High-performance Lithium-ion Capacitors Research Articles

Lithium-Ion Capacitors: A Review of Strategies toward Enhancing the Performance of the Activated Carbon Cathode

Lithium-ion capacitors (LiC) are promising hybrid devices bridging the gap between batteries and supercapacitors by offering simultaneous high specific power and specific energy. However, an indispensable critical component in LiC is the capacitive cathode for high power. Activated carbon (AC) is typically the cathode material due to its low cost, abundant raw material for production, sustainability, easily tunable properties, and scalability. However, compared to conventional battery-type cathodes, the low capacity of AC remains a limiting factor for improving the specific energy of LiC to match the battery counterparts. This review discusses recent approaches for achieving high-performance LiC, focusing on the AC cathode. The strategies are discussed with respect to active material property modifications, electrodes, electrolytes, and cell design techniques which have improved the AC’s capacity/capacitance, operating potential window, and electrochemical stability. Potential strategies and pathways for improved performance of the AC are pinpointed.

Metal-organic frameworks (MOFs)-derived Mn2SnO4@C anode based on dual lithium storage mechanism for high-performance lithium-ion capacitors

Lithium-ion capacitors (LICs) are an emerging energy storage device that combines high energy density with high power density. Tin dioxide (SnO2) is considered a promising anode material due to its high theoretical capacity and low redox potential. However, severe volume expansion limits its practical application. In this study, a rhombic-shaped Mn2SnO4@C composite material with a uniform carbon coating was synthesized through pyrolysis of metal–organic frameworks (MOFs) and employed as an anode material for LIC. The material exhibited a dual lithium storage mechanism through alloying and conversion reactions. The Mn2SnO4@C anode exhibited excellent cycling stability due to the synergistic effect between Mn and Sn, and the uniform carbon coating. The anode maintained a capacity retention over 100 % at various current densities and a specific capacity reached 944 mAh g−1 after rate testing. Furthermore, a novel LIC was assembled using Mn2SnO4@C anode and coconut shell biomass carbon (CSBC) cathode, delivering an ultrahigh energy density of 217.9 Wh kg−1 at 210 W kg−1 and maintaining 25.1 Wh kg−1 even at a high power of 21 kW kg−1. This work applied alloy-conversion dual lithium storage mechanism anode materials to LICs, providing a new avenue for next-generation high-performance LICs.

Pseudocapacitive lithium-rich disordered rock salt vanadium oxide with 3D lithium-ion transport pathways for high-performance lithium-ion capacitor

Pseudocapacitive materials with high-rate behavior of lithium-ion charge storage offer a pathway to narrow the kinetics gap with capacitive porous carbon cathode toward lithium-ion capacitors both with high energy and high power densities. However, most of pseudocapacitive materials are subject to their relatively high redox potential, thus resulting in an undesirable decrease in energy density. Here, we demonstrate that lithium-rich disordered rock salt vanadium oxide (DRX-Li3V2O5), electrochemically transformed from V2O5 bulk, exhibits typical pseudocapacitive behaviors within a low working potential range between 0.1 and 2.0 V (vs. Li/Li+). The pseudocapacitive behaviors of DRX-Li3V2O5 mainly arise upon a percolating network that offers three-dimensional Li + transport pathways confirmed by Monte Carlo simulations. When the V2O5 bulk precursor is replaced by V2O5 nanosheets, as-obtained DRX-Li3V2O5 electrode displays a nearly symmetrical cyclic voltammetry curve, suggesting an ideal pseudocapacitive behavior. A lithium-ion capacitor further assembled by this pseudocapacitive DRX-Li3V2O5 anode, yields a cell voltage of 4.0 V, a maximum energy density of 186 Wh kg−1 and a maximum power density of 51,680 W kg−1 as well as long-term cycling life over 30,000 cycles, which are higher than or comparable to that of the state-of-art lithium-ion capacitors based on graphite and other pseudocapacitive materials.

Eco-friendly production of carbon electrode from biomass for high performance Lithium and Zinc ion capacitors with hybrid energy storage characteristics

Biomass derived carbon has emerged as promising electrode material for supercapacitors, owing to its low-cost, abundance and eco-friendly nature. Herein, we investigate the application of fluorine-enriched carbon derived from Ipomoea carnea as electrode in Zinc-Ion and Lithium-Ion capacitors (ZIC and LIC). The prepared IC is activated using KOH to enhance the surface properties and to create an amicable environment to accommodate metal ions. The properties of resultant biomass carbon (IC) are evaluated using various physical and chemical characterization techniques. The activated IC exhibited high surface area of 736.7 m2/g and suitable porous structure. The IC electrode is paired with Zn metal foil and an aqueous solution of ZnSO4/MnSO4 is used to fabricate ZIC. The device exhibits a capacitance of 168 F g−1 and retains about 79.5% of its initial capacitance after 5000 cycles. The prepared IC pre-lithiated and used to fabricate Li Ion capacitor, which delivered a capacitance of 155 F g−1 and retained 77.5% of initial capacitance after 5000 cycles. The implication biomass-derived carbon in LIC and ZIC is experimented in detail.

Interface engineering of CoSe2/N-doped graphene heterostructure with ultrafast pseudocapacitive kinetics for high-performance lithium-ion capacitors

Interface engineering of CoSe2/N-doped graphene heterostructure with ultrafast pseudocapacitive kinetics for high-performance lithium-ion capacitors

Fabricating tunable metal sulfides embedded with honeycomb-structured N-doped carbon matrices for high-performance lithium-ion capacitors

Fabricating tunable metal sulfides embedded with honeycomb-structured N-doped carbon matrices for high-performance lithium-ion capacitors

Novel high entropy oxide as anode for high performance lithium-ion capacitors

A fresh type of lithium-ion battery anode called high entropy oxide (HEO) has a remarkable specific capacity and outstanding cycle performance. The advantage of HEO consists in the distinct adjustable contents along with governable chemical constitution, which makes it possible to develop novel electrode materials using infinite combinations of elements. We successfully synthesized (FeCoNiCuZn)3O4 material via a straightforward hydrothermal way in this work. At a lofty current density of 1 A g−1, obtaining an invertible capacity of 540 mAh g−1 behind 500 cycles, the unique structure of (FeCoNiCuZn)3O4 exhibits remarkable stability. We analyzed the valence states of the metal elements and further investigated their relationship with electrochemical and kinetic properties after using X-ray photoelectron spectroscopy (XPS). Subsequently, by incorporating the (FeCoNiCuZn)3O4 anode with activated carbon (AC) in a lithium-ion hybrid capacitor (LIHC), which could deliver an outstanding power density of 4000 W kg−1 and energy density of 158 Wh kg−1 while maintaining excellent capacity retention property even after 5000 cycles, the anode showed considerable performance. This is the first time HEO has been used in LIHC, as far as we are aware.

Unleashing Anion Chemical Adsorption with Pore-Confined Single Atom Zinc for Enabling High-Performance Lithium-Ion Capacitors

Unleashing Anion Chemical Adsorption with Pore-Confined Single Atom Zinc for Enabling High-Performance Lithium-Ion Capacitors

High mass-loading N-rGO-T-Nb2O5/CuNW composite membrane for high-rate lithium-ion capacitor anodes

High-performance lithium-ion capacitors (LICs) show tremendous application prospects in new energy vehicles and portable electronic devices due to their excellent electrochemical properties. However, the low active mass loading and poor reaction rate of the current anode seriously limit the rate performance of LIC. Herein, we developed a high mass-loading N-doped reduced oxide graphene (N-rGO)-T-Nb2O5/Copper nanowire (CuNW) (GNC) composite membrane as an anode for high-rate LICs, which was obtained by compressing the corresponding 3D composite aerogel. Importantly, Li+ can be rapidly embedded/detached in large lattice spacing of T-Nb2O5 and high adsorption capacity of N-rGO, improving the rate performance of the GNC anode. Furthermore, the use of trace CuNWs conductive network instead of conventional Cu foil can effectively reduce the self-weight of the composite membrane for enhancing the specific capacity of the electrode. In lithium-ion half-cell, the high mass-loading GNC-2 (6.19 mg·cm−2 in coin cell) possessed high specific capacity, large rate performance, and excellent cycling life. The LIC consisted of prelithiated GNC-2 and N-rGO exhibited high energy density (173.9 Wh·kg−1), and power density (5242.8 W·kg−1) with outstanding cycle stability (capacitance retention rate of 93.2 % after 10,000 cycles at 3 A·g−1).

Interfacial/bulk synergetic effects accelerating charge transferring for advanced lithium-ion capacitors

The exploration of advanced materials through rational structure/phase design is the key to develop high-performance lithium-ion capacitors (LICs). However, high complexity of material preparation and difficulty in quantity production largely hinder the further development. Herein, Cu5FeS4-x/C (CFS@C) heterojunction with rich sulfur vacancies has successfully achieved from natural bornite, presenting low cost-effective and bulk-production prospect. Density functional theory (DFT) calculations indicate that rich vacancies in bulk phase can decrease band gap of bornite and thus improve its intrinsic electron conductivity, as well as the heterojunction spontaneously evokes a built-in electric field between its interfacial region, largely reducing the migration barrier from 1.27 eV to 0.75 eV. Benefited from these merits, the CFS@C electrodes deliver outperformed lithium storage performance, e.g., high reversible capacity (822.4 mAh/g at 0.1 A/g), excellent cycling stability (up to 820 cycles at 2 A/g and 540 cycles at 5 A/g with respective capacity retention of over or nearly 100%). With CFS@C as anode and porous carbon nanosheets (PCS) as cathode, the assembled CFS@C//PCS LIC full cells exhibit high energy/power density characteristics of 139.2 Wh/kg at 2500 W/kg. This work is expected to offer significant insights into structure modifications/devising toward natural minerals for advanced energy-storage systems.

Nitrogen-Doped Porous Carbon Derived from Coal for High-Performance Dual-Carbon Lithium-Ion Capacitors.

Lithium-ion capacitors (LICs) are emerging as one of the most advanced hybrid energy storage devices, however, their development is limited by the imbalance of the dynamics and capacity between the anode and cathode electrodes. Herein, anthracite was proposed as the raw material to prepare coal-based, nitrogen-doped porous carbon materials (CNPCs), together with being employed as a cathode and anode used for dual-carbon lithium-ion capacitors (DC-LICs). The prepared CNPCs exhibited a folded carbon nanosheet structure and the pores could be well regulated by changing the additional amount of g-C3N4, showing a high conductivity, abundant heteroatoms, and a large specific surface area. As expected, the optimized CNPCs (CTK-1.0) delivered a superior lithium storage capacity, which exhibited a high specific capacity of 750 mAh g-1 and maintained an excellent capacity retention rate of 97% after 800 cycles. Furthermore, DC-LICs (CTK-1.0//CTK-1.0) were assembled using the CTK-1.0 as both cathode and anode electrodes to match well in terms of internal kinetics and capacity simultaneously, which displayed a maximum energy density of 137.6 Wh kg-1 and a protracted lifetime of 3000 cycles. This work demonstrates the great potential of coal-based carbon materials for electrochemical energy storage devices and also provides a new way for the high value-added utilization of coal materials.

Construction of the hierarchical porous biochar with an ultrahigh specific surface area for application in high-performance lithium-ion capacitor cathode

Biochar with a highly accessible specific surface area can display a higher performance when it is used as the cathode of lithium-ion capacitors. Facing the complex composition and diversity of biomass precursors, there is a lack of a universally applicable method to construct hierarchical porous biochar controllably. In this work, a multi-stage activation strategy combining the feature of different activation methods is proposed for this target. To confirm the porous characteristic in prepared samples, N2 adsorption–desorption and transmission electron microscope were used. As the optimal sample, BC-P3K4S had the highest specific surface area of 3583.3 m2 g−1. Evaluated as the electrode for a lithium-ion capacitor, BC-P3K4S displayed a capacity of 139.1 mAh g−1 at 0.1 A g−1. After coupling it with pre-lithiated hard carbon, the full device exhibited a high energy density of 129.3 W h kg−1 at 153 W kg−1. The work outlined herein offers some insights into the preparation of hierarchical porous biochar from complex biomass by multistep activation method.Graphical

Binder-free boron-doped Si nanowires toward the enhancement of lithium-ion capacitor

Lithium-ion capacitors (LICs) are next-generation electrochemical storage devices that combine the benefits of both supercapacitors and lithium-ion batteries. Silicon materials have attracted attention for the development of high-performance LICs owing to their high theoretical capacity and low delithiation potential (∼0.5 V versus Li/Li+). However, sluggish ion diffusion has severely restricted the development of LICs. Herein, a binder-free anode of boron-doped silicon nanowires (B-doped SiNWs) on a copper substrate was reported as an anode for LICs. B-doping could significantly improve the conductivity of the SiNW anode, which could enhance electron/ion transfer in LICs. As expected, the B-doped SiNWs//Li half-cell delivered a higher initial discharge capacity of 454 mAh g−1 with excellent cycle stability (capacity retention of 96% after 100 cycles). Furthermore, the near-lithium reaction plateau of Si endows the LICs with a high voltage window (1.5–4.2 V), and the as-fabricated B-doped SiNWs//AC LIC possesses the maximum energy density value of 155.8 Wh kg−1 at a battery-inaccessible power density of 275 W kg−1. This study provides a new strategy for using Si-based composites to develop high-performance LIC.

Tailoring covalent triazine frameworks anode for superior Lithium-ion storage via thioether engineering

The development of high-performance lithium-ion capacitors (LICs) requires the use of electrode materials with higher energy/power density, faster charging, and longer cycle-life. Herein, by taking the merit of the strong designability of covalent triazine frameworks (CTFs), two tailor-made thioether-functionalized CTFs (S-CTF-Et and S-CTF-Me) with tunable properties are designed and synthesized as anodes for LICs. Due to the rich redox active sites and highly accessible specific surface area of the S-CTF-Et anode, which delivers a very large reversible capacity up to 1334 mAh g−1 at 0.1 A g−1, good rate capability (520 mAh g−1 at 2 A g−1) and cycling stability. After being comprehensively studied via ex-situ FT-IR, ex-situ XPS analyses, and theoretical calculations, it is found that the lithium-storage mechanism involves multi-electron redox reactions of benzene and triazine rings and coordination of thioether-groups by the accommodation of Li+. As proof of the new concept, an all CTF-related LIC device is assembled with S-CTF-Et anode and CTF-derived porous carbon (CTF-800) cathode for the first time, which delivers competitive energy and power densities (179.3 Wh kg−1 and 10.7 kW kg−1) and a capacity retention of 81 % after 10 000 cycles at a large current density of 2 A g−1.

Intertwined CNT Assemblies as an All-Around Current Collector for Volume-Efficient Lithium-Ion Hybrid Capacitors

The increasing demands for conversion systems for clean energy, wearable devices powered by energy storage systems, and electric vehicles have greatly promoted the development of innovative current collectors to replace conventional metal-based foils, including those in multidimensional forms. In this study, carbon nanotubes (CNTs) with desirable features and ease of processing are used in the preparation of floating catalyst-chemical vapor deposition-derived CNT sheets for potential use as all-around current collectors in two representative energy storage devices: batteries and electrochemical capacitors. Due to their short and multidirectional electron pathways and multimodal porous structures, CNT-based current collectors enhance ion transport kinetics and provide many ion adsorption and desorption sites, which are crucial for improving the performance of batteries and electrochemical capacitors, respectively. By assembling activated carbon-CNT cathodes and prelithiated graphite-CNT anodes, high-performance lithium-ion hybrid capacitors (LIHCs) are successfully demonstrated. Briefly, CNT-based LIHCs exhibit 170% larger volumetric capacities, 24% faster rate capabilities, and 21% enhanced cycling stabilities relative to LIHCs based on conventional metallic current collectors. Therefore, CNT-based current collectors are the most promising candidates for replacing currently used metallic materials and provide a valuable opportunity to possibly redefine the roles of current collectors.

Bamboo-derived flake-layer hierarchically porous carbon coupling nano-Si@porous carbon for advanced high-performance Li-ion capacitor

Lithium-ion capacitors (LICs) are increasingly being developed for energy storage as a consequence of their high power/energy density and ultra-long cycle lifetime. Herein, flake-layer hierarchically porous carbon (FPC) was obtained from bamboo liquid converted from bamboo powder using flake-layer Mg(OH)2 as template combined with KOH activation. Meanwhile, FPC-Si was obtained via loading nano-Si on the FPC surface through magnesiothermic reduction strategy. FPC has a high-specific surface area (SSA) of 1430.1 m2 g−1 and total pore volume of 2.84 cm3 g−1 with 90 % of mesopores. The high-SSA and mesopore volume contribute to superb capacitance and enhanced rate performance when used as the cathode in LIC. FPC-Si anode presents a rate capability of 720.5 mAh g−1 at 5 A g−1 with good cyclability. Therefore, the assembled LIC composed of FPC-Si anode and FPC cathode presents high energy/power density (179 Wh kg−1, 27.5 kW kg−1) and protracted lifetime of 8000 cycles (82.3 % capacitance retention). The current research indicates that the cathode requires not only high-SSA but also high mesopore volume. The mesopores as ions spreading highways can advance the ions transport and enhance the ions storage, causing high capacity and fine rate performance. The scalable methods offer a novel pathway for synthesizing biochar-based high-performance LICs.

Brewery waste derived activated carbon for high performance electrochemical capacitors and lithium-ion capacitors

In this study we report about the synthesis and characterization of an activated carbon (AC) displaying very large surface area (∼3600 m2 g−1) obtained from a cheap and abundant brewery waste product (Brewer's spent grains, BSG). AC based electrodes prepared from BSG demonstrated a very high specific capacitance (46 F g−1) and capacitance retention when evaluated in symmetric Electrical Double Layer Capacitors (EDLCs) devices with organic electrolytes. We showed that these electrodes can be successfully utilized for the realization of lab scale EDLCs and Lithium-ion Capacitors exhibiting very high energy and power densities as well excellent cycling stability (85% capacitance retention after 200 h of float test). Considering these results, the BSG-derived AC can be certainly considered as very promising material, which can contribute to the development of high performance, cost effective and eco-friendly high-power devices.

Carbon Nano-Onion-Encapsulated Ni Nanoparticles for High-Performance Lithium-Ion Capacitors

Lithium-ion capacitors (LICs) feature a high-power density, long-term cycling stability, and good energy storage performance, and so, LICs will be widely applied in new energy, new infrastructure, intelligent manufacturing. and other fields. To further enhance the comprehensive performance of LICs, the exploration of new material systems has become a focus of research. Carbon nano-onions (CNOs) are promising candidates in the field of energy storage due to the properties of their outstanding electrical conductivity, large external surface area, and nanoscopic dimensions. Herein, the structure, composition, and electrochemical properties of carbon nano-onion-encapsulated Ni nanoparticles (Ni@CNOs) have been characterized first in the present study. The initial discharge and charge capacities of Ni@CNOs as anodes (in half-cells (vs. Li)) were 869 and 481 mAh g−1 at 0.1 A g−1, respectively. Even at a current density of 10 A g−1, the reversible specific capacity remained at 111 mAh g−1. Ni@CNOs were used as anode materials to assemble LICs (full pouch cells (vs. activated carbon)), which exhibited compelling electrochemical performance and cycle stability after optimizing the mass ratio of the positive and negative electrodes. The energy density of the LICs reached 140.1 Wh kg−1 at 280.2 W kg−1 and even maintained 76.6 Wh kg−1 at 27.36 kW kg−1. The LICs also demonstrated excellent cycling stability with a 94.09% capacitance retention over 40,000 cycles. Thus, this work provides an effective solution for the ultra-rapid fabrication of Ni-cored carbon nano-onion materials to achieve high-performance LICs.

MnCO3 Cuboids from Spent LIBs: A New Age Displacement Anode to Build High-Performance Li-Ion Capacitors.

The advantage of hybridizing battery and supercapacitor electrodes has succeeded recently in designing hybrid charge storage systems such as lithium-ion capacitors (LICs) with the benefits of higher energy than supercapacitors and more power density than batteries. However, sluggish Li-ion diffusion of battery anode is one of the main barriers and hampers the development of high-performance LICs. Herein, is introduced a new conversion/displacement type anode, MnCO3 , via effectively recycling spent Li-ion batteries cathodes for LICs applications. The MnCO3 cuboids are regenerated from the spent LiMn2 O4 cathodes by organic acid lixiviation process, and hydrothermal treatment displays excellent reversibility of 535 mAhg-1 after 50 cycles with a Coulombic efficiency of >99%. Later, LIC is assembled with the regenerated MnCO3 cubes in pre-lithiated form (Mn0 +Li2 CO3 ) as anode and commercial activated carbon (AC) as the cathode, delivering a maximum energy density of 169.4Whkg-1 at 25°C with ultra-long durability of 15,000cycles. Even at various atmospheres like -5and 50°C, this LIC can offer a energy densities of 53.8and 119.5Whkg-1 , respectively. Remarkably, the constructed AC/Mn0 + Li2 CO3 -based LIC exhibits a good cycling performance for a continuous 1000cycles with >91% retention invariably for all temperature conditions.

Dual-functionally modified N/S doped hierarchical porous carbon and glycerol-engineered polyacrylonitrile carbon nanofibers combine for high-performance lithium-ion capacitors

Designing cathode and anode materials that can accommodate capacity and rate performance is a significant challenge in developing lithium-ion capacitors (LICs). Herein, we synthesize a unique N/S dual-doped hierarchical porous carbon (NSC) under the effect of pore distribution modification and heteroatom doping. The nanosheet shape and pore distribution of NSC are highly adjustable, while it demonstrates a reversible capacity that is tens of times more than that of unaltered pristine active carbon. Meanwhile, the prepared glycerol-engineered polyacrylonitrile nanofiber (GPN) form a fast conducting network in the presence of glycerol and carbon nanotubes (CNTs) and exhibit a 300% higher capacity compared to pure polyacrylonitrile nanofibers at 5 A g−1. On this premise, the constructed highly stable LIC (NSC//GPNx@CNTs) can achieve an energy density of 131.48 Wh kg−1 and have an excellent capacity retention rate (93.5%) over 10,000 cycles at a high current density (5 A g−1). This work may lead to new avenues for the preparation of heteroatom-doped porous carbon and redefine the electrode matching of highly stable LICs.