Lithium-ion Capacitors Research Articles

CO2-derived nitrogen doped porous carbon as advanced anodes for lithium-ion capacitors

Porous carbon is considered one of the most promising anode materials for lithium-ion capacitors due to its high ionic and electronic conductivity, high lithium storage capacitance and high chemical stability. However, the green and low-carbon preparation is a great challenge for the current porous carbon, especially for heteroatoms doped porous carbon. Herein, we report a low-carbon and environmentally friendly method to prepare N-doped porous carbon by the novel reaction of greenhouse gas CO2 with 5LiH-LiNH2. N-doped porous carbon delivers a reversible lithium storage capacity of 904 mAh g−1 at 0.1 A g−1, When paired with commercial activated carbon, the as-assembled lithium-ion capacitors provide a high energy density of 112 Wh kg−1 at a power density of 198.6 W kg−1 with a capacitance retention of 72% at 1.0 A g−1 after 6000 cycles. This work provides a green and low-carbon strategy for converting greenhouse gas CO2 into N-doped porous carbon for high-performance lithium-ion capacitors.

Incorporating LLTO ceramic into PVDF/PEO polymer electrolyte for lithium-ion capacitor

Hybrid supercapacitors are a prominent energy storage option for electric vehicles because they have high power and energy densities. Electrolyte plays a major role in hybrid supercapacitor performance. Our report is on a ceramic composite polymer electrolyte made from poly (vinylidene fluoride) (PVDF)/poly (ethylene oxide) (PEO)/ Lithium Lanthanum titanate (LLTO), which we analyzed for its structure, thermal behavior, and electrical characteristics. The different weight percentages (10 wt%, 20 wt%, 30 wt% and 40 wt%) of LLTO were incorporated into the PVDF/PEO polymer blends to study the performance of the electrolyte by FTIR, microscopic analysis, TGA, and impedance spectroscopy. Based on the results, 40 wt% of LLTO containing CPE showed high liquid electrolyte uptake behaviour (275 %) and a high ionic conductivity value (3.94 mS/cm). In addition, incorporating LLTO affects the PVDF/PEO polymer backbone and enhances the amorphicity of polymer blends. This result enhances the polymer segmental motion and reduces the relaxation time. We fabricated hybrid supercapacitor coin cells using 10 wt% and 40 wt% of LLTO containing composite polymer electrolyte and tested them. The 40 wt% LLTO-containing CPE-based hybrid supercapacitor possesses a high specific capacitance value (182F/g) and a long cycle life (upto10000 cycles).

Balancing microcrystalline domains in hard carbon with robust kinetics for a 46.7 Wh kg−1 practical lithium-ion capacitor

As a promising electrochemical energy storage system, lithium-ion capacitors (LICs) exhibit alluring theoretical merits of high energy density, high power density and long cycle life. However, most of the LIC cells can hardly surpass the practical energy density threshold of 30 Wh kg−1, which greatly hinders their employments in various energy-oriented fields. Anthracite shows great prospect as low-cost and abundant carbon precursor to prepare anode material with plentiful Li-ion anchoring sites for high performance LICs. In this work, a scalable low-temperature hydrothermal disordering strategy is proposed to achieve balanced structural modification of anthracite into short-ranged turbostratic carbon precursor, which further transforms into microcrystalline hard carbon (MHC) with high electrical conductivity (13065 S m−1) and substantially improved energy storage kinetics. A practical large-capacity LIC pouch cell is fabricated using MHC anode and activated carbon cathode to deliver a maximum gravimetric and volumetric energy density of 46.7 Wh kg−1 and 66.8 Wh/L based on the total weight of cell, outperforming the commercially available LIC products from relevant enterprises. Moreover, the cell reveals an exceptional capacity retention of 94.7 % after 10,000 cycles at high current density. The work herein would emerge as a universal and feasible protocol to fabricate high-end carbon electrode for practical LICs in numerous energy-intensive occasions.

Precision pre-lithiated graphite anode for lithium-ion capacitors with exceptional high-temperature cycling stability

Abstract Pre-lithiation technology is essential for lithium-ion capacitors to have high voltage and cycle stability. In this work, we propose an in situ chemical pre-lithiation method, which can accurately control the depth of pre-lithiation in the graphite anode. After 1,000 charge/discharge cycles at a high temperature of 65 °C, the lithium-ion capacitor still has 85% discharge capacity. The anode using this pre-lithiation method was found to have a stable potential after cycling.

CoP Quantum Dots Embedded in Carbon Polyhedra through Co─P─C Bonding Enabling High‐Energy Lithium‐Ion Capacitors

AbstractPhosphides with high theoretical capacity are considered ideal anode materials for lithium‐ion capacitors (LICs), but poor electronic conductivity as well as unsatisfied cyclic stability limits the performance of the phosphides. Here a covalently bonded CoP@C heterostructure is reported, which consists of 5 nm CoP quantum dots (QDs) like pomegranate seeds pinned in carbon polyhedron through interfacial Co─P─C bonding. The ultrafine size of CoP QDs provides more reactive sites and a shorten electrons/ions diffusion path, boosting the specific capacity. The Co─P─C bond induces the energy band variation of CoP and increases the interfacial charge density, bringing about fast kinetics. Besides, the Co─P─C bond introduces a robust pining effect among CoP QDs and carbon polyhedra, greatly improving the structure stability of 5 nm CoP QDs. The CoP@C heterostructure electrode exhibits high capacity (nearly 1000 mAh g−1) and superior cycling stability. It is worth noting that a prototyped LIC full‐cell of YP80//CoP@C presents an impressive high energy density of 172 Wh kg−1 and a power density of 10.8 kW kg−1. Moreover, the LIC possesses an ultra‐long life, retaining 80% after 20,000 cycles. This study offers an effective design for phosphides achieving fast kinetics and superior structure stability through an interfacial bonding approach.

SnS2/GDYO as a high-performance negative electrode for lithium-ion capacitors

SnS2/GDYO as a high-performance negative electrode for lithium-ion capacitors

All-Covalent Organic Framework Nanofilms Assembled Lithium-Ion Capacitor to Solve the Imbalanced Charge Storage Kinetics

HighlightsAn all-covalent organic framework (COF) nanofilm-structured lithium-ion capacitor (LIC) was developed by custom-made COF nanofilms as the anode/cathode.The COF nanofilm-structured LIC exhibits good electrochemical properties via the fast Li+ transport kinetics of the anodic COFBTMB-TP nanofilm and the high specific capacity of the cathodic COFTAPB-BPY nanofilm.This work can realize the charge storage kinetics and capacity balance of anode/cathode in COFTAPB-BPY//COFBTMB-TP LIC.

One-dimensional Fe7S8 nanorods encapsulated in N, S co-doped carbon shells accelerate lithium storage kinetics for lithium-ion capacitors

Abstract The slow kinetics of battery-type anode materials for lithium-ion capacitors (LICs) hinder their matching with capacitive-type cathodes. Designing anode materials with greater capacity and improved rate performance is a key to solving this challenge. Here, we fabricated one-dimensional N, S co-doped carbon encapsulated Fe7S8 nanorods to realize fast lithium storage kinetics and stable cycling performance. The matched Fe7S8@C//AC LICs achieved an extraordinary energy density of 101 Wh kg−1 and a power density of 3927 W kg−1.

Metal–organic framework-derived CoSe2@N-doped carbon nanocubes for high-performance lithium-ion capacitors

Metal–organic framework-derived CoSe2@N-doped carbon nanocubes for high-performance lithium-ion capacitors

Edge-rich reduced microcrystalline graphite oxide for Li-ion hybrid capacitors with ultrahigh volumetric energy density

Compact and high-performance carbon cathode materials are vital to improve the gravimetric and volumetric energy/power density of advanced energy storage devices such as lithium-ion hybrid capacitors (LIHCs). Graphite has a high mass density and the areal specific capacitance at the edge plane is far larger than that in the basal plane. Hence, increasing the proportion of edges can effectively improve the specific capacitance of the carbon material. However, it is challenging to expose more edges of graphite due to its high thermal and chemical stability. In this work, a compact cathode is prepared through a facile high-temperature ammonia treatment of microcrystalline graphite oxide (MGO). The obtained edge-rich reduced microcrystalline graphite oxide (ER-RMGO) demonstrates abundant edge sites, a high mass density of 1.48 g cm−3 and an extremely high areal specific capacitance of up to 319.3 μF cm−2. As a result, the fabricated Li-ion hybrid capacitor delivers an ultrahigh volumetric energy density of 392 Wh L−1 and power density of 9.49 W LkW L−1. This work sheds light on the great potential of microcrystalline graphite derived edge-rich carbon materials for compact capacitive energy storage.

Fluorine-Free Lithium-Ion Capacitor with Enhanced Sustainability and Safety Based on Bio-Based ƴ-Valerolactone and Lithium Bis(Oxalato)Borate Electrolyte.

In this work, the properties of a novel electrolyte based on the combination of bio-based ƴ-valerolactone (GVL) solvent with lithium bis(oxalato)borate (LiBOB) salt and its use for lithium-ion capacitors (LICs) are presented. It is shown that the 1 m LiBOB in GVL electrolyte displays good transport properties, high thermal stability, and the ability to prevent anodic dissolution. Its impact on the performance of both battery-type and capacitive-type electrodes is evaluated. In this regard, special attention is paid to the filming properties associated with LiBOB and GVL decomposition at the electrode surfaces. To the best of the authors' knowledge, the full-cell devices assembled in this study are the first example of a fluorine-free LIC. These devices exhibit a favorable energy-to-power ratio, delivering 80Whkg-1 AM at 10000Wkg-1 AM along with excellent cycling stability, retaining 80% of the initial capacitance after 25000 cycles. Furthermore, post-mortem analysis of the LIC electrodes is conducted to gain deeper insights into the degradation mechanisms within the device.

MOF-derived porous graphitic carbon with optimized plateau capacity and rate capability for high performance lithium-ion capacitors

MOF-derived porous graphitic carbon with optimized plateau capacity and rate capability for high performance lithium-ion capacitors

Carbon-reinforced Ni3S2/Ti3C2Tx MXene composite as an anode for superior-performance lithium-ion capacitors

Lithium ion capacitors (LICs) are a new generation of energy storage devices that combine the super energy storage capability of lithium ion batteries with the satisfactory power density of supercapacitors. The development of high-performance LICs still faces great challenges due to the unbalanced reaction kinetics at the anode and cathode. Therefore, it is an inevitable need to enhance the electron/ion transfer capability of the anode materials. In this paper, to obtain a superior-rate and high-capacity Ni3S2-based anode, highly conductive Ti3C2Tx MXene sheets were introduced to sever as the carrier of Ni3S2 nanoparticles and simultaneously an amorphous carbon layer which coats onto the surface of Ni3S2 nanoparticles was in-situ generated by the carbonization of dopamine reactant. The as-synthesized Ni3S2/Ti3C2Tx/C composite exhibits a high specific surface area (112.6 m2/g) because of the addition of Ti3C2Tx that can reduce the aggregation of Ni3S2 nanoparticles and the in-situ generated amorphous carbon layer that can suppress the growth of Ni3S2 nanoparticles. The Ni3S2/Ti3C2Tx/C anode possesses a remarkable reversible discharge specific capacity (626.0 mAh/g under 0.2 A/g current density), which increases to 1150.8 mAh/g after 400-cycle charge/discharge measurement at the same measurement condition indicating eminent cyclability, along with superior rate capability. To construct a superior-performance LIC device, a sterculiae lychnophorae derived porous carbon (SLPC) cathode with an average discharge specific capacity of 73.4 mAh/g@0.1A/g was prepared. The Ni3S2/Ti3C2Tx/C//SLPC LIC device with optimal cathode/anode mass ratio has a satisfactory energy density ranging from 32.8 to 119.1 Wh kg−1 at the corresponding power density of 8799.4 to 157.5 W kg−1, together with a prominent capacity retention (95.5 %@1 A/g after 10,000 cycles).

Lithium-Ion Supercapacitors and Batteries for Off-Grid PV Applications: Lifetime and Sizing

The intermittent nature of power generation from photovoltaics (PV) requires reliable energy storage solutions. Using the storage system outdoors exposes it to variable temperatures, affecting both its storage capacity and lifespan. Utilizing and optimizing energy storage considering climatic variations and new storage technologies is still a research gap. Therefore, this paper presents a modified sizing algorithm based on the Golden Section Search method, aimed at optimizing the number of cells in an energy storage unit, with a specific focus on the unique conditions of Denmark. The considered energy storage solutions are Lithium-ion capacitors (LiCs) and Lithium-ion batteries (LiBs), which are tested under different temperatures and C-rates rates. The algorithm aims to maximize the number of autonomy cycles—defined as periods during which the system operates independently of the grid, marked by intervals between two consecutive 0% State of Charge (SoC) occurrences. Testing scenarios include dynamic temperature and dynamic load, constant temperature at 25 °C, and constant load, considering irradiation and temperature effects and cell capacity fading over a decade. A comparative analysis reveals that, on average, the LiC storage is sized at 70–80% of the LiB storage across various scenarios. Notably, under a constant-temperature scenario, the degradation rate accelerates, particularly for LiBs. By leveraging the modified Golden Section Search algorithm, this study provides an efficient approach to the sizing problem, optimizing the number of cells and thus offering a potential solution for energy storage in off-grid PV systems.

Preparation and Lithium-Ion Capacitance Performance of Nitrogen and Sulfur Co-Doped Carbon Nanosheets with Limited Space via the Vermiculite Template Method.

Nitrogen and sulfur co-doped graphene-like carbon nanosheets (CNSs) with a two-dimensional structure are prepared by using methylene blue as a carbon source and expanded vermiculite as a template. After static negative pressure adsorption, high-temperature calcination, and etching in a vacuum oven, they are embedded in the limited space of the vermiculite template. The addition of an appropriate number of mixed elements can improve the performance of a battery. Via scanning electron microscopy, it is found that the prepared nitrogen-sulfur-co-doped carbon nanosheets exhibit a thin yarn shape. The XPS results show that there are four elements of C, N, O, and S in the carbon materials (CNS-600, CNS-700, CNS-800, CNS-900) prepared at different temperatures, and the N atom content shows a gradually decreasing trend. It is mainly doped into a graphene-like network in four ways (graphite nitrogen, pyridine nitrogen, pyrrole nitrogen, and pyridine nitrogen oxide), while the S element shows an increasing trend, mainly in the form of thiophene S and sulfur, which is covalently linked to oxygen. The results show that CNS-700 has a discharge-specific capacity of 460 mAh/g at a current density of 0.1 A/g, and it can still maintain a specific capacity of 200 mAh/g at a current density of 2 A/g. The assembled lithium-ion capacitor has excellent energy density and power density, with a maximum power density of 20,000 W/kg.

Electrochemical conversion from hydroxyl to carbonyl groups for improved performance of dual-carbon lithium ion capacitors

Pseudocapacitance from oxygen functional groups of carbon materials have been taken advantage to improve the capacity of lithium ion capacitors (LICs). However, the Li+ adsorption of hydroxyl groups and the Li+ desorption from lithiated hydroxyl groups remain poorly understood. Herein, density functional theory (DFT) calculations in combination with experimental characterizations of hydroxyl-rich graphene (HRG) cathodes at different lithiated states are performed. The calculation results predict that fully lithiated hydroxyl groups undergo Li+ desorption at a high potential of 4.45 V (vs. Li+/Li), and consequent conversion into carbonyl groups instead of return to hydroxyl groups. Experimental investigations through galvanostatic charge/discharge tests and ex-situ X-ray photoelectron spectra (XPS) analyses of HRG verify the predicted Li+ desorption potential and the conversion. This electrochemical conversion is effective to obtain carbonyl-rich graphene (CRG) with significantly improved specific capacities. The conversion process can be completed in LIC full cells assembled with pre-lithiated HRG cathodes, through which an HRG//N-doped porous carbon (NPC) LIC transforms into a CRG//NPC LIC with improved performance. The dual-carbon CRG//NPC LIC delivers an energy density of 206.2 Wh kg−1 at a power density of 169.5 W kg−1, and superior cycling stability.

Enhanced Electrochemical Performance of Low-Content Graphene Oxide in Porous Co3O4 Microsheets for Dual Applications of Lithium-Ion Battery Anode and Lithium-Ion Capacitor

Enhanced Electrochemical Performance of Low-Content Graphene Oxide in Porous Co3O4 Microsheets for Dual Applications of Lithium-Ion Battery Anode and Lithium-Ion Capacitor

Disorder/order-heterophase VO2 for enhanced lithium storage performance in lithium-ion capacitors

Interfacial engineering has proved to be an effective strategy for improving the performance of electrode materials in many applications. Herein, we report the disorder-order engineering of VO2 nanorods, and construct a crystal core and a surface-amorphized shell heterostructure (denoted as A-VO2) by simple hydrothermal method and reduction reaction, as a promising anode of lithium ion capacitor (LIC). The tunable amorphous layer introduces a large number of oxygen vacancy, which can efficiently improve electronic conductivity and enhance Li ion storage capacity. The crystalline-amorphous heterointerface generated in A-VO2 can significantly reduce the surface energy of VO2 and Li+ diffusion barrier, as well as increase the charge storage sites. The crystalline-amorphous heterogeneous phases work synergistically to facilitate ion and electron transport and maintain structural stability in discharge/charge process. The A-VO2-2 nanorods electrode possesses high capacity of 309 mAh g−1 at 0.1 A g−1 after 300 cycles, obviously larger than the crystalline VO2 electrode. In addition, the LIC, assembled with A-VO2-2 nanorods as anode and commercial active carbon (AC) as cathode, exhibit great energy density of 76.75 and 22.05 W h kg−1 at power density of 195 and 9360 W kg−1. It can remain 38.9 % of the initial capacity after 5000 cycles, demonstrating an instructive paradigm for disorder-order engineering in LIC electrode materials.

Niobium boride (NbB2): Salt-templated synthesis, pseudocapacitive electrode and lithium-ion capacitor applications

Lithium-ion capacitors (LICs), which combine great power and energy density, have become promising energy storage and have been well studied recently. Developing novel battery-type anode materials is the key to mitigating the kinetic mismatch between the anode and cathode electrodes. In this paper, niobium diboride (NbB2) nanoparticles are synthesized via a salt-templated method and proposed for the first time as the anodes for LICs. NbB2 is a layered two-dimensional material similar to graphite, which is favorable to the intercalation and deintercalation of Li+. The NbB2 with high conductivity delivers outstanding long cycling stability (254.1 mAh g−1 after 800 cycles at 0.1 A g−1) and great rate capability. Moreover, a high-performance LIC is assembled employing the prepared NbB2 as anode and commercialized activated carbon (AC) as cathode, which can display an energy density of 68.76 Wh kg−1, a power density of 7.02 kW kg−1, and a capacity retention ratio of 98% after 10,000 cycles. The work presents the great potential of transition metal borides as electrode materials and accelerates the development of LICs.

In situ self-transformation strategy toward zinc selenide electrode for lithium-ion capacitors

Conversion/alloying mechanism anode materials, featuring its higher theoretical capacity, have been deemed to one of the most potential candidates in the context of lithium ion capacitors (LICs). Nevertheless, the Li+ diffusion sluggish kinetics and severe volume variations during repeatedly lithiation/delithiation process further impede their application. Herein, an in situ self-transformation strategy is proposed to unlock the cyclic stability of electrode material. Multiple characterization techniques are adopted to unfold the electrode storage mechanism, the evolution of crystal structure, as well as the kinetics after reconstruction. The hexagonal wurtzite (WZ) in rGO-coupled ZnSe would be transformed spontaneously to cubic zinc-blende (ZB) phases upon the first electrochemical cycling with Li+. Consequently, the WZ-ZnSe@rGO electrode delivers dramatically cycling stability (451 mAh g−1 after 220 cycles at 0.1 A g−1). Additionally, we also prepare cubic m-ZB-ZnSe@rGO through physical mixing method, exhibiting high Li-storage capacity (468 mAh g−1 at 0.1 A g−1). This work suggests that in situ self-transformation strategy is feasible for creating high-performance electrode materials.