Leon Shaw; Maziar Ashuri
Abstract
Layered lithium nickel manganese cobalt oxides, Li(NixMnyCoz)O2 where x + y + z = 1 (NMCs), have been studied extensively due to their higher capacity, less toxicity and lower cost compared to LiCoO2. However, widespread market penetration of NMCs as cathodes for Li-ion batteries (LIBs) is impeded by ...
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Layered lithium nickel manganese cobalt oxides, Li(NixMnyCoz)O2 where x + y + z = 1 (NMCs), have been studied extensively due to their higher capacity, less toxicity and lower cost compared to LiCoO2. However, widespread market penetration of NMCs as cathodes for Li-ion batteries (LIBs) is impeded by their poor capacity retention and low rate capability. Coatings provide an effective solution to these problems. This article focuses on review of the recent advancements in coatings of NMCs from the mechanism viewpoint. This is the first time that coatings on NMCs are reviewed based on their functionalities and mechanisms through which the electrochemical properties and performance of NMCs have been improved. To provide a comprehensive understanding of the functions and mechanisms offered by coatings, the following functions and mechanisms are reviewed individually: (i) scavenging HF in the electrolyte, (ii) scavenging water molecules in the electrolyte and thus suppressing HF propagation during charge/discharge cycles, (iii) serving as a buffer layer to minimize HF attack on NMCs and suppress side reactions between NMCs and the electrolyte, (iv) hindering phase transitions and impeding loss of lattice oxygen, (v) preventing microcracks in NMC particles to keep participation of most NMC material in lithiation/de-lithiation, and (vi) enhancing the rate capability of NMC cathodes. Finally, the personal perspectives on outlook are offered with an aim to stimulate further discussion and ideas on the rational design of coatings for durable and high-performance NMC cathodes for the next generation LIBs in the near future.
Satish Teotia; B.P. Singh; Anisha Chaudhary; Indu Elizabeth; Anchal Srivastava; Saroj Kumari; S. R. Dhakate; S. Gopukumar; R. B. Mathur
Abstract
The quick advancement of flexible energy storage gadgets has persuaded individuals to look for reliable electrodes with high mechanical flexibility and remarkable electrochemical performance. In the present study, we demonstrate a simple and scalable process to fabricate a flexible, light-weight, free-standing ...
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The quick advancement of flexible energy storage gadgets has persuaded individuals to look for reliable electrodes with high mechanical flexibility and remarkable electrochemical performance. In the present study, we demonstrate a simple and scalable process to fabricate a flexible, light-weight, free-standing polyvinylidene fluoride-multiwalled carbon nanotubes (PVDF-MWCNT) composite paper, which can be specifically utilized as a flexible anode for lithium ion batteries (LIBs). The excellent binding of MWCNT with PVDF matrix, developed by a straightforward vacuum filtration process, provides sufficient structural integrity to the composite paper. The breaking strength of the PVDF-MWCNT composite paper so formed is found to be 3.5 MPa with strain to failure of 11.25%. The composite paper so developed shows a good cycle reversible charge capacity when used as anode in a standard Li-ion battery. The PVDF-MWCNT composite paper provides a novel pathway to large scale fabrication of flexible electrodes which can be used without conducting support of copper sheet.
Eliana M. F. Vieira; Joao F. Ribeiro; Rui Sousa; Anabela G. Rolo; Manuela M. Silva; Luis M. Goncalves
Abstract
Design and fabrication of reliable materials with high capacity, cycling stability and good adhesion properties for flexible microbatteries remains a challenge. A 2 µm thick flexible solid-state Ge-LiCoO2 battery was fabricated and the structure, composition, thermal, optical, electrical, ...
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Design and fabrication of reliable materials with high capacity, cycling stability and good adhesion properties for flexible microbatteries remains a challenge. A 2 µm thick flexible solid-state Ge-LiCoO2 battery was fabricated and the structure, composition, thermal, optical, electrical, and electrochemical properties of the materials that determine and influence its electrochemical potential were investigated. RF-sputtered lithium cobalt oxide (LiCoO2) cathode and lithium phosphorus oxynitride (LiPON) electrolyte films were fabricated at 120 W and 100 W of power, respectively. A ~ 300 nm thick Ge anode was deposited by e-beam. The full-battery was fabricated using conventional and low-cost PVD processes. X-ray diffraction (XRD) and Raman spectroscopy confirms the hexagonal R͞3m phase of annealed LiCoO2. Differential scanning calorimetry (DSC) technique was applied to investigate the thermal behaviour of the LiPON film with a moderate electrical resistivity of 10 8 Ωcm and high optical transmission (> 75%) in the UV-Visible range. Bending experiments were also performed to evaluate thin-films adhesion and stability. Scanning electron microscopy (SEM) technique was used to evaluate the morphology of films surface and the layered structure of the full-battery. This detailed experimental study allows us to understand the discharge behavior of the fabricated Li-ion battery.
Tirupathi Rao Penki; Brij Kishore;N. Munichandraiah; D. Shanmughasundaram
Abstract
Carbon has been prepared by pyrolysis of grated, milk-extracted coconut kernel at 600 ºC under nitrogen atmosphere. The disordered carbon has sheet like morphology. The carbon exhibits a high reversible Li + intercalation capacity in a non-aqueous electrolyte. The initial charge and discharge capacities ...
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Carbon has been prepared by pyrolysis of grated, milk-extracted coconut kernel at 600 ºC under nitrogen atmosphere. The disordered carbon has sheet like morphology. The carbon exhibits a high reversible Li + intercalation capacity in a non-aqueous electrolyte. The initial charge and discharge capacities are 990 and 400 mAh g -1 , thus resulting in an irreversible capacity loss of 590 mAh g -1 . Nevertheless, subsequent discharge capacity is stable over a large number of charge-discharge cycles. The electrodes withstand charge-discharge currents as high as 1257 mA g -1 and they deliver discharge capacity of 80 mAh g -1 . Diffusion coefficient of Li+ obtained from galvanostatic intermittent titration is 6.7 x 10 -12 cm 2 s -1 . Thus the coconut kernel derived carbon is a suitable anode material for Li-ion batteries.
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