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The objective of this article is to illustrate the various fast charging techniques that are being used to charge the lithium-ion batteries in electric vehicles. Various charging protocols such as constant current, constant voltage, constant current constant voltage, multistage constant current, varying current method, pulse charging methods are critically reviewed and explained in their broader perspective of fundamental concepts to their modeling/simulation. Amongst, the constant current constant voltage charging approach is considered as a benchmark for other charging protocols in terms of the charging time, the charging efficiency, and battery life. A critical comparison among the various charging methods mentioned above are discussed and possible future research directions in the design and development of new fast charging techniques have been proposed based on the commercial and societal demands.

Nickel‐rich materials, as a front‐running cathode for lithium‐ion batteries suffer from inherent degradation issues such as inter/intragranular cracks and phase transition under the high‐current density condition. Although vigorous efforts have mitigated these current issues, the practical applications are not successfully achieved due to the material instability and complex synthesis process. Herein, a structurally stable, macrovoid‐containing, nickel‐rich material is developed using an affordable, scalable, and one‐pot coprecipitation method without using surfactants/etching agents/complex‐ion forming agents. The strategically developed macrovoid‐induced cathode via a self‐organization process exhibits excellent full‐cell rate capability, cycle life at discharge rate of 5 C, and structural stability even at the industrial electrode conditions, owing to the fast Li‐ion diffusion, the internal macrovoid acting as “buffer zones” for stress relief, and highly stable nanostructure around the void during cycling. This strategy for nickel‐rich cathodes can be viable for industries in the preparation of high‐performance lithium‐ion cells., A nickel‐rich cathode with a nanoparticle‐buffer layer induced macrovoid is developed via a one‐pot coprecipitation method without using surfactants/etching agents. The initial nanosized primary particles are dispersed toward the surface during the calcination process, which induces the nanoparticle‐based buffer zone and the structural stability. The prepared cathode material demonstrates a high specific capacity with strong structural integrity under the high C‐rate.

A comprehensive understanding of lithium-ion batteries became an essential aspect of solid-state electrochemical research due to their coalescence with routine. While it exhilarates us with increase in productivity of LIBs due to the emergence of Ni-rich cathode materials, the scope to upscale it according to the industrial needs is yet to be tapped to its full potential. Through this perspective article, the functional differences between LIBs and SIBs, state-of-the-art Single-crystalline NCM cathode, the status of the respective research works, crucial factors for industry scaling of the cathode materials, and the future scope of the research work are elucidated.

A peculiar architecture of one-dimensional MnO 2 nanowires was synthesized by an optimized hydrothermal route and has been lucratively exploited to fabricate highly efficient microporous electrode overlays for lithium batteries. These fabricated electrodes comprised of interconnected nanoscale units with wire-shaped profile which exhibits high aspect ratio in the order of 10 2 . Their outstanding intercalation/de-intercalation prerogatives have also been studied to fabricate lithium coin cells which revealed a significant specific capacity and power density of 251 mAh g −1 and 200 W kg −1 , respectively. A detailed electrochemical study was performed to elucidate how surface morphology and redox reaction behaviors underlying these electrodes influence the cyclic behavior of the electrode. Rate capability tests at different C-rates were performed to evaluate the capacity and cycling performance of these coin cells.

Sodium-ion batteries are the next-generation in battery technology; however, their commercial development is hampered by electrode performance. The P2-type Na2/3(Fe1/2Mn1/2)O2 with a hexagonal structure and P63/mmc space group is considered a candidate sodium-ion battery cathode material due to its high capacity (∼190 mAh·g–1) and energy density (∼520 mWh·g–1), which are comparable to those of the commercial LiFePO4 and LiMn2O4 lithium-ion battery cathodes, with previously unexplained poor cycling performance being the major barrier to its commercial application. We use operando synchrotron X-ray powder diffraction to understand the origins of the capacity fade of the Na2/3(Fe1/2Mn1/2)O2 material during cycling over the relatively wide 1.5–4.2 V (vs Na) window. We found a complex phase-evolution, involving transitions from P63/mmc (P2-type at the open-circuit voltage) to P63 (OP4-type when fully charged) to P63/mmc (P2-type at 3.4–2.0 V) to Cmcm (P2-type at 2.0–1.5 V) symmetry structures during the desodi...

Potency of the cathode material is an important feature for upgrading lithium-ion/sodium-ion battery technology for next-generation applications such as in electrical grids and advanced electric vehicles. Various limitations related to electrochemical and socio-economic issues of these batteries are current research challenges. Amongst the various possible solutions to address such issues, developing nanostructured cathode materials, such as one-dimensional nanostructures, by versatile and easily scaled-up processes could be one of the options. Consequently, in the present study, Li1+x(Mn1/3Ni1/3Fe1/3)O2 one-dimensional nanofibers have been fabricated via a simple and low-cost electrospinning technique and used as a cathode material in lithium-ion batteries, which showed an improved initial reversible capacity (∼109 mA h g−1) and cyclic stability at the 0.1 C rate when compared to the performance of Li1+x(Mn1/3Ni1/3Fe1/3)O2 nanoparticles. On the other hand, the feasibility of this low-cost and eco-friendly material was also tested in sodium-ion batteries, and the same trend is observed. The enhanced electrochemical and structural features in both systems could be ascribed to the exceptional features of one-dimensional nanofibers such as efficient electron transport, facile strain relaxation, and short Li+/Na+ diffusion pathways.

Cathode material degradation during cycling is one of the key obstacles to upgrading lithium-ion and beyond-lithium-ion batteries for high-energy and varied-temperature applications. Herein, we highlight recent progress in material surface-coating as the foremost solution to resist the surface phase-transitions and cracking in cathode particles in mono-valent (Li, Na, K) and multi-valent (Mg, Ca, Al) ion batteries under high-voltage and varied-temperature conditions. Importantly, we shed light on the future of materials surface-coating technology with possible research directions. In this regard, we provide our viewpoint on a novel hybrid surface-coating strategy, which has been successfully evaluated in LiCoO2 -based-Li-ion cells under adverse conditions with industrial specifications for customer-demanding applications. The proposed coating strategy includes a first surface-coating of the as-prepared cathode powders (by sol-gel) and then an ultra-thin ceramic-oxide coating on their electrodes (by atomic-layer deposition). What makes it appealing for industry applications is that such a coating strategy can effectively maintain the integrity of materials under electro-mechanical stress, at the cathode particle and electrode- levels. Furthermore, it leads to improved energy-density and voltage retention at 4.55 V and 45 °C with highly loaded electrodes (≈24 mg.cm-2 ). Finally, the development of this coating technology for beyond-lithium-ion batteries could be a major research challenge, but one that is viable.

The development of cathode materials with high capacity and cycle stability is essential to emerging electric-vehicle technologies, however, of serious environmental concern is that materials with these properties developed so far contain the toxic and expensive Co. We report here the Li-rich, Co-free Li1+xMO2 (M = Li, Ni, Mn, Fe) composite cathode material, prepared via a template-free, one-step wet-chemical method followed by conventional annealing in an oxygen atmosphere. The cathode has an unprecedented level of cation mixing, where the electrochemically-active component contains four elements at the transition-metal (3a) site and 20% Ni at the active Li site (3b). We find Ni(2+)/Ni(3+)/Ni(4+) to be the active redox-center of the cathode with lithiation/delithiation occurring via a solid-solution reaction where the lattice responds approximately linearly with cycling, differing to that observed for iso-structural commercial cathodes with a lower level of cation mixing. The composite cathode has ∼75% active material and delivers an initial discharge-capacity of ∼103 mA h g(-1) with a reasonable capacity retention of ∼84.4% after 100 cycles. Notably, the electrochemically-active component possesses a capacity of ∼139 mA h g(-1), approaching that of the commercialized LiCoO2 and Li(Ni1/3Mn1/3Co1/3)O2 materials. Importantly, our operando neutron powder-diffraction results suggest excellent structural stability of this active component, which exhibits ∼80% less change in its stacking-axis than for LiCoO2 with approximately the same capacity, a characteristic that may be exploited to enhance significantly the capacity retention of this and similar materials.

Sodium-ion batteries can be the best alternative to lithium-ion batteries, because of their similar electrochemistry, nontoxicity, and elemental abundance and the low cost of sodium. They still stand in need of better cathodes in terms of their structural and electrochemical aspects. Accordingly, the present study reports the first example of the preparation of Na2/3(Fe1/2Mn1/2)O2 hierarchical nanofibers by electrospinning. The nanofibers with aggregated nanocrystallites along the fiber direction have been characterized structurally and electrochemically, resulting in enhanced cyclability when compared to nanoparticles, with initial discharge capacity of ∼195 mAh g(-1). This is attributed to the good interconnection among the fibers, with well-guided charge transfers and better electrolyte contacts.

Battery industries and research groups are further investigating LiCoO2 to unravel the capacity at high-voltages (>4.3 vs Li). The research trends are towards the surface modification of the LiCoO2 and stabilize it structurally and chemically. In this report, the recent progress in the surface-coating materials i.e., single-element, binary, and ternary hybrid-materials etc. and their coating methods are illustrated. Further, the importance of evaluating the surface-coated LiCoO2 in the Li-ion full-cell is highlighted with our recent results. Mg,P-coated LiCoO2 full-cells exhibit excellent thermal stability, high-temperature cycle and room-temperature rate capabilities with high energy-density of ≈1.4 W h cc−1 at 10 C and 4.35 V. Besides, pouch-type full-cells with high-loading (18 mg cm−2) electrodes of layered-Li(Ni,Mn)O2 -coated LiCoO2 not only deliver prolonged cycle-life at room and elevated-temperatures but also high energy-density of ≈2 W h cc−1 after 100 cycles at 25 °C and 4.47 V (vs natural graphite). The post-mortem analyses and experimental results suggest enhanced electrochemical performances are attributed to the mechanistic behaviour of hybrid surface-coating layers that can mitigate undesirable side reactions and micro-crack formations on the surface of LiCoO2 at the adverse conditions. Hence, the surface-engineering of electrode materials could be a viable path to achieve the high-energy Li-ion cells for future applications.

The present study demonstrates a novel approach by which titanium foils coated with electropolymerized poly(3,4-ethylenedioxythiophene) (PEDOT) in combination with sputtered platinum can be processed into a high-surface area cathodes for dye-sensitized solar cells (DSSCs). A detailed study has been performed to elucidate how surface nanomorphology and I(-)/I(3-) redox reaction behaviors underlying these photocathodes impact the DSSC performances. From the analysis of the relevant electrochemical parameters, an intrinsic correlation between the photovoltaic performances and the cathode surface area has been deduced for such a system and explained on the basis of relative contributions of the galvanic coupling properties of the nanomorphology PEDOT film and platinum. Depending on the type of photocathodes incorporated, it was observed that these PEDOT coated cathodes can exhibit higher stability over a given time range and photo-conversion efficiencies 12-40%, higher than that achievable in absence of the intermediate PEDOT coatings. It has been shown that DSSCs based on such metal-polymer hybrid photo-cathodes allow significant room for improvement in the catalytic performance at the electrode/electrolyte interface.

The superior performance of lithium metal oxide cathode materials is a key aspect for the advanced development of lithium-ion battery (LIB) technology in portable electronics and high-end applications such as renewable energy units, electric vehicles (EVs) and hybrid electric vehicles (HEVs) etc. However, this battery technology suffers from some critical problems related to electrochemical performance, storage efficiency, safety and cost. Tremendous research is performed globally to solve these problems associated with battery performance. One of the potential ways to improve battery electrochemical performance and safety is by developing hybrid lithium metal oxide based one-dimensional (1D) nanostructures by simple and advanced electrospinning processes. These electrospun nanostructures of continuous fibrous morphology are attractive as new cathode materials due to their shorter Li ion diffusion pathways, high surface area and porous network. Since lithium-ion battery technology growth is tremendous and grabbing the attention of the world-wide scientific community, an update on recent progress in such fields is required. In this review, we discuss an in-depth summary about the significant role of electrospun lithium metal oxide based cathode materials in improving ionic conductivity, electrochemical stability, rate capability and safety; as well as possible future research challenges and prospects. In addition, we briefly describe the very recent progress of electrospun materials in anode and separator/electrolyte applications of LIBs.

The present study reports the electrospinning of TiO2-graphene composite nanofibers to develop conductive nano-fiber mats using polyvinylpyrrolidone as a carrier solution. This carrier solution was sublimated at 450 °C to attain a complete conducting continuous nanofibrous network. It was observed during the annealing that as the graphene content was increased to 1 wt% the continuous fiber morphology was lost. Annealing did not have any impact on the fiber diameter (∼150 nm) or morphology as the graphene content was maintained between 0.0–0.7 wt%. The surface porosity of these samples was found be in the range of 45–48%. The presence of graphene in TiO2 nanofibers was confirmed using Raman spectroscopy. Photoluminescence spectroscopy showed excitonic intensity to be lower in graphene-TiO2 samples indicating that the recombination of photo-induced electrons and holes in TiO2 can be effectively inhibited in the composite nanofibers. Fluorescence spectroscopy was used to confirm this phenomenon where blue and quenched emissions were observed for the electrospun TiO2 nanofibers and composite fibers, respectively. Conductivity measurements showed the mean specific conductance values obtained for TiO2-graphene composites to be about two times higher values than that of the electrospun TiO2 fibers. Assembling these TiO2-graphene fiber composites as photoanodes in dye sensitized solar cells, an efficiency of 7.6% was attained.