycle stability over 3200 h under an areal capacity of 10 mAh cm
and a current density of 10 mA cm
has been obtained for the protected lithium metal anodes. Moreover, cycling stability and rate capability has been also improved in the full cells.
Nanostructured‐alloy‐type anodes have received great interest for high‐performance lithium‐ion batteries (LIBs). However, these anodes experience huge volume fluctuations during repeated ...lithiation/delithiation and are easily pulverized and subsequently form aggregates. Herein, an efficient method to stabilize alloy‐type anodes by creating defects on the surface of the metal oxide support is proposed. As a demonstration, PPy‐encapsulated SnS2 nanosheets supported on defect‐rich TiO2 nanotubes were produced and investigated as an anode material for LIBs. Both experimental results and theoretical calculations demonstrate that defect‐rich TiO2 provides more chemical adhesions to SnS2 and discharge products, compared to defect‐poor TiO2, and then effectively stabilizes the electrode structure. As a result, the composite exhibits an unprecedented cycle stability. This work paves the way to designing durable and active nanostructured‐alloy‐type anodes on oxide supports.
PPy‐encapsulated SnS2 nanosheets strongly anchored onto a hydrogen‐treated TiO2 (H–TiO2) support have been successfully prepared as an anode for LIBs. As demonstrated by first principles, theoretical calculations, and experimental results, the superior binding between SnS2 and the H–TiO2 support via abundant Ti–S bonding, which is reinforced by the oxygen vacancy, contributes to the unprecedented cycle stability.
Constructing a solid electrolyte interface (SEI) is a highly effective approach to overcome the poor reversibility of lithium (Li) metal anodes. Herein, an adhesive and self‐healable supramolecular ...copolymer, comprising of pendant poly(ethylene oxide) (PEO) segments and ureido‐pyrimidinone (UPy) quadruple‐hydrogen‐bonding moieties, is developed as a protection layer of Li anode by a simple drop‐coating. The protection performance of in‐situ‐formed LiPEO–UPy SEI layer is significantly enhanced owing to the strong binding and improved stability arising from a spontaneous reaction between UPy groups and Li metal. An ultrathin (approximately 70 nm) LiPEO–UPy layer can contribute to stable and dendrite‐free cycling at a high areal capacity of 10 mAh cm−2 at 5 mA cm−2 for 1000 h. This coating together with the promising electrochemical performance offers a new strategy for the development of dendrite‐free metal anodes.
Stick with it: An adhesive and self‐healable supramolecular copolymer, comprising of pendant poly(ethylene oxide) segments and ureido‐pyrimidinone (Upy) hydrogen‐bonding moieties, has been developed and employed as a protection layer of a Li anode. This layer is self‐stabilizing because of a spontaneous reaction between the UPy groups and Li, enabling dendrite‐free cycling at a high areal capacity and current density.
X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive spectrometer (EDX) and X-ray photoelectron spectroscopy (XPS) are used to demonstrate that V2O5 is successfully ...coated on LiNiO2-based materials. The V2O5 layer will react with Li impurities on surface, which will reduce the pH value and rapid moisture uptake ability of LiNiO2-based materials. Cells tests indicate that V2O5-coating layer works as HF inhibitor and/or HF scavenger, which contributes a significant improvement in cycling performance and storage characteristics in electrolyte. In the mean time, V2O5 acts as isolating layer when cathode material contacts with electrolyte especially cycling at high voltage. Structural analysis shows that V2O5-coating layer has more advantage over other oxide coating in delaying Ni3+/Ni2+ transformation and lithium extraction from bulk surface, which benefits from the properties of V2O5 reacting with LiOH/Li2CO3 impurities on surface.
The effect of water washing on LiNi0.8Co0.1Mn0.1O2 cathode is extensively studied with respect to the electrochemical properties, structural stabilities, and storage characteristics. Water washing ...can improve the cycling performance and structural stability of LiNi0.8Co0.1Mn0.1O2 material in electrolyte, although with a slight deleterious effect on the capacity. Storage tests of the 4.3 V charged electrodes at 90 °C after 30 days show that Ni, Co, Mn in fresh and washed samples are dissolved in electrolyte, but the amount of dissolved Ni4+ ions after washing decreases by 31.5% compared with the fresh cathode. Moreover, the fresh sample transforms into the spinel phase with a Fd3m space group, whereas the washed sample remains as a layered hexagonal phase with an Rm3¯ space group. FTIR spectroscopy, transmission electron microscope (TEM), X-ray diffraction (XRD) and electrochemical studies indicate that the washed materials become more easily attached upon exposure to air, accompanied by significant increase in cationic disorder and NiO-like cubic phase near surface.
Water washing can improve the cycling performance and structural stability of LiNi0.8Co0.1Mn0.1O2 material in electrolyte, although with a slight deleterious effect on the capacity. Moreover, the fresh sample transformed into the spinel phase with a Fd3m space group, whereas the washed sample remained as a layered hexagonal phase with an R3¯m space group when storing in electrolyte at 90 °C for 7 days at charged state. However, the washed materials became more easily attached upon exposure to air, accompanied by significantly increased cationic disorder and NiO-like cubic phase near surface. Display omitted
► The effect of water washing on fresh LiNi0.8Co0.1Mn0.1O2 cathode was firstly studied. ► Water washing improved the cycling performance and structural stability of material. ► Water washing resulted in a slight deleterious effect on the capacity. ► Water washing made material much less resistant to H2O and CO2 when storing in air.
Rechargeable metal-air batteries and water splitting are highly competitive options for a sustainable energy future, but their commercialization is hindered by the absence of cost-effective, highly ...efficient and stable catalysts for the oxygen evolution reaction. Here we report the rational design and synthesis of a double perovskite PrBa
Sr
Co
Fe
O
nanofiber as a highly efficient and robust catalyst for the oxygen evolution reaction. Co-doping of strontium and iron into PrBaCo
O
is found to be very effective in enhancing intrinsic activity (normalized by the geometrical surface area, ∼4.7 times), as validated by electrochemical measurements and first-principles calculations. Further, the nanofiber morphology enhances its mass activity remarkably (by ∼20 times) as the diameter is reduced to ∼20 nm, attributed to the increased surface area and an unexpected intrinsic activity enhancement due possibly to a favourable e
electron filling associated with partial surface reduction, as unravelled from chemical titration and electron energy-loss spectroscopy.
Potassium-ion batteries (KIBs) are considered as a promising competitor to other metal-ion battery systems due to their low-cost and large-scale energy storage. However, their development is hindered ...by poor intercalation property of K ions in electrodes due to the heavier weight and larger size of K ion than those of Li ion. Therefore, achieving an ultra-long cycle life with high capacity and excellent rate capability remains a significant challenge for KIB electrodes. Herein, activated hollow carbon nanospheres (AHCSs), with enlarged interlayer spacing, oxygen-containing functional groups (OCFGs) on the surface and high specific surface area, are proposed as a new anode electrode for high-performance KIBs.
Ex situ
XRD and TEM results demonstrated that the enlarged interlayer spacing allow more reversible K ion intercalation into the carbon layer and readily accommodated large (de)potassiation strain without fracture, while OCFGs on AHCSs enhanced pseudocapacitance type behavior and specific capacity. Due to the synergistic effect of these structural features, the AHCSs served as anode for KIBs, exhibiting impressive electrochemical properties with high initial charge capacity of 370.2 mA h g
−1
at 0.2 A g
−1
, ultra-long cycling life for 5000 cycles at a high current density of 2.0 A g
−1
, as well as prominent rate capability of 137.0 mA h g
−1
at 4.0 A g
−1
. This study highlights the significant role of interlayer spacing, surface oxygen functionalization and hierarchical porosity of carbon-based anodes in potassium storage.
NH4F has been used to precipitate the lithium residue on surface of LiNi0.8Co0.1Mn0.1O2 and the in-situ precipitated LiF works as HF inhibitor during cycling, thus LiF-modified LiNi0.8Co0.1Mn0.1O2 ...exhibits noticeably enhanced rate capability and cycling performance compared with the pristine material. The capacity retention of LiF-modified LiNi0.8Co0.1Mn0.1O2 shows only 17.8% capacity loss after 200 cycles, while the pristine electrode suffers from 28.2% capacity loss and the improvement of cycling performance at 60°C is more significant. XRD, TEM, EDX and XPS are used to demonstrate that LiF is in-situ coated on LiNi0.8Co0.1Mn0.1O2. HF titration and EIS analysis were adapted to demonstrate the role of LiF prepared by this modified process.
NH4F has been used to precipitate the lithium residue on surface of LiNi0.8Co0.1Mn0.1O2 and the in-situ precipitated LiF works as HF inhibitor during cycling, thus the capacity retention of LiF-modified LiNi0.8Co0.1Mn0.1O2 shows only 17.8% capacity loss after 200 cycles, while the pristine electrode suffers from 28.2% capacity loss and the improvement of cycling performance at 60°C is more significant. HF titration and EIS analysis was adapted to demonstrate the role of LiF prepared by this modified process Display omitted .
•NH4F is used to precipitate the lithium residue on surface of LiNi0.8Co0.1Mn0.1O2.•LiF-modified LiNi0.8Co0.1Mn0.1O2 exhibits noticeably enhanced performance.•In-situ precipitated LiF works as HF inhibitor during cycling.
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