A dual substitution strategy is introduced to Co-free layered material LiNi0.5Mn0.5O2 by partially replacing Li and Ni with Na and Al, respectively, to achieve a superior cathode material for lithium ...ion batteries. Na+ ion functions as a “pillar” and a “ cationic barrier” in the lithium layer while Al3+ ion plays an auxiliary role in stabilizing structure and lattice oxygen to improve the electrochemical performance and safety. The stability of lattice oxygen comes from the binding energy between the Ni and O, which is larger due to higher valences of Ni ions, along with a stronger Al–O bond in the crystal structure and the “cationic barrier” effect of Na+ ion at the high-charge. The more stable lattice oxygen reduces the cation disorder in cycling, and Na+ in the Li layer squeezes the pathway of the transition metal from the LiM2 (M = metal) layer to the Li layer, stabilizing the layered crystal structure by inhibiting the electrochemical-driven cation disorder. Moreover, the cathode with Na–Al dual-substitution displays a smaller volume change, yielding a more stable structure. This study unravels the influence of Na–Al dual-substitution on the discharge capacity, midpoint potential, and cyclic stability of Co-free layered cathode materials, which is crucial for the development of lithium ion batteries.
Cathode materials based on zLi2SiO3@LiNi0.6Co0.2Mn0.2O2 (z = 0, 0.03, 0.05, 0.08) (where “@” denotes “coated on the surface of”) have been successfully prepared via a syn-lithiation strategy. The ...cycling performance of LiNi0.6Co0.2Mn0.2O2 has been effectively enhanced by coating a Li2SiO3 thin film. Compared to the 81 mAh/g discharge capacity of the pristine materials, the 5 mol% Li2SiO3-coated LiNi0.6Co0.2Mn0.2O2 electrode exhibits 31% higher discharge capacity between 2.5 V and 4.5 V at a rate of 5 C. The reason for the improved cycling performance of LiNi0.6Co0.2Mn0.2O2 is Li2SiO3 coating and Si4+ doping, which stabilizes the structure, suppresses the direct contact between the active materials and electrolytes, enhances lithium ion diffusion at the electrode/electrolyte interface, and prevents the pulverization of active materials during repeated charging/discharging.
•Li2SiO3 was well coated LiNi0.6Co0.2Mn0.2O2, and Si4+ was doped into the structure.•Electrochemical performance had been improved by Li2SiO3 coating and Si4+ doping.•The mechanism of the Li2SiO3 coating and Si4+ doping was explored systematically.
In this study, self‐synthesized lithium trifluoro(perfluoro‐tert‐butyloxyl)borate (LiTFPFB) is combined with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to formulate a novel 1 m dual‐salt ...electrolyte, which contains lithium difluorophosphate (LiPO2F2) additive and dominant carbonate solvents with low melting point and high boiling point. The addition of LiPO2F2 into this novel dual‐salt electrolyte dramatically improves cycleability and rate capability of a LiNi0.5Mn0.3Co0.2O2/Li (NMC/Li) battery, ranging from −40 to 90 °C. The NMC/Li batteries adopt a Li–metal anode with low thickness of 100 µm (even 50 µm) and a moderately high cathode mass loading level of 10 mg cm−2. For the first time, this paper provides valuable perspectives for developing practical lithium–metal batteries over a wide temperature range.
The addition of lithium difluorophosphate (LiPO2F2) additive into a novel dual‐salt electrolyte dramatically improves cycleability and rate capability of a LiNi0.5Mn0.3Co0.2O2/Li (NMC/Li) battery, ranging from −40 to 90 °C. In this novel dual‐salt electrolyte, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and self‐synthesized lithium trifluoro(perfluoro‐tert‐butyloxyl)borate (LiTFPFB) are dissolved in dominant carbonate solvents with low melting point and high boiling point.
The composition of the solid electrolyte interphase (SEI) is crucial to stably operate solid‐state batteries based on lithium‐metal anodes. In this work, the redox state of the PVDF‐b‐PTFE (PVT) ...solid polymer electrolyte is regulated by introducing fully conjugated copper polyphthalocyanine metal (CuPcLi), improving the electron transfer kinetics to accelerate the decomposition of fluorinated ingredients. As a result, an effective SEI with enriched lithium fluoride forms in situ at the Li/electrolyte interface, which enhances the Li‐ion transport kinetics and regulates the lithium deposition behavior, delivering ultra‐stable lithium plating/stripping performance over 2000 h in the Li//Li half‐cell. In addition, the chemisorption between Cu2+ and O atoms from TFSI− restrains the movement of anions in the electrolyte, and the CuPcLi improves the lithium ion release, exhibiting a high lithium‐ion conductivity of 0.8 mS cm−1 and a high lithium‐ion transference number of 0.74. As a result, the solid polymer electrolyte of PVT‐10CuPcLi paired with LiFePO4 delivers fantastic cyclic performance with a capacity retention of 92% even after 1000 cycles at 1 C at room temperature. When paired with high‐voltage LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode, the cells can be operated at 1 C with superior capacity retention over 88% after 300 cycles.
Copper phthalocyanine with extended π‐conjugation improves electron transfer, enhancing the electrochemical redox dynamics of the electrolyte to achieve a LiF‐rich solid electrolyte interphase layer. The chemisorption between Cu2+ and O atoms from TFSI− restrains the movement of anions in the electrolyte, and the sulfonated copper polyphthalocyanine followed by lithiation process improves lithium ion release.
Despite their superior reduction stability to Li metal compared with conventional carbonate electrolytes, ethers have been precluded from use in high-voltage batteries due to their limited oxidation ...stability (<4 V). Herein, this issue can be effectively addressed by the synergistic effect strategy based on dual salt and fluoroethylene carbonate (FEC) as a co-solvent, which forms a unique Li + solvation structure with aggregated dual anions and induces more robust inorganic/organic composite fluorinated interphase layers. It is noted that this ether-based electrolyte presents an enlarged electrochemical window up to 4.6 V resulting from the enhanced oxidative stability by introducing FEC. Meanwhile, the interphase layers effectively improve the Li plating/stripping kinetics and interface stability. Besides, in situ FTIR, Raman spectra and theoretical calculations are used to confirm the solvation interactions. And the inorganic/organic composite fluorinated interphase layer component is verified by X-ray photoelectron spectroscopy (XPS) spectra. Using this ether-based electrolyte, the Li/Cu cells present colossal Li deposits with a high coulombic efficiency (≈98.95%). More significantly, the 4.4 V Li/LiCoO 2 battery exhibits excellent cycling stability with a capacity retention of 80% over 300 cycles. This work offers a promising approach to enable ether-based electrolytes for high-voltage Li metal batteries (LMBs).
Seed storage proteins (SSPs) are of great importance in plant science and agriculture, particularly in cereal crops, due to their nutritional value and their impact on food properties. During seed ...maturation, massive amounts of SSPs are synthesized and deposited either within protein bodies derived from the endoplasmic reticulum, or into specialized protein storage vacuoles (PSVs). The processing and trafficking of SSPs vary among plant species, tissues, and even developmental stages, as well as being influenced by SSP composition. The different trafficking routes, which affect the amount of SSPs that seeds accumulate and their composition and modifications, rely on a highly dynamic and functionally specialized endomembrane system. Although the general steps in SSP trafficking have been studied in various plants, including cereals, the detailed underlying molecular and regulatory mechanisms are still elusive. In this review, we discuss the main endomembrane routes involved in SSP trafficking to the PSV in Arabidopsis and other eudicots, and compare and contrast the SSP trafficking pathways in major cereal crops, particularly in rice and maize. In addition, we explore the challenges and strategies for analyzing the endomembrane system in cereal crops.
The voltage and capacity attenuation is one of the main bottlenecks limiting the commercialization of Li-rich layered materials, the introduction of a spinel structure and Li deficiencies into ...materials may mitigate or suppress these shortcoming. The Li-rich layered materials with surface layered/spinel heterostructures and Li deficiencies (LR-S) are prepared by a simple and ingenious manner; that is, the 10 wt % precursors are added to uptake the volatilize of Li ions, which produced from the Li-rich material (LR-0) in a high-temperature post-treatment process. The generation of the spinel structure and Li deficiencies in the LR-S sample are confirmed by the inductively coupled plasma mass spectrometry, X-ray diffraction, Raman spectra, and high-resolution transmission electron microscopy characterizations. The LR-S sample displayed excellent electrochemical performances; that is, the capacity retentions is 88.92% at 1 C after 200 cycles, and the voltage drop for each cycle is 1.91 mV, respectively. The reason is mainly attributed to the spinel structure serving as a pillar structure and the Li deficiencies modulating the oxidation products of the oxygen ion in the removal/uptake process.
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