Cathode Loading Research Articles

Rational Design of a Cost-Effective Biomass Carbon Framework for High-Performance Lithium Sulfur Batteries

Lithium–sulfur (Li-S) batteries are the most attractive candidates for next-generation large-scale energy storage because of their high theoretical energy density and the affordability of sulfur. However, most of the reported research primarily concentrates on low sulfur loading (below 2 mgs cm−2) cathodes using binders and traditional collectors, thus undermining the expected energy density. Herein, a N, O co-doped carbon nanotube (N, O-CNT) decorated wood framework (WF), denoted as WF-CNT, was designed as a free-standing sulfur host, achieving high sulfur loading of 10 mgs cm−2. This unique cathode featured low tortuosity microchannels and a conductive framework, reducing the diffusion paths for both ions and electrons and accommodating the volume changes associated with sulfur. Moreover, the internal CNT forests effectively captured soluble lithium polysulfides (LiPSs) and catalyze their redox kinetic. Consequently, the S@WF-CNT-800 sample exhibited a high initial discharge capacity of 1438.2 mAh g−1 at a high current density of 0.5 A g−1. Furthermore, a reversible capacity of 404.5 mAh g−1 was obtained after 500 cycles with sulfur loading of 5 mgs cm−2 at 0.5 A g−1. This work may support the development of high sulfur loading cathodes utilizing cost-effective and sustainable biomass materials for Li-S batteries.

Zn-induced formation of polymetallic carbonate hydroxide cathodes with high mass loading for high performance aqueous alkaline Zn-based batteries

Developing high mass loading cathodes with high capacity and durable life cycles is greatly worthwhile and challenging for alkaline aqueous rechargeable Zn-based batteries (AAZBs). Herein, we demonstrate an efficient zinc-induced strategy to rationally develop Zn-Ni-Co carbonate hydroxides/hydroxides heterostructure nanosheet array with an extremely high mass loading of 9.2 mg cm−2 on Ni foam (ZNC/NF) as such a superior cathode for AAZBs. It is discovered that Ni-Co hydroxide nanowires can be transformed into Zn-Ni-Co carbonate hydroxides/hydroxides heterostructure nanosheet with rich defect structures after the introduction of Zn during the synthetic process. The formed heterostructures and rich defect structures can enhance ion and electron transfer efficiency, thus ensuring the excellent electrochemical performance under high loading condition. Consequently, the ZNC/NF//Zn battery shows an outstanding areal capacity of 2.1 mAh cm−2 at 5 mA cm−2, with an ultrahigh energy density of 3.6 mWh cm−2. Moreover, the battery can still retain a high capacity of 0.42 mAh cm−2 after 5000 cycles at 50 mA cm−2, suggesting strong long-term cycling stability. This research enables pave the way for the rational design and manufacture of advanced electrode materials with large mass loadings.

Enabling Long‐term Cycling Stability of Na3V2(PO4)3/C vs. Hard Carbon Full‐cells

AbstractSodium‐ion batteries are becoming an increasingly important complement to lithium‐ion batteries. However, while extensive knowledge on the preparation of Li‐ion batteries with excellent cycling behavior exists, studies on applicable long‐lasting sodium‐ion batteries are still limited. Therefore, this study focuses on the cycling stability of batteries composed of Na3V2(PO4)3/C based cathodes and hard carbon anodes. It is shown that full‐cells with a decent stability are obtained for ethylene carbonate/propylene carbonate electrolyte and the conducting salt NaPF6. With cathode loadings of 1.2 mAh/cm2, after cell formation discharge capacities up to 92.6 mAh/g are obtained, and capacity retentions >90 % over 1000 charge/discharge cycles at 0.5 C/0.5 C are observed. It is shown that both, the additive fluoroethylene carbonate and impurities in the electrolyte, negatively affect the overall discharge capacity and cycling stability and should therefore be avoided. Remarkably, the internal resistances of well‐balanced and well‐built cells did not increase over 1500 cycles and 5 months of testing, which is a very promising result regarding the possible lifespan of the cells. The initial loss of active sodium ions in hard carbon remains a major problem, which can only be partially reduced by proper balancing.

Synthesis of N-Doped Graphene Photo-Catalyst for Photo-Assisted Charging of Li-Ion Oxygen Battery.

In this work, nitrogen (N)-doped graphene film is synthesized, as a photo-catalyst, on one side of the copper foam by chemical vapor deposition and the copper foam is directly used as an electrode after porous Pd@rGO cathode loading to the other side of the foam for the photo-assisted charging of the Li-ion oxygen battery. The amount of urea (CO(NH2)2), which is used as N atom source, is optimized to get maximum photo-anodic currents from the n-type graphene films. The optical band gap and the valance band edge potential of the optimized N-doped graphene film are determined as 2.00eV and 3.71VLi+/Li, respectively. X-ray photoelectron spectra provided that the atomic percent of N atoms in the graphene film is 1.34% and the graphitic, pyrrolic and pyridinic N atom percentages are 54.01%, 42.20% and 3.79%, respectively. The photo-assisted charging tests indicated that the N-doped graphene film photo-catalyst reduced the charging potential significantly even at 1000mAg-1 (0.1mAcm-2) current density and improved the cyclic discharge-charge performance of the Li-ion oxygen battery considerably.

Zn-In Alloying Powder Solvent Free Electrode Toward High-Load Ampere-Hour Aqueous Zn-Mn Secondary Batteries.

Aqueous Zn-ion batteries (ZIBs) are promising candidates for large-scale energy storage due to high safety, abundant reserves, low-cost, and high energy density. However, the reversibility of the metallic Zn anode in the mild electrolyte is still unsatisfactory, due to the Zn dendrite growth, hydrogen evolution, and corrosion passivation. Herein, a Zn-In alloying powder solvent free electrode is proposed to replace the Zn foil in ZIBs. The novel Zn anodes are constructed by a solvent-free manufacturing process with carbons, forming a 3D Zn deposition network and providing uniformly electric field distribution. The In on the Zn powder surface can increase the overpotential for hydrogen evolution and further improve the morphology of Zn deposition against dendrite growth. The Zn solvent-free electrodes enable the Zn-MnO2 batteries with high cathode loading mass of 10-20mg cm-2 to achieve >380 stable cycles. Furthermore, the assembled soft package batteries of 2.4 Ah (52Wh kg-2) is evaluated and the capacity retention is maintained at 80% after 200 cycles at a high areal capacity of 5 mAh cm-2 without gas evolution. This work offers a workable strategy to develop a durable Zn anode for the eventually commercial applications of aqueous Zn-Mn secondary batteries.

Effects of cathode loadings and anode protection on the performance of lithium metal batteries

While lithium-ion batteries (LIBs) are approaching their energy limits, lithium metal batteries (LMBs) are undergoing intensive investigation for higher energy density. Coupling LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode with lithium (Li) metal anode, the resultant Li||NMC811 LMBs are among the most promising technologies for future transportation electrification, which have the potential to realize an energy density two times higher than that of state-of-the-art LIBs. To maximize their energy density, the Li||NMC811 LMBs are preferred to have their cathode loading as high as possible while their Li anode as thin as possible. To this end, we investigated the effects of different cathode active material loadings (2–14 mg cm−2) on the performance of the Li||NMC811 LMBs. Our study revealed that the cathode loadings have remarkably affected the cell performance, in terms of capacity retention and sustainable capacity. Cells with high cathode loadings are more liable to fade in capacity, due to more severe formation of the CEI and more sluggish ion transport. In this study, we also verified that the protection of the Li anode is significant for achieving better cell performance. In this regard, our newly developed Li-containing glycerol (LiGL) via molecular layer deposition (MLD) is promising to help boost the cell performance, which was controllably deposited on the Li anode.

Loosely coordinating diluted highly concentrated electrolyte toward −60 °C Li metal batteries

Lithium metal batteries (LMBs) promise energy density over 400 Wh kg−1. However, they suffer severe electrochemical performance deterioration at sub-zero temperatures. Such failure behavior highly correlates to inferior lithium metal anode (LMA) compatibility and sluggish Li+ desolvation. Here, we demonstrate that cyclopentylmethyl ether (CPME) based diluted high-concentration electrolyte (DHCE) enables −60 °C LMBs operation. By leveraging the loose coordination between Li+ and CPME, such developed electrolyte boosts the formation of ion clusters to derive anion-dominant interfacial chemistry for enhancing LMA compatibility and greatly accelerates Li+ desolvation kinetics. The resulting electrolyte demonstrates high Coulombic efficiencies (CE), providing over 99.5%, 99.1%, 98.5% and 95% at 25, −20, −40, and −60 °C, respectively. The assembled Li-S battery exhibits remarkable cyclic stability in −20, and −40 °C at 0.2 C charging and 0.5 C discharging. Even at −60 °C, Li-S cell with this designed electrolyte retains > 70% of the initial capacity over 170 cycles. Besides, lithium metal coin cell and pouch cell with 10 mg cm−2 high S cathode loading exhibit cycling stability at −20 °C. This work offers an opportunity for rational designing electrolytes toward low temperature LMBs.

Regulating the anion disorder and synthesizing the low-cost and high-performance Li6−xPS5−xCl1+x solid electrolytes

Sulfide solid electrolytes have attracted wide attention due to their high ionic conductivity. Li6PS5Cl is one of the most promising electrolytes for all-solid-state lithium batteries with high-energy-density. It is reported that the disordered arrangement of Cl- in the aragonite structure has a significant effect on the conductivity of Li6PS5Cl. In this work, the disorder of anion sites is modestly regulated by adjusting the ratio of S and Cl in Li6−xPS5−xCl1+x electrolyte. In addition, to verify the commonality of this strategy, Li5.6PS4.6Cl1.4 is prepared using self-made Li2S, and similar results are obtained. On this basis, the density of Li5.6PS4.6Cl1.4 electrolyte sheet is improved by hot-pressing, which can successfully inhibit the growth of lithium dendrites. As expected, the ionic conductivity of the sulfide electrolyte and the electrochemical performance of the ASSLBs are greatly improved. A highest ionic conductivity of 8.2 × 10−3 S cm−1 of Li5.6PS4.6Cl1.4 is obtained at room temperature. A high capacity retention of 99.99 % is maintained for NCM811 @Li2O//Li5.6PS4.6Cl1.4//Li-In system after 400 cycles at 1 C with ultra-high cathode loading of 35.6 mg cm−2. Besides, the cost of sulfide electrolytes can be reduced as the decreased usage of Li2S. This work proposes a novel synthesis method of low-cost and high-performance Li6−xPS5−xCl1+x electrolytes.

Hexabutylcyclohexane‐1,2,3,4,5,6‐hexaimine Additive‐Assisted Commercial Ester Electrolyte for 4.7 V Highly‐Stable Li‐Metal Batteries

AbstractThe development of high‐energy density batteries is of utmost importance for various applications. However, the utilization of numerous high‐capacity materials is impeded by the inadequate stability of electrolytes beyond 4.5 V. This research proposes a straightforward yet highly efficient strategy to overcome this limitation and enhance the stability of interfaces in high‐voltage Li metal batteries when employing commercial ester electrolytes. A series of electrolyte additives is designed with the aim of gradually extending the length of the terminal alkyl groups of cyclohexane‐1,2,3,4,5,6‐hexaimine (CHHI). Among these additives, hexabutylcyclohexane‐1,2,3,4,5,6‐hexaimine (HBCHHI) demonstrate exceptional performance due to the synergistic complementarity of n‐butyl and imino groups. This synergistic effect leads to the formation of a thinner, denser, and LixN‐rich solid/cathode‐electrolyte interface. Accordingly, the electrolyte‐electrode interactions are suppressed, enabling Li||LiNi0.8Co0.1Mn0.1O2 (NCM811) battery operation at a high‐voltage of 4.7 V with alleviated structural degradation of cathode and even Li deposition at the anode. The capacity retention of high‐voltage Li||NCM811 cells is improved by ≈250% after 500 cycles at a rate of 5C. The lifespan of full cells is also prolonged at quasi‐practical conditions of high cathode loading of ≈2.5 mAh cm−2.

Iodine-containing additive engineering for rejuvenating inactive lithium and constructing highly stable lithium metal anodes

Inactive (‘dead’) lithium and conventional fragile solid-electrolyte interphase (SEI) usually cause performance degradation and safety hazards in Li-metal batteries. Recovering inactive lithium and constructing stable SEI are urgently required to enhance the capacity and lifespan of lithium metal batteries. Herein, we have designed a novel dual-additives electrolyte containing an I3−/I− redox couple for reviving the inactive lithium, and caffeic acid (CA) that can be anion-polymerised to modulate the composition and improve stability of the SEI. It’s found that the generated I3−/I− redox couple can turn the inactive Li2O into soluble Li+, and prompt the formation of SEI composed of inorganic LiI, Li3N and organic RCOOLi with high stability. Density functional theory (DFT) calculations indicate that the diffusion potential barrier of Li+ is significantly lower on the LiI-rich SEI interface, which can not only accelerate the transport of Li+ at the interface, but also effectively prevent I3− from attacking Li metal. Benefiting from this elaborate dual-additives electrolyte design, the symmetrical-cells present a superior electrochemical performance, i.e., high critical current density up to 10 mA cm−2, ultra-long lifespan over 7000 h at 1 mA cm−2, and over 2500 cycles under harsh conditions of high temperature (50 °C) and high current density (5 mA cm−2). In addition, as a proof of concept for practical applications of Li-metal batteries, Li|LiFePO4 full cell delivers excellent cycle stability and rate performance with low hysteresis voltage at a high cathode loading of 17.4 mg cm−2.

Implementation of Proton Exchange Membrane Water Electrolyzer with Ultralow Pt Loading Cathode through Pt Particle Size Control

Implementation of Proton Exchange Membrane Water Electrolyzer with Ultralow Pt Loading Cathode through Pt Particle Size Control

Fabrication of a 3D structure MnO2 electrode with high MnO2 mass loading as the cathode for high-performance aqueous zinc-ion batteries

Benefiting from the remarkable advantages (eco-friendly, cost-effective, and high safety) of rechargeable aqueous zinc-ion batteries (AZIBs), AZIBs are regarded as viable alternatives to traditional Lithium-ion batteries (LIBs). However, in prevailing research, the excellent electrochemical performance usually achieved by ultra-low active material loadings (e.g., <1 mg/cm²), which is far from the active material mass loading of commercial electrodes in practical (≥10 mg/cm²). Balancing superior properties with high mass loading has posed a challenge. To surmount this, an innovative method combined ultrasonic processing, freeze-drying, and 3D printing technologies is used to engineer a high MnO2 mass loading cathode for AZIBs (3D cathode). Notably, the grid structure of 3D cathode substantially augmenting the surface area for redox reactions during charge/discharge processes, which greatly enhanced the pseudo-capacitance process of cathode. Additionally, the uniform and stable microstructure exhibited the dual capability of expediting ion/electron transfer and sustaining the structural integrity throughout charge/discharge cycles. Consequently, the 3D cathode demonstrated superior comprehensive electrochemical properties at the MnO2 high mass loading of 10 mg/cm2 (138.7 mAh/g at 1 A/g, 87.4 mAh/g after 500 cycles, 82 % energy efficiency) and 15 mg/cm2 (113.3 mAh/g at 1 A/g, 56.3 mAh/g after 400 cycles, 81 % energy efficiency).

Routes to Electrochemically Stable Sulfur Cathodes for Practical Li-S Batteries.

Lithium-sulfur (Li-S) batteries have been investigated intensively as a post-Li-ion technology in the past decade; however, their realizable energy density and cycling performance are still far from satisfaction for commercial development. Although many extremely high-capacity and cycle-stable S cathodes and Li anodes are reported in literature, their use for practical Li-S batteries remains challenging due to the huge gap between the laboratory research and industrial applications. The laboratory research is usually conducted by use of a thin-film electrode with a low sulfur loading and high electrolyte/sulfur (E/S) ratios, while the practical batteries require a thick/high sulfur loading cathode and a low E/S ratio to achieve a desired energy density. To make this clear, the inherent problems of dissolution/deposition mechanism of conventional sulfur cathodes are analyzed from the viewpoint of polarization theory of porous electrode after a brief overview of the recent research progress on sulfur cathodes of Li-S batteries, and the possible strategies for building an electrochemically stable sulfur cathode are discussed for practically viable Li-S batteries from the authors' own understandings.

Dynamic Regulation of the Interfacial pH for Highly Reversible Aqueous Zinc Ion Batteries.

An electrolyte additive, with convenient operation and remarkable functions, has been regarded as an effective strategy for prolonging the cycle life of aqueous zinc ion batteries. However, it is still difficult to dynamically regulate the unstable Zn interface during long-term cycling. Herein, tricine was introduced as an efficient regulator to achieve a pH-stable and byproduct-free interface. The functional zwitterion of tricine not only inhibits interfacial pH perturbation and parasitic reactions by the trapping effect of an anionic group (-COO-) but also simultaneously creates a uniform electric field by the electrostatic shielding effect of a cationic group (-NH2+). Such synergy accordingly eliminates dendrite formation and creates a chemical equilibrium in the electrolyte, endowing the Zn||Zn cell with long-term Zn plating/stripping for 2060 h at 5 mA cm-2 and 720 h at 10 mA cm-2. As a result, the Zn||VS2 full cell under a high cathodic loading mass (8.6 mg cm-2) exhibits exceptional capacity retention of 93% after 1000 cycles.

Enhancing Lithium Stripping Efficiency in Anode-Free Solid-State Batteries through Self-Regulated Internal Pressure.

Anode-free all-solid-state lithium metal batteries (ASLMBs) promise high energy density and safety but suffer from a low initial Coulombic efficiency and rapid capacity decay, especially at high cathode loadings. Using operando techniques, we concluded these issues were related to interfacial contact loss during lithium stripping. To address this, we introduce a conductive carbon felt elastic layer that self-adjusts the pressure at the anode side, ensuring consistent lithium-solid electrolyte contact. This layer simultaneously provides electronic conduction and releases the plating pressure. Consequently, the first Coulombic efficiency dramatically increases from 58.4% to 83.7% along with a >10-fold improvement in cycling stability. Overall, this study reveals an approach for enhancing anode-free ASLMB performance and longevity by mitigating lithium stripping inefficiency through self-adjusting interfacial pressure enabled by a conductive elastic interlayer.

Highly fluorinated co-solvent enabling ether electrolyte for high-voltage lithium ion batteries with graphite anode

Conventional ether electrolytes are generally considered unsuitable for use with graphite anodes and high-voltage cathodes due to their co-intercalation with graphite and poor oxidation stability, respectively. In this work, a highly fluorinated ether molecule, 1,1,1-trifluoro-2-[(2,2,2-trifluoroethoxy) methoxy] ethane (TTME), is introduced as a co-solvent into the conventional ether system to construct a fluorinated ether electrolyte, which not only avoids the co-intercalation with graphite but also is compatible with high-voltage cathodes. Li||graphite half-cells using the fluorinated ether electrolyte deliver stable cycling with a capacity retention of 91.7% for 300 cycles. Moreover, LiNi0.8Co0.1Mn0.1O2 (NCM811)||graphite and LiCoO2 (LCO)||graphite full-cells (cathode loadings are ≈3 mAh/cm2) with the fluorinated ether electrolyte show capacity retentions of &gt; 90% over 200 cycles with a charge cut-off voltage of 4.4 V and &gt; 97% for 100 cycles with a charge cut-off voltage of 4.5 V, respectively. The dense and firm solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI) formed by the fluorinated ether electrolyte on the anode and cathode, respectively, are key to excellent cell performance. These results have significance for the subsequent application of ether electrolytes for high-voltage lithium ion batteries (up to 4.5 V) with graphite anodes.

A binder-free dry coating process for high sulfur loading cathodes of Li–S batteries: A proof-of-concept

A promising candidate for next-generation energy storage is the lithium-sulfur battery (LSB) due to its high capacity and low-cost active material (sulfur). However, the practical application of LSBs is challenged by poor cycling life and low sulfur loading. Herein, a proof-of-concept for manufacturing high load electrodes with a low-cost dry (solvent-free) coating process with a reduced carbon footprint is introduced and investigated. This process is often based on fluoropolymer-based binder additives with health and environmental concerns. Therefore, this study presents the concept of a binder-free dry coating process using sulfur/carbon black (S/CB) composites derived from a straight-forward dispersive mixing process. The electrodes are fabricated by a hot-pressing process, taking advantage of sulfur melting into a carbon matrix. To determine the process-structure-property relationships of the resulting powders, electrodes and cells, a novel structure determination by thermogravimetric analysis was used. Mixing time turns out to be an important factor, which has a significant effect on the electrode performance. The cells assembled with electrodes (⁓4.5 mgS cm−2) made from optimized powder mixtures showed a high specific capacity of about 800 mAh gS−1, and a relatively improved C-rate capability.

Interfacial Manipulation via In Situ Constructed Fast Ion Transport Channels toward an Ultrahigh Rate and Practical Li Metal Anode.

The successful substitution of Li metal for the conventional intercalation anode can promote a significant increase in the cell energy density. However, the practical application of the Li metal anode has long been fettered by the unstable solid electrolyte interface (SEI) layer on the Li metal surface and notorious dendritic Li growth. Herein, a stabilized SEI layer with in situ constructed fast ion transport channels has successfully been achieved by a robust In2S3-cemented poly(vinyl alcohol) coating. The modified Li metal demonstrates significantly enhanced Coulombic efficiency, high rate performance (10 mA cm-2), and ultralong life cycling stability (∼4900 cycles). The Li|LiCoO2 (LCO) cell presents an ultralong-term stable operation over 500 cycles at 1 C with an extremely low capacity decay rate (∼0.018% per cycle). And the Li|LCO full cell with the ultrahigh loading cathode (∼25 mg cm-2) and ultrathin Li foil (∼40 μm) also reveals a prolonged cycling performance under the low negative-to-positive capacity ratio of 2.2. Furthermore, the Li|LCO pouch cell with a commercial cathode and ultrathin Li foil still manifests excellent cycling performance even under the harsh conditions of limited Li metal and lean electrolyte. This work provides a cost-effective and scalable strategy toward high performance practical Li metal batteries.

Covalent sulfur confined in mesoporous hollow carbon spheres for effective kinetic regulation of room-temperature sodium-sulfur batteries

Room-temperature sodium-sulfur batteries have attracted extensive attention as a cost-effective and high theoretical energy density next-generation energy storage systems. However, the insulating nature of sulfur, the sluggish reactivity of sulfur with sodium, and severe dissolution of polysulfide are the main challenges of this technology. Here, we propose a covalent sulfur bond breakage mechanism by bonding of sulfur chain onto the inner cavity of the sulfydryl-functionalized mesoporous hollow carbon spheres (MHCS) to efficiently promote the generation of short-chain sodium polysulfide and accelerate polysulfide redox kinetics. The covalent sulfur confined MHCS (S@MHCS) cathode delivers an unprecedented rate capability (250 mAh g−1 at 5 C) and exhibits excellent long-term cycling stability over 1000 cycles at 1 C with a high cathode loading of 5 mg cm−2. Moreover, the associated electrochemical reaction mechanism is also revealed by ex-situ X-ray photoelectron spectroscopy and theoretical calculation. This work introduces a novel sulfur cathode design to enhance the performance of room-temperature sodium-sulfur batteries.

Enabling stable and high areal capacity solid state battery with Ni-rich cathode via failure mechanism study

Sulfide based all solid state batteries (ASSBs) with Ni-rich layered oxide cathode are one of the most promising next-generation battery technologies due to their high energy density and improved safety. However, its electrochemical performance is still unsatisfactory, especially with high cathode mass loading. Herein, the failure mechanisms of single crystal LiNi0.8Co0.1Mn0.1O2 (NCM811) in ASSBs are systematically investigated from three aspects: interfacial side reactions, micro-distribution of cathode composite and mechanical failure. In addition to the commonly reported interfacial side reactions, we find micro-heterogeneity in cathode composite has detrimental effects on electrochemical performance. Three strategies are proposed and are effective to achieve excellent electrochemical performance of the batteries: ASSBs with bare NCM811 retains 88.5 % of its capacity after 2000 cycles at 1C (1C = 200 mA g–1). Moreover, ASSBs with high cathode loading of 35.7 mg cm−2 (30 °C) and 71.4 mg cm−2 (60 °C) is explored, which deliver a record-breaking areal capacity of 6.4 mAh cm−2 and 13 mAh cm−2, respectively.