Lithium-ion Capacitors Research Articles

Boosting the Capacity of Aqueous Li-Ion Capacitors via Pinpoint Surgery in Nanocoral-Like Covalent Organic Frameworks.

Aqueous lithium storage devices are promising candidates for next-generation energy storage applications, featuring low-cost, safety, environmental benignness, and grid-scale merits. Developing reliable anode materials with fast Li+ diffusion is paramount to stimulate their development. Herein, the electrochemical performance and mechanism of a redox-active β-ketoenamine-linked covalent organic framework (COF) (2,6-diaminoanthraquinone and 2,4,6-triformylphloroglucinol COF, DAAQ-TFP-COF) for lithium storage in aqueous electrolyte are explored for the first time. Systematic studies demonstrate that, by the conversion of neutral COF into anionic COF via a pinpoint surgery on the β-ketoenamine linkage, the resultative COF shows doubled Li+ storage capacity (132 mAh g-1 at 0.5 A g-1 , 87% of theoretical specific capacity), good rate capability (108 mAh g-1 at 10 A g-1 ), and excellent cyclability in 1000 cycles. This pinpoint surgery can be promising in extending the electrochemical applications of β-ketoenamine-linked COFs. The Li+ storage mechanism is investigated by ex situ electron paramagnetic resonance, in situ/ex situ Fourier transform infrared investigations, and density functional theory calculations. As a proof of new concept, a novel aqueous lithium-ion capacitor assembled with DAAQ-TFP-COF anode delivers high specific capacitance of 224 F g-1 (0.1 A g-1 ), supercapacitor-level power density (≈4000 W kg-1 ), and long cyclability.

Experimental and numerical analysis of holistic active and passive thermal management systems for electric vehicles: Fast charge and discharge applications

Lithium-ion capacitors (LiCs) are commonly used as power sources for electric vehicles (EVs) due to the combined advantages of electric double-layer capacitors (EDLCs) and lithium-ion batteries (LiBs) comprising high energy density, high power density, and long lifetime. However, the performance of the LiCs is susceptible to temperature. Therefore, a robust thermal management system (TMS) is crucial for EVs to operate efficiently and safely. In this work, holistic active and passive TMSs are designed to control the maximum temperature of the cell. In this regard, an air-cooled TMS (ACTMS) and a compact liquid-cooled TMS (LCTMS) are among the active cooling systems, where pure paraffin phase change material (PCM), PCM with added aluminum mesh grid foil (PCM-Al), PCM with an added heat sink (PCM-HS), and heat pipe cooling system (HPCS) are the investigated passive TMSs. Moreover, the experimental results are verified against numerical analysis using a computational fluid dynamics (CFD) software, COMSOL Multiphysics. The most efficient active and passive cooling systems are then selected in the CFD simulations to make a robust hybrid TMS for a module of LiC cells. The results exhibit that the LCTMS has the best performance where the maximum temperature of the cell is controlled at 32.5 °C, which shows the reduction of 41.2% compared to the natural convection (NC) case study. The PCM-HS has the best performance among the passive cooling systems, decreasing 38.3% compared to the NC. Moreover, the hybrid TMS decreases the maximum temperature by 50.1% while uniformizing the temperature along with the module by keeping the temperature difference below 4.5 °C between the coldest and hottest points on the cell.

Advanced Thermal Management Systems for High-Power Lithium-Ion Capacitors: A Comprehensive Review

The acceleration demand from the driver in electric vehicles (EVs) should be supported by high-power energy storage systems (ESSs). In order to satisfy the driver’s request, the employed ESS should have high power densities. On the other hand, high energy densities are required at the same time for EVs’ traction to minimize the range anxiety. In this context, a novel ESS has emerged that can provide high power and energy densities at the same time. Such technology is called lithium-ion capacitor (LiC), which employs Li-doped carbon as negative electrode and activated carbon as positive electrode. However, high heat generation in high current applications is an issue that should be managed to extend the LiCs life span. Hence, a proper thermal management system (TMS) is mandatory for such a hybrid technology. Since this ESS is novel, there are only several TMSs addressed for LiCs. In this review article, a literature study regarding the developed TMSs for LiCs is presented. Since LiCs use Li-doped carbon in their negative electrodes, lithium-titanate oxide (LTO) batteries are the most similar lithium-ion batteries (LiBs) to LiCs. Therefore, the proposed TMSs for lithium-ion batteries, especially LTO batteries, have been explained as well. The investigated TMSs are active, passive, and hybrid cooling methods The proposed TMSs have been classified in three different sections, including active methods, passive methods, and hybrid methods.

Nitrogen and phosphorous co-doped hierarchical meso—microporous carbon nanospheres with extraordinary lithium storage for high-performance lithium-ion capacitors

Lithium-ion capacitors (LICs), consisting of a battery-like negative electrode and a capacitive porous-carbon positive electrode, deliver more than twice the energy density of electric double-layer capacitors. However, their wide application suffers from low energy density and reduced cycle life at high rates. Herein, hierarchical meso—microporous carbon nanospheres with a highly disordered structure and nitrogen/phosphorous co-doped properties were synthesized through a facile template method. Such hierarchical porous structure facilitates rapid ion transport, and the highly disordered structure and high heteroatom content provide abundant active sites for Li+ charge storage. Electrochemical experiments demonstrated that the carbon nanosphere anode delivers large reversible capability, greatly improves rate capability and exhibits excellent cycle stability. An LIC fabricated with the carbon nanosphere anode and an activated carbon cathode yields a high energy density of 103 W h kg−1, an extremely high power density of 44,630 W kg−1, and long-term cyclability of over 10,000 cycles. This work presents how structural control of carbon materials at the nano/atomic scale can significantly enhance electrochemical performance, enabling new opportunities for the design of high-performance energy-storage devices.

A Mechanically Flexible Necklace-Like Architecture for Achieving Fast Charging and High Capacity in Advanced Lithium-Ion Capacitors.

Integration of fast charging, high capacity, and mechanical flexibility into one electrode is highly desired for portable energy-storage devices. However, a high charging rate is always accompanied by capacity decay and cycling instability. Here, a necklace-structured composite membrane consisting of micron-sized FeSe2 cubes uniformly threaded by carbon nanofibers (CNF) is reported. This unique electrode configuration can not only accommodate the volumetric expansion of FeSe2 during the lithiation/delithiation processes for structural robustness but also guarantee ultrafast kinetics for Li+ entry. At a high mass loading of 6.2mgcm-2 , the necklace-like FeSe2 @CNF electrode exhibits exceptional rate capability (80.7% capacity retention from 0.1 to 10Ag-1 ) and long-term cycling stability (no capacity decay after 1100 charge-discharge cycles at 2Ag-1 ). The flexible lithium-ion capacitor (LIC) fabricated by coupling a pre-lithiated FeSe2 @CNF anode with a porous carbon cathode delivers impressive volumetric energy//power densities (98.4WhL-1 at 157.1 W L-1 , and 58.9WhL-1 at 15714.3 WL-1 ). The top performance, long-term cycling stability, low self-discharge rate, and high mechanical flexibility make it among the best LICs ever reported.

Hierarchical MoS2/C@MXene composite as an anode for high-performance lithium-ion capacitors

The battery-type anodes and capacitor-type cathodes enable lithium-ion capacitors (LICs) to achieve high energy density and high power density concurrently. Nonetheless, the gap in capacity and electrochemical reaction dynamics between anodes and cathodes remains a grand challenge. In this work, we report the synthesis of hierarchical MoS2/C@MXene composite with uniform MoS2/C nanosheets grown on few MXene flakes by electrostatic flocculation and hydrothermal reaction. As a result, the restacking of MXene flakesis inhibitedeffectively by electrostatic flocculation, and the few-layer MXene provides abundant sites for the uniform growth of MoS2 nanosheets. Meanwhile, the amorphous carbon matrix derived from diethylenetriamine can further enhance the conductivity of MoS2 and mitigate the oxidation of MXene. Due to the desirable coupling effect between MoS2/C and MXene conductive networks, MoS2/C@MXene electrode demonstrates superior Li storage capacity. It delivers a reversible capacity of 600 mAh g−1 at 1.0 A g−1 after 700 cycles, along with excellent rate performance. Moreover, the assembled LIC device using MoS2/C@MXene as anode and three-dimensional porous carbon as cathode exhibits a high energy density of 164.5 Wh kg−1 at the power density of 225 W kg−1, and an energy density of 53.1 Wh kg−1 even at a high power density of 11.3 kW kg−1, as well as good cycling stability with capacity retention of 77.2% after 5000 cycles at 1.0 A g−1. These results indicate that MoS2/C@MXene might be promising anode materials for high-performance LICs.

High-energy graphite microcrystalline carbon for high-performance lithium-ion capacitor: Diffusion kinetics and lithium-storage mechanism

Graphite microcrystalline carbon (GMC) is a potential candidate for lithium storage devices because of its high degree of disorder in the crystalline structure. The mechanism that affects the energy-storage ability of GMC in its capacitive coupling state is still unclear. Herein, high-energy GMC is synthesized through a dual-activation approach, and its kinetics and lithium-storage mechanism to boost lithium-ion diffusion are further investigated. The porous graphite microcrystalline provides the structural advantage in raising the Li+ storage capability, promotes the rapid transfer of electrons/ions, and possesses high conductivity. The defective heterostructure stimulates the internal electric field effect, facilitating rapid charge convey and fast diffusion kinetics. The first-principles calculations reveal that the nitrogen vacancies generated in graphite crystallites provide abundant reactive sites and induce excessive electrons around the local nitrogen atoms to form negative charge centers for accelerating the conveyance of Li+. The GMC electrode displays a high capacity of 1195 mAh g−1 at 0.1 A g−1, while the assembled GMC//GMC lithium-ion capacitor device delivers a high energy density of 190.63 Wh kg−1 at 225 W kg−1. This work is expected to offer an in-depth mechanism of electrons/ions diffusion and lithium storage for high-energy carbon electrodes and provide rational ideas for the optimal construction of high-energy carbon-based materials.

A Comprehensive Review of Lithium-Ion Capacitor Technology: Theory, Development, Modeling, Thermal Management Systems, and Applications.

This review paper aims to provide the background and literature review of a hybrid energy storage system (ESS) called a lithium-ion capacitor (LiC). Since the LiC structure is formed based on the anode of lithium-ion batteries (LiB) and cathode of electric double-layer capacitors (EDLCs), a short overview of LiBs and EDLCs is presented following the motivation of hybrid ESSs. Then, the used materials in LiC technology are elaborated. Later, a discussion regarding the current knowledge and recent development related to electro-thermal and lifetime modeling for the LiCs is given. As the performance and lifetime of LiCs highly depends on the operating temperature, heat transfer modeling and heat generation mechanisms of the LiC technology have been introduced, and the published papers considering the thermal management of LiCs have been listed and discussed. In the last section, the applications of LiCs have been elaborated.

Choice of Binder on Conversion Type CuO Nanoparticles toward Building High Energy Li‐Ion Capacitors: An Approach Beyond Intercalation

AbstractIn this work, the assembly of lithium‐ion capacitor (LIC) is described by pairing conversion type CuO nanoparticles recovered from the Cu current collector of spent lithium‐ion batteries (r‐CuO) as battery type electrode and activated carbon (AC) as the capacitor type electrode. The Li‐storage property of r‐CuO is studied in the presence of two binders (polyvinylidene fluoride, PVDF and carboxymethylcellulose, CMC) and found the aptness of CMC in comparison with PVDF. Accordingly, the Li/r‐CuO half‐cells with CMC binder exhibits better electrochemical performance such that even after 150 charge–discharge cycles, the cells could retain a specific capacity of ≈680 mAh g−1 at a current density of 0.2 A g−1. The assembled LIC (AC/r‐Cu0+Li2O) having electrochemically pre‐lithiated r‐CuO phase with balanced mass loading of AC can exhibit a maximum energy density of 65.6 Wh kg−1 with excellent cyclic stability at 2 A g−1 for 10,000 cycles with ≈80% capacity retention. It is worth mentioning that the thus fabricated LIC shows decent performance at high (50 °C) and low (−5 and 10 °C) temperature conditions.

Hierarchical architecture of two-dimensional Ti3C2 nanosheets@Metal-Organic framework derivatives as anode for hybrid li-ion capacitors

Two-dimensional (2D) layered metal carbides materials called MXenes (e.g., Ti3C2) are significantly attentioned as electrode material for lithium-ion capacitors (LICs) because of its large surface-to-volume ratio and ultra-high electronic conductivity. Whereas, as anode electrode material, the performance and application prospects of Ti3C2 are severely restricted to its lower theoretical capacity. In this work, a straightforward and effective strategy to surmount the restrictions was developed to combine layered Ti3C2 nanosheets with dual Co/Zn metal–organic framework (MOF) polyhedrons derivatives through electrostatic assembly. Co3O4/ZnO polyhedrons could prevent the stacking of Ti3C2 nanosheets and provide prominent lithium storage capacity. Furthermore, the advanced structure of Ti3C2@Co3O4/ZnO as anode material could provide short Li+ paths, large electrolyte channels and excellent structural stability to enhance the electrochemical performance for LICs. As a result, the prepared Ti3C2@Co3O4/ZnO composite exhibited a specific capacity of 585.7 mAh/g at 0.1 A/g, and the electrode still delivered a capacity of 229 mAh/g at 2 A/g after 1000 cycles with 93% capacity retention in lithium-ion half cell. In addition, by assembling with activated carbon (AC) as cathode and Ti3C2@Co3O4/ZnO as anode, the LIC revealed an ultra-high energy density of 196.8 Wh/kg at a power density of 174.9 W/kg, and delivered a high energy output of 87.5 Wh/kg even at a power density of 3500 W/kg. And its capacitance retention reaches 75% after 6000 cycles at 2 A/g. The advanced structure, handy preparation, and outstanding performance of layered carbon-based material Ti3C2@hollow polyhedrons composite might provide promising applications in LICs.

Novel Hybrid Thermal Management System for High-Power Lithium-Ion Module for Electric Vehicles: Fast Charging Applications

Lithium-ion capacitors (LiC) are hybrid energy storage systems (ESS) combining the advantages of lithium-ion batteries and electric double-layer capacitors, including longer lifetime, high power, and energy densities. LiCs are popular for high-power applications where fast charge and discharge driving profiles are demanded from electric vehicles (EV). However, LiCs generate excess heat when they are exposed to fast charging/discharging profiles. Therefore, a robust thermal management system (TMS) is crucial, in order to ensure reliable operation. In this study, a novel hybrid TMS based on air-cooling system assisted phase change materials (PCM), heat pipes, and a heat sink is proposed for an LiC module under a 150 A continuous current profile. A very thin aluminum heat sink and flat copper heat pipes were added to the PCM to increase its thermal conductivity. An experimental test bench of the proposed TMS was developed, and the temperature distribution of the module for each of the individual LiC cells was studied. The maximum temperature of the module under natural convection, when there was not any cooling system, reached almost 59.8 °C. The experimental results showed that after using the proposed hybrid TMS, the hottest cell reached 36.18 °C while the coldest cell reached 35.54 °C. Therefore, 39.5% improvement could be seen during the whole charge and discharge process after 3000 s. Moreover, the temperature difference within the module, of four LiCs, was around 0.64 °C, which was exceptional.

Surface oxygen-deficient Ti2SC for enhanced lithium-ion uptake

Recently, MAX phases show great potential in lithium-ion uptake due to their excellent electrical conductivity and unique lamellar-structure accommodating lithium ions. However, the reports about MAX electrodes for lithium-ion battery up to now are relatively low. Herein we report the preparation of surface oxygen-deficient Ti2SC with abundant oxygen vacancies by a facile surface engineering method. When using as a lithium storage anode, this oxygen-deficient Ti2SC delivers a high capacity of 350 mAh/g at a current density of 400 mA/g as well as excellent rate performance, doubling the capacity compared to that of Ti2SC without oxygen vacancies. Confirmed by electrochemical impedance spectroscopy (EIS) and kinetic mechanism analyses, after reducing surface oxides and generation of oxygen vacancies, the as-received Ti2SC exhibits higher electrical conductivity and faster lithium ion diffusion. Thus this work offers a facial and effective strategy of optimizing the surface structure of MAX phases, further to achieve an enhanced lithium-ion uptake for lithium-ion batteries or capacitors.

2D Graphene/MnO Heterostructure with Strongly Stable Interface Enabling High‐Performance Flexible Solid‐State Lithium‐Ion Capacitors

AbstractThe delicate structural engineering is widely acknowledged as a powerful tool for boosting the electrochemical performance of conversion‐type anode materials for lithium storage. Here, a general electrostatic self‐assembly strategy is proposed for the in situ synthesis of MnO nano‐cabbages on negatively charged reduced graphene oxide (rGO/MnO). The strong interfacial heterostructure and robust lithium storage mechanism related to fast Li+ diffusion kinetics and high Li‐adsorption ability of rGO/MnO heterostructure are confirmed through operando experimental characterizations and theoretical calculation. Owing to the rapid charge transfer, enriched reaction sites, and stable heterostructure, the as‐synthesized rGO/MnO anode delivers a high capacity (860 mAh g−1 at 0.1 A g−1), superior rate capability (211 mAh g−1 at 10 A g−1), and cycle stability. Notably, the as‐assembled flexible pouch cell of activated carbon//rGO/MnO solid‐state lithium‐ion capacitors (LICs) possesses an exceptional energy density of 194 Wh kg−1 and power density of 40.7 kW kg−1, both of which are among the highest flexible solid‐state LICs reported so far. Further, the LICs possess an ultralong life span with ≈77.8% retention after 10 000 cycles and extraordinary safety, demonstrative of great potential for practical applications.

Pencil Scripted Ultrathin Graphene Nanostructure as Binder‐Free Battery‐Type Electrode for Li‐Ion Micro‐Capacitors with Excellent Performance

Herein, a binder‐free graphene nanostructure anode formulated by drawing on Cu current collector with a commercial 10B pencil is reported. The prepared pencil‐trace electrode (10B pencil graphite, 10B PG) shows an excellent cycling profile with ≈87% capacity retention characteristics after 1000 cycles. Further, a dual‐carbon lithium‐ion capacitor (LIC) is fabricated using the pencil‐trace electrode as battery‐type electrode and commercial activated carbon (AC) as capacitor electrode in aprotic organic solutions. The 10B PG is pre‐lithiated prior to LIC fabrication to ensure an ample supply of Li‐ions during cycling. The developed LIC, 10B PG/AC assembly, displays a remarkable energy density of 109.9 Wh kg−1 irrespective of the applied current density, that is, power.

Joint Component Sizing and Energy Management for Fuel Cell Hybrid Electric Trucks

This paper proposes a cost-effective way to design and operate fuel cell hybrid electric trucks (FCHETs) where a chance-constrained optimization is formulated. The aim of the introduced problem is to minimize a summation of component cost and operational cost with consideration of fuel cell (FC) degradation and cycle life of energy buffer. We propose to decompose the problem into two sub-problems that are solved by sequential convex programming. The delivered power satisfies a cumulative distribution function of the wheel power demand, while the truck can still traverse driving cycles with a similar speed and travel time without delivering unnecessarily high power. This allows to downsize powertrain components, including electric machine, FC and energy buffer. A case study considering different energy buffer technologies, including supercapacitor (SC), lithium-ion battery (LiB), and lithium-ion capacitor (LiC) is investigated in a set of trucking applications, i.e. urban delivery, regional delivery, construction, and long-haul. Results show that the power rating of the electric machine is drastically reduced when the delivered power is satisfied in a probabilistic sense. Moreover, the configuration with LiB as the energy buffer has the lowest expense but the truck with LiC can carry more payload.

MOF-derived molybdenum selenide on Ti3C2Tx with superior capacitive performance for lithium-ion capacitors

MOF-derived molybdenum selenide on Ti3C2Tx with superior capacitive performance for lithium-ion capacitors

Ultra-high rate and ultra-stable lithium storage enabled by pore and defect engineered carbon nanofibers

Carbon-based materials have emerged as promising anode candidates for lithium-ion capacitors (LICs) owing to the advantages of high electronic conductivity and environmental benignity. However, further development of carbonaceous anodes has been greatly hindered by the sluggish kinetics and insufficient cycling stability. Herein, mesopore-rich N-doped carbon nanofibers (MNCNF) membranes are designed as a free-standing anode material to achieve ultra-high rate and ultra-long lifespan Li storage performance. The interconnected network with rich mesopore volume, high doping level of pyridinic/pyrrolic N, and expanded interlayer spacing affords the as-fabricated MNCNF anode abundant active sites, promoted electronic conductivity and superior diffusion kinetics. With prominent merits of pore and defect engineering, MNCNF anode manifests extraordinary Li storage performance in terms of ultra-high rate capability (139 mA h g−1 at 50 A g−1) and ultra-long cycling stability (370 mA h g−1 after 10000 cycles at 10 A g−1). More importantly, LICs by using MNCNF as anodes deliver a high energy density of 165 Wh kg−1 and an ultra-high power density of 132 kW kg−1, together with a high capacitance retention of 84% after 20000 cycles. This study demonstrates the combination of pore and defect engineering for boosting Li storage performance and holds great promise for practical applications.

Na0.76V6O15@Boron Carbonitride Nanotube Composites as Cathodes for High-Performance Lithium-Ion Capacitors

Lithium-ion capacitors (LICs) are considered one of the most promising new-generation energy storage devices because they combine the advantages of lithium-ion batteries and supercapacitors. However, the widely used commercial carbon cathode greatly limits the electrochemical performance of existing LICs due to its limited specific capacity. Improving the specific capacity of the cathode is one of the keys to solving this problem. To this end, the Na0.76V6O15 (NaVO)@boron carbonitride nanotube (BCNNT) cathode has been successfully synthesized via a facile solid phase reaction and hydrothermal reaction followed by annealing. Benefitting from the synergy between the high conductivity of BCNNTs and the high capacity of NaVO, the NaVO@BCN cathode exhibits excellent capacity and good cyclic stability. A LIC was assembled by a prefabricated NaVO@BCN cathode and a prelithiated commercial hard carbon (HC) anode. Notably, the NaVO@BCN−1//HC LIC delivered an energy density of 238.7 Wh kg−1 at 200 W kg−1 and still delivered 81.9 Wh kg−1 even at 20 kW kg−1. Therefore, our strategy provides a novel idea for designing high-performance LICs.

Pre-lithiation optimized voltage ranges and MnO2/rGO negative electrodes with oxygen vacancies for enhanced performance of lithium-ion capacitors

Lithium-ion capacitors are identified as outstanding hybrid energy storage devices combining the advantages of lithium-ion batteries and supercapacitors. However, the kinetics mismatch between positive and negative electrodes blocks the electrochemical performance. Thus, we design moderate amount of oxygen vacancies in manganese oxide nanosheets/reduced graphene oxide composites (OV-MnO2/rGO) for lithium-ion capacitors. Oxygen vacancies in MnO2 crystal enhance lithium-ion diffusion and electric conductivity to offset kinetics mismatch. OV-MnO2/rGO in half cells delivers good specific capacity of 1052 mAh g − 1 at 0.1 A g − 1 and cyclic performance (87.3% capacity retention after 450 cycles). Asymmetric lithium-ion capacitors were assembled with OV-MnO2/rGO negative electrodes and N-doped carbon nanosheets positive electrodes. The real working voltage ranges of electrodes under different pre-lithiation degrees are further investigated in pouch cells with inbuilt lithium metal electrode. By optimizing voltage ranges of electrodes based on pre-lithiation, the devices yield ultrahigh energy density of 206.2 Wh kg −1 at 250 W kg −1, excellent power density of 25,000 W kg −1 at 41.7 Wh kg −1 and stable cycling performance (79.8% after 10,000 cycles).

Last developments in polymers for wearable energy storage devices

Last developments in polymers for wearable energy storage devices