Stable Cycle Life Research Articles

Three-dimensional architecture of multichannel carbon fibers for enhanced lithium and sodium storage properties

Transition metal sulfides have garnered considerable attention in recent times as promising anode materials due to their high theoretical capacities for lithium and sodium storage. However, pristine metal sulfides suffer from poor rate and cycling stability. Herein, Se substituted NiS2 (denoted as NiSexS2-x) nanoparticles decorated multichannel carbon fibers (MCF/NiSexS2-x) were fabricated as anode materials for lithium and sodium-ion batteries. The distinct composition and unique architecture endow MCF/NiSexS2-x with enhanced reaction kinetics, improved electric conductivity, and superior structural stability. Consequently, the MCF/NiSexS2-x anode delivered a high capacity of >475 mAh g−1 at 1 A g−1 for Li storage with a highly stable cycle life of over 300 cycles. Moreover, when applied in sodium-ion batteries, MCF/NiSexS2-x achieved a superior capacity of >456 mAh g−1 at 0.2 A g−1 over 100 cycles with good rate retention.

PEDOT-intercalated NH4V3O8 nanobelts as high-performance cathode materials for potassium ion batteries

Potassium ion batteries (PIBs) have great potential to replace lithium ion batteries (LIBs) for large-scale energy storage applications because of the low cost and earth abundance of potassium resources. However, it is critically challenging to exploit an appropriate cathode material to accommodate the large size of K+. Herein, a conducting polymer (PEDOT) intercalation method is utilized to tailor the interlayer spacing of NH4V3O8 nanobelts from 7.8 Å to 10.8 Å, and afford rich oxygen vacancies inside the vanadate, thus enhancing its electronic conductivity and accelerating the K+ insertion/extraction kinetics. Benefiting from these features, PEDOT-intercalated NH4V3O8 (PNVO) nanobelts deliver an improved capacity of 87 mA h g−1 at 20 mA g−1, high rate capability of 51 mA h g−1 at 500 mA g−1, and a stable cycle life (capacity retention of 92.5 % after 100 cycles at 50 mA g−1). Even cycled at 200 mA g−1, PNVO nanobelts feature a long cycle life over 300 cycles with a capacity retention of 71.7 %. This work is of great significance for exploitation of PIBs cathode with improved electrochemical performance through pre-intercalation and defect engineering.

Unravelling structural changes of the Li1.2Mn0.54Ni0.13Co0.13O2 lattice upon cycling in lithium cell

Li-rich layered oxide materials (LRLOs) are the most promising positive electrodes materials for the next-generation Li-ion batteries. Nevertheless, cycle life stability and capacity retention are still inadequate and hinder their use in the commercial Li-ion devices. In fact, LRLOs undergo structural rearrangements and phase transitions upon cycling that reduce their electrochemical performances. Li1.2Mn0.54Ni0.13Co0.13O2 is one of the most studied LRLO materials, thanks to its high initial specific capacity, exceeding 300 mAh/g in the first cycle, that fades monotonically upon cycling. In this work, after a complete characterization of the pristine material, we demonstrate the electrochemical performances both in half and full cells and we shed new light on the structural degradations occurring upon cycling. By combining ex-situ synchrotron diffraction and Raman spectroscopy, we outline the structural evolution of the LRLO phase occurring in the first 10 cycles of lithium de-intercalation/intercalation, thus extending the understanding of the origin of capacity fading beyond the first cycle.

Integrated Design for Regulating the Interface of a Solid-State Lithium-Oxygen Battery with an Improved Electrochemical Performance.

A composite solid-state electrolyte (SSE) with acceptable safety and durability is considered as a potential candidate for high-performance lithium-oxygen (Li-O2) batteries. Herein, to address the safety issues and improve the electrochemical performance of Li-O2 batteries, a solvent-free composite SSE is prepared based on the thermal initiation of poly(ethylene glycol) diacrylate radical polymerization, and an integrated battery is achieved by injecting an electrolyte precursor between electrodes during the assembly process through a simple heat treatment. The Li-metal symmetric cells based on this composite SSE achieve a critical current density of 0.8 mA cm-2 and a stable cycle life of over 900 h at a current density of 0.2 mA cm-2. This composite SSE effectively inhibits the erosion of O2 on the Li metal anode, optimizes the interface between the electrolyte and cathode, and provides abundant reaction sites for the electrochemical reactions during cycling. The integrated solid-state Li-O2 battery prepared in this work achieves stable long cycling (118 cycles) at a current density of 500 mA g-1 at room temperature, showing the promising future application prospects.

Accommodation of Two-Dimensional SiOx in a Point-to-Plane Conductive Network Composed of Graphene and Nitrogen-Doped Carbon for Robust Lithium Storage.

Silicon oxides (SiOx) are one of the most promising anode materials for next-generation lithium-ion batteries owing to their abundant reserve and low lost and high reversible capacity. However, the practical application of SiOx is still hindered by their intrinsically low conductivity and huge volume change. In this regard, we design a novel anode material in which sheet-like SiOx nanosheets are encapsulated in a unique point-to-plane conductive network composed of graphene flakes and nitrogen-doped carbon spheres. This unique composite structure demonstrates high specific capacity (867.7 mAh g-1 at 0.1 A g-1), superior rate performance, and stable cycle life. The electrode delivers a superior reversible discharge capacity of 595.8 mAh g-1 after 200 cycles at 1.0 A g-1 and 287.5 mAh g-1 after 500 cycles at 5.0 A g-1. This work may shed light on the rational design of SiOx-based anode materials for next-generation high-performance lithium-ion batteries.

Electronic modulation and structural engineering of tetracyanoquinodimethane with enhanced reaction kinetics for aqueous NH4+ storage

Lithium-ion batteries (LIBs) have received much attention because of their environmental, financial, and safety concerns. The advantages of aqueous electrochemical energy storage include environmental friendliness and safety, and the development of prepared electrode materials is predicted to alleviate these issues. A redox-active organic compound, 7,7,8,8‑tetracyanoquinodimethane (TCNQ), is a suitable electrode for aqueous batteries. In this work, the porous and electronic interconnected structure of TCNQ is designed by electronic modulation and structure engineering. With the reduced graphene oxide (rGO) in situ homogeneous loading TCNQ by a one-step facile approach, the exquisite architecture has enhanced conductivity and connected conductive networks, favoring the storage and transportation of NH4+ or electrons in aqueous electrolytes. As a cathode, the obtained TCNQ-rGO exhibits superior performance for NH4+ batteries with an improved reversible capacity of 92.7 mAh/g at 1 A/g of quadruple capacity boosting to pure TCNQ and stable cycle life (5000 cycles at 10 A/g). The adjustment of the loading ratio of TCNQ and rGO for the cycling performance has been studied in detail. Furthermore, the superior ammonium storage mechanism of the TCNQ-rGO hybrid is thoroughly discussed by in situ Raman or ex situ measurements, which also determine the redox activity center groups of the TCNQ-rGO hybrid. Energy level calculations are conducted to help illustrate its potential as an electrode material. Our work demonstrates that electronic modulation and structural engineering of TCNQ can improve the electrochemical performance of molecular organic compound-based electrodes for aqueous rechargeable batteries in a simple and effective way.

Single Nickel Atom Catalysts Enable Fast Polysulfide Redox for Safe and Long-Cycle Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have attracted great interest due to their low cost, high theoretical energy density, and environmental friendliness. However, the sluggish conversion of lithium polysulfides (LiPS) to S and Li2 S during the charge/discharge process leads to unsatisfactory rate performance of lower to 0.1 C (1 C = 1675 mA g-1 ) especially for Li-S pouch batteries, thus hindering their practical applications in high power batteries. Here, well-defined and monodispersed Ni single-atom catalysts (SACs) embedded in highly porous nitrogen-doped graphitic carbons (NiSA-N-PGC) are designed and synthesized to form Ni-N4 catalytic sites at the atomic level. When serving as a bifunctional electrocatalyst, the Ni-N4 catalytic sites cannot only promote the interfacial conversion redox of LiPS by accelerating the transformation kinetics, but also suppress the undesirable shuttle effect by immobilizing LiPS. These findings are verified by both experimental results and DFT theoretical calculations. Furthermore, Li ions show low diffusion barrier on the surface of Ni-N4 sites, resulting in enhanced areal capacity of batteries. As a result, the Li-S battery delivers stable cycling life of more than 600 cycles with 0.069% capacity decay per cycle at a rate of 0.5 C. More importantly, the Li-S pouch cells with NiSA-N-PGC show an initial capacity of 1299 mAh g-1 at a rate of 0.2 C even with high sulfur loading of 6 mg cm-2 . This work opens up an avenue for developing single-atom catalysts to accelerate the kinetic conversion of LiPS for highly stable Li-S batteries.

A review on design considerations in polymer and polymer composite solid-state electrolytes for solid Li batteries

The current all-solid-state battery (ASSB) technology must stride through meticulous research work to reap the much-sought benefits of high energy density, stable cycling life and economical fabrication of ASSBs for large scale applications. Among all the prevailing scientific challenges, low room temperature ionic conductivity and interfacial impedance are the major roadblocks which need to be addressed before introducing them in large scale application in the high-power devices such as electric vehicles. Herein, we briefly discuss the background and the advances of polymeric and composite solid electrolyte systems with their fundamental ion transport mechanism, followed by a discussion on understanding the chemistry of various interfaces and interphases phenomena, various types of (in)stability issues, other bottleneck and challenging parameters, and the proposed solution to these in cell design strategies. In addition, this review also critically introspects the current measurement methods for collecting and reporting data on the ionic conductivity and reliability of the acquired data. The insights into these aspects will not only enlighten the readers about the recent trends in polymeric solid electrolytes but also will assist determining the correct type of measurement methods and the right cell design strategies.

Micro-nano Na3V2(PO4)3/C derived from metal-organic frameworks for high performance sodium ion batteries

Na3V2(PO4)3 has been widely studied due to its stable three-dimensional transmission channel structure as a cathode electrode of sodium ion batteries, but its micro particle size and low intrinsic electronic conductivity limit its further development. Therefore, hierarchical porous micro-nano NVP/C materials were successfully prepared using a metal-organic frameworks (MOFs) precursor. Because of the unique hierarchical porous micro-nano structure, 3D highly conductive network between surface and particles, and high specific surface area, M-NVP/C exhibits outstanding rate capability (95.0 mAh g−1 at a current density of 10 C) and extraordinary stable cycle life (the capacity decays from 111.2 mAh g−1 to 108.8 mAh g−1 after 500 cycles at 1 C, with a capacity retention rate of 97.8 %). This method provides a promising pathway for the application of MOFs in battery materials and promotes the development of SIBs in large-scale energy storage systems.

Next Generation Batteries: Status and Challenges of High Energy Rechargeable Lithium Batteries

Batteries play a critical role in modern society. The electrification of transportation and deep decarbonization of the energy infrastructure require the development and deployment of high energy, low-cost battery materials and technologies. Among the many different battery chemistries investigated, rechargeable batteries using lithium metal anode remain as one of the most feasible approaches for next generation high-performance and low-cost batteries. Here we will discuss and summarize the progresses and status of the research supported by the Battery500 Consortium. The consortium addresses both fundamental level materials and mechanistic problems and cell level integration and manufacturing challenges. The scope includes developing new electrolytes to reduce the side reactions and improve lithium metal deposition/stripping efficiency, improving cathode cycling stability and cathode utilization, understanding and controlling solid electrolyte interfacial reactions, cell design, optimization and validation. The consortium has made significant progress towards high energy cells (>350 Wh kg-1) and stable cycling life (>600 cycles). The research from the consortium also sheds new lights on the degradation and failure mechanisms of high energy lithium cells and the associated the interfacial reactions.

Hydrogen Stabilization and Activation of Dry-Quenched Coke for High-Rate-Performance Lithium-Ion Batteries.

Lithium-ion batteries (LIBs) have rapidly come to dominate the market owing to their high power and energy densities. However, several factors have considerably limited their widespread commercial application, including high cost, poor high-rate performance, and complex synthetic conditions. Herein, we use earth-abundant and low-cost dry-quenched coke (DQC) to prepare low-crystalline carbon as anode material for LIBs and tailor the carbon skeleton via a facile green and sustainable hydrogen treatment. In particular, DQC is initially pyrolyzed at 1000 °C, followed by hydrogen treatment at 600 °C to obtain C−1000 H2−600. The resultant C−1000 H2−600 possesses abundant active defect sites and oxygen functional groups, endowing it with high-rate capabilities (C−1000 H2−600 vs. commercial graphite: 223.98 vs. 198.5 mAh g−1 at 1 A g−1 with a capacity retention of about 72.79% vs. 58.05%, 196.97 vs. 109.1 mAh g−1 at 2 A g−1 for 64.01% vs. 31.91%), and a stable cycling life (205.5 mAh g−1 for 1000 cycles at 2 A g−1) for LIBs. This proves that as a simple moderator, hydrogen effectively tailors the microstructure and surface-active sites of carbon materials and transforms low-cost DQC into high-value advanced carbon anodes by a green and sustainable route to improve the lithium storage performance.

Composite TiO2/GeO2 for Higher Performance Inverse Opal Lithium-Ion Battery Electrodes

With the ever-growing technology industry and the need for more sustainable energy, the race to develop better, more efficient, renewable materials for lithium ion batteries is at the forefront of research. Metal oxide materials for use as electrodes in lithium batteries have been promising in recent years, transition metal oxides are favourable due to their low cost and nanostructured metal oxides exhibit encouraging electrochemical properties.1-2 Photonic crystal structures, more specifically inverse opal (IO) structures, are porous, highly interconnected structures which have proven to have advantageous benefits such as increased surface area and lower ion diffusion distances.3 In this work we combine TiO2 and GeO2 in solution phase in two ratios, 2:1 and 5:1 in favour of TiO2. Titanium oxides have high working potentials, higher than graphite which is most commonly used today. TiO2 has previously shown excellent long life cyclability and has shown little structural strain during the lithiation/delithiation process.4 Germanium has a high theoretical capacity of 1384 mAh/g and high electrical conductivity however it is expensive for use as an anode.5 Previous reports have shown that by nano-structuring GeO2 into an inverse opal structure, it can behave like pure germanium during cycling beyond the initial reduction and lithitation cycles.6 By combining both materials, we were able to achieve high capacity values for both ratios, 3 times the capacity of titanium IOs on their own. Work is ongoing to investigate the optimal cost to benefit ratio of the TiO2/GeO2 composites. Initial capacity results showcase high capacity retention and voltage stability. Reddy, M. V.; Subba Rao, G. V.; Chowdari, B. V. R., Metal Oxides and Oxysalts as Anode Materials for Li Ion Batteries. Chemical Reviews 2013, 113 (7), 5364-5457.Wu, H. B.; Chen, J. S.; Hng, H. H.; Wen Lou, X., Nanostructured metal oxide-based materials as advanced anodes for lithium-ion batteries. Nanoscale 2012, 4 (8), 2526-2542.Armstrong, E.; O'Dwyer, C., Artificial opal photonic crystals and inverse opal structures – fundamentals and applications from optics to energy storage. Journal of Materials Chemistry C 2015, 3 (24), 6109-6143.McNulty, D.; Carroll, E.; O'Dwyer, C., Rutile TiO2 Inverse Opal Anodes for Li-Ion Batteries with Long Cycle Life, High-Rate Capability, and High Structural Stability. Advanced Energy Materials 2017, 7 (12), 1602291.Zhang, Q.; Chen, H.; Luo, L.; Zhao, B.; Luo, H.; Han, X.; Wang, J.; Wang, C.; Yang, Y.; Zhu, T.; Liu, M., Harnessing the concurrent reaction dynamics in active Si and Ge to achieve high performance lithium-ion batteries. Energy & Environmental Science 2018, 11 (3), 669-681.McNulty, D.; Geaney, H.; Buckley, D.; O'Dwyer, C., High capacity binder-free nanocrystalline GeO2 inverse opal anodes for Li-ion batteries with long cycle life and stable cell voltage. Nano Energy 2018, 43, 11-21. Figure 1. (a) SEM image of a TiO2/GeO2 inverse opal (b) SEM image of TiO2/GeO2 IOs with EDX mapping overlay indicating position of titanium (green) and germanium (red). (c) and (d) Charge discharge profiles at 150 mA/g for the first 100 cycles for the 2:1 ratio and 5:1 ratio respectively.(e) Rate capability test for both ratios with specific currents ranging from 75 mA/g-450 mA/g. Figure 1

PEO-based Interlayers for LAGP-type Solid-State Lithium-Metal Batteries

Solid-state electrolytes (SSEs) are expected to play a decisive role for the realization of safer rechargeable batteries and may, additionally, allow for the employment of lithium-metal anodes, thus, paving the way for significantly higher energy densities. 1, 2 There are essentially two main groups of SSEs: (i) polymer and (ii) inorganic solids. The latter can be divided, e.g., into sulfide and oxide based electrolytes. 3 Among the oxides, the so-called NASICON-type electrolytes such as LAGP (lithium aluminum germanium phosphate) are considered as attractive low-cost alternative compared to sulfides. 4 Nonetheless, the incompatibility of LAGP with lithium metal accompanied by the formation of highly resistive interfacial reaction products, detrimentally affecting cycle life and rate capability, remain a great challenge. 5 To overcome this issue, the introduction of polyether (e.g., polyethylene oxide, PEO) as protective interlayer between the lithium-metal anode and the LAGP SSE was proposed. 6, 7, 8 The successful use of such interlayers, however, requires a fast and efficient charge transfer across this interlayer. Herein, we present a comprehensive investigation of PEO-based interlayers comprising varying amounts of ionic liquid-based electrolytes, which consist ofN-butyl-N-methyl pyrrolidinium-based and lithium cations as well as bis(fluorosulfonyl)imide (FSI-) and bis(trifluoromethanesulfonyl)imide (TFSI-) anions. Optimized compositions and the incorporation of selected additives further enhances the charge transfer across this interlayer and the two interfaces with the LAGP electrolyte and lithium metal, enabling long-term stable cycle life and good rate capability of the resulting lithium-metal battery cells.

Construction of high-performance sulfurized poly(acrylonitrile) cathodes for lithium-sulfur batteries via catalytic and conductive regulation

Sulfurized poly(acrylonitrile) (SPAN) is an attractive cathode material for lithium-sulfur (Li-S) batteries with demonstrated stable cycling, reduced polysulfide shuttle, and low self-discharge rates. However, the sluggish reaction kinetics of SPAN cathodes greatly limit their capacity output and rate performance. Here, we report novel Se 0.03 SPAN/CNT-3 nanofibers as sulfur cathode materials, aiming to promote the redox kinetics of sulfur conversion by imparting both electronic conductivity and catalytic activity to SPAN. Specifically, selenium is uniformly distributed in the Se 0.03 SPAN/CNT-3 composite through Se–S bonds and facilitates the fast transport of Li-ions. While the CNTs embedded in nanofibers enable high electronic conductivity and provide extra contact between electrode and electrolyte, offering smooth transport channels for both electrons and ions. As a result, the Se 0.03 SPAN/CNT-3 cathode presents a high reversible capacity (791 mAh g −1 composite at 0.2 C), superior rate performance (638 mAh g −1 composite at 4 C), and extremely stable cycle life over 800 cycles. In particular, when tested in practical conditions of high areal loading (Se 0.03 S: 5.2 mg cm −2 ) and lean electrolyte (E/Se 0.03 S: 10 μL mg −1 ), this cathode delivers high reversible capacities of 733 mAh g −1 composite (0.1 C) and 672 mAh g −1 composite (0.2 C), demonstrating its great potential for future application. • A novel Se 0.03 SPAN/CNT-3 nanofibers material was prepared and studied as the cathode for Li-S batteries. • The electrode reaction kinetics was greatly enhanced by the catalytic and conductive regulation. • A remarkable active materials utilization of 94.8 % was achieved by the Se 0.03 SPAN/CNT-3 cathode at 0.2 C. • High reversible capacity and good cycle stability were maintained under high areal loading and lean electrolyte conditions.

Facile Electroless Plating Method to Fabricate a Nickel-Phosphorus-Modified Copper Current Collector for a Lean Lithium-Metal Anode.

The compatibility of current collectors with reactive Li is key to inducing stable Li cycling and prolonged cycle life of lean Li-metal batteries. Herein, a thin and uniform layer of Ni-P complex was built on the surface of a Cu current collector (NiP@Cu) via an efficient, controllable, and cost-effective electroless plating method. The thickness, morphology, composition, and roughness of the Ni-P deposition were successfully regulated. Lithiophilicity of the current collector was greatly improved by Ni-P deposition, which effectively reduced the Li nucleation overpotential and suppressed the Li dendrite growth. In addition, NiP@Cu promoted an inorganic LiF/Li3P-rich solid electrolyte interphase to facilitate interfacial charge transfer and eliminate excessive side reactions between Li and the electrolyte. As a result, the Coulombic efficiency of half-cells remained above 98.5% for more than 400 cycles at 0.5 mA/cm2 and 98.2% for more than 250 cycles at 1 mA/cm2. Full cells with NiP@Cu also showed superior performance compared to those with bare Cu. This work proposes a promising surface modification method to develop a stable, dendrite-free, and cost-effective anode current collector for high-energy-density lean Li-metal batteries.

Tailoring electronic-ionic local environment for solid-state Li-O2 battery by engineering crystal structure.

Solid-state Li-O2 batteries (SSLOBs) have attracted considerable attention because of their high energy density and superior safety. However, their sluggish kinetics have severely impeded their practical application. Despite efforts to design highly efficient catalysts, efficient oxygen reaction evolution at gas-solid interfaces and fast transport pathways in solid-state electrodes remain challenging. Here, we develop a dual electronic-ionic microenvironment to substantially enhance oxygen electrolysis in solid-state batteries. By designing a lithium-decorative catalyst with an engineering crystal structure, the coordinatively unsaturated sites and high concentration of defects alleviate the limitations of electronic-ionic transport in solid interfaces and create a balanced gas-solid microenvironment for solid-state oxygen electrolysis. This strategy facilitates oxygen reduction reaction, mediates the transport of reaction species, and promotes the decomposition of the discharge products, contributing to a high specific capacity with a stable cycling life. Our work provides previously unknown insight into structure-property relationships in solid-state electrolysis for SSLOBs.

V2O5 intercalated with polyaniline for improved kinetics in aqueous ammonium-ion batteries

The use of non-metal ammonium ions (NH 4 + ) as effective charge carriers in battery systems is receiving widespread attention because of their light weight and small hydration shells in water as well as abundancy of the elements. The research concerning NH 4 + ion redox chemistry in batteries is still in its infancy, mainly because the large ionic radius of NH 4 + would require a host material to have a wider open structure and thus limits the choice of electrode materials. NH 4 + ion redox chemistry is dominated by non-ionic chemical bonding such as hydrogen bonding with some covalent bonding in nature which plays a significant role in electrochemical performance of the battery. In this work, an in-situ intercalation technique is utilized to synthesize polyaniline-intercalated vanadium oxide with a nanoflower morphology for increased surface area and enhanced NH 4 + ion (de)intercalation kinetics. Through this strategy, an interlayer spacing of 13.99 Å between V-O layers is reached, offering large diffusion channels to accommodate NH 4 + ions which have an ionic radius of 1.48 Å and a hydrated radius of 3.31 Å. The diffusion kinetics of the NH 4 + ions, influenced by the hydrogen bonds formed between NH 4 + ion and O 2− in the host structure, are thus effectively enhanced by the unique π-conjugated structure of PANI, leading to high capacity, improved rate capability and improved cycle life. The as-prepared PANI-intercalated V 2 O 5 (PVO) demonstrates stable, ultrafast NH 4 + ion electrochemical storage based on hydrogen bond chemistry as elucidated by X-ray photoelectron spectroscopy and Raman spectroscopy characterizations. Additionally, the composition of the PVO electrode is optimized with respect to the amount of PANI between the V-O layers. The PVO with an optimal composition exhibits the best overall electrochemical performance, delivering a high capacity of 192.5 mA hg −1 and 39 mA hg −1 at specific currents of 1 and 20 A g −1 respectively, as well as a stable cycle life with a capacity retention of 98% at a specific current of 10 and 20 A g −1 . As such, the present work provides critical insights into the design of promising electrode materials for emerging aqueous non-metal batteries with intrinsic safety and reduced cost.

Bio-Waste Derived Honeycomb Structured Activated Carbons as Anode Materials for Lead-Carbon Hybrid Ultracapacitors

Lead-carbon hybrid ultracapacitors (Pb-C HUC) are the solution to the sulfation issue of lead-acid batteries. The Pb-C HUCs are of much interest due to the aqueous system with longer cycle life and higher power density. Here, honeycomb structured porous activated carbons with 1790 m2 g−1 of surface area were synthesized from Carica papaya biowaste by chemical treatment followed by carbonization at 800 °C (PAC-800). PAC-800 composite electrode delivers a specific capacitance of 250 F g−1 at 1 Ag−1 and has 10000 stable cycle life in 4.5 M H2SO4. Further, a kinetic study of the PAC-800 electrode illustrates that at 2 mV s−1, they show 61% of capacitive and 39% of pseudocapacitive charge storage. Pb-C HUCs fabricated using in situ activated PbO2 sheet as cathode and PAC-800 composite electrode as anode delivers 390 F g−1 at 1 A g−1 and have 93% capacitance retention over 15000 cycles at 5 A g−1. Further, the current Pb-C HUC results are compared with commercially available high surface area (2484 m2 g−1) carbons based Pb-C HUCs. This work illustrates an easy, scalable synthesis root for biowaste carbons and their electrochemical performance in Pb-C HUCs, which is on par with commercial high surface area carbons.

Spray-drying Al onto hydroxide precursors to prepare LiNi0.855Co0.095Al0.05O2 as a highly stable cathode for lithium-ion batteries

The very high specific discharge capacities of Ni> 90% cathodes are often undone by their extremely poor cycle life and thermal stability. Herein, Ni-poor, and Al-rich particle with double concentration gradients is fabricated by synthesizing particles of the Ni-rich hydroxide Ni0.9Co0.1(OH)2 in a highly efficient Taylor flow (TF) reactor and then depositing Al onto their surfaces using three methods: spray-drying and conventional wet and dry chemical coating. The uniformity of the surface distribution of Al on the Ni-rich transition metal oxide cathode materials affected the overall structural and electrochemical stability. Among our three systems, the cathode material prepared with the spray-dried Al exhibited the best performance, with an initial discharge capacity of 196.9 mA h g–1 and capacity retention of 93% after 100 cycles at a rate of 1 C. It also demonstrated superior electrochemical performance at higher C-rates. For example, at 10 C, it delivered an initial discharge capacity of 134.4 mA h g–1, compared with 56.8 mA h g–1 for the Al-free LiNi0.9Co0.1O2. We attribute this enhanced electrochemical performance to the presence of Al and its uniform distribution (through spray-drying processing) on the outer layer of the active material, with the Ni and Co elements remaining mainly within the core.

Polyanilines from spent battery powder and activated carbon: Electrodes for asymmetric supercapacitor cell

AbstractThis work aims to use the electro‐active materials for energy storage application from the waste raw material source, readily and indigenously available materials. Nowadays, the use of waste sources to prepare electro‐active materials for energy storage applications is trending due to their low‐cost, high availability, reduced environmental problems, and so forth. In this direction, Polyaniline (PANI) is prepared using a MnO2 oxidant collected from waste Zn‐C cells. PANI displayed a compact and interconnected granular morphology with a surface area (39 m2 g−1), pore volume (0.19 cm3 g−1), and pore diameter (2.2 nm). Activated carbon (AC) has a surface area (860 m2 g−1), pore volume (199 cm3 g−1), and pore diameter (1.2 nm) is purchased locally. FT‐IR, XRD, and EDAX spectra support the formation of polyaniline salt with a small amount of Mn and Zn. The asymmetric cell is constructed using a PANI as a positive electrode and carbon as negative electrode material. The cell (PANI//AC) shows a high specific capacitance of 157 F g−1 at a current density of 5 mA cm−2. The cell offers a cycle life stability of 5000 cycles with a coulombic efficiency of 93% at a current density of 10 mA cm−2.