Superior Electrochemical Performance Research Articles

Enhancing Orbital Interaction in Spinel LiNi0.5Mn1.5O4 Cathode for High-Voltage and High-Rate Li-Ion Batteries.

High voltage cobalt-free spinel LiNi0.5Mn1.5O4 (LNMO) is well organized as a high-power cathode material for lithium (Li)-ion batteries, however, the weak interaction between the 3d orbital of the transition metal (TM) ions and the 2p orbital of oxygen (O) leads to the instability of crystal structural, hindering the long-term stable cycling of LNMO cathode especially at high temperatures. Here, a design strategy of orbital interaction is initiated to strengthen TM 3d-O 2p framework in P-doped LNMO (P-LNMO) by choosing phytic acid as P dopant, which can realize more uniform doping compared to regular phosphate. The results show that the enhancement of TM 3d-O 2p orbital interaction in P-LNMO can suppress the Jahn-Teller effect and subsequent dissolution of Mn, as well as lowers the energy barrier for Li ion insertion/extraction kinetics. As a result, superior electrochemical performances including high discharge capacity, stable cycling behavior and enhanced rate capability of P-LNMO are obtained. Significantly, the P-LNMO pouch cell shows great cycling stability with 97.4% capacity retention after 100 cycles.

Research Progress, Challenges, and Prospects of High Energy Density Aqueous Aluminum‐Ion Batteries: A Mini‐Review

Among emerging rechargeable batteries, rechargeable aluminum‐ion batteries (AIBs) stand out for their high specific capacities and the abundance of aluminum, positioning them as an attractive electrochemical energy storage option. Despite the superior electrochemical performance of non‐aqueous AIBs, aqueous aluminum‐ion batteries (AAIBs) have garnered extensive research interest for their low cost and enhanced safety. Yet, realizing high energy density in AAIBs poses significant challenges. This article systematically reviews strategies and recent advancements in cathodes, anodes, and electrolytes aimed at achieving high energy density in AAIBs. It concludes with a forward‐looking perspective on the design of AAIBs with high energy density and prolonged cycle life, highlighting promising directions for future researches.

Cobalt‐based zeolitic imidazole framework derived hollow Co3S4 nanopolyhedrons for supercapacitors

Transition metal sulfides with designed nanostructures are expected to provide superior electrochemical performance when used as electrode materials for pseudocapacitors compared to their oxide counterparts. In this paper, hollow Co3S4 dodecahedra were successfully prepared using cobalt‐based zeolite imidazolium skeleton (ZIF‐67) as the precursor and thioacetamide (TAA) as the sulfur source combined with a facile one‐step vulcanization process. The hollow cavity structure not only shortens the carrier transport distance but also provides a higher specific surface area and abundant active sites, which promotes an efficient mass transfer process. In addition, the one‐step synthesis of hollow Co3S4 has greater advantages than the one‐step synthesis in terms of cost control and process simplification. The specific capacitance of the produced hollow Co3S4 nanopolyhedra was 668 F/g at 1 A/g and remained at 353 F/g at 10 A/g when used as a pseudocapacitor electrode, demonstrating its superior multiplication capability. In addition, the capacitance retention is 86.4% after 5000 cycles at 4 A/g, indicating its long cycle stability. Notably, employing commercial activated carbon as negative electrode and the as‐prepared hollow Co3S4 polyhedrons as positive electrode, the assembled asymmetry supercapacitor device delivers a high energy density of 20.7 Wh/kg at a power density of 716 kW/kg. The capacitance value of the device remains up to 81.4% after 2000 charging/discharging cycles. The simple synthesis process opens new opportunities to develop advanced hollow nanostructures exhibiting potential for various applications.

One-Step Molten-Salt-Assisted Approach for Direct Preparation and Regeneration of LiNi0.6Co0.2Mn0.2O2 Cathode.

Single-crystal lithium-nickel-manganese-cobalt-oxide (SC-NMC) is attracting increasing attention due to its excellent structural stability. However, its practical production faces challenges associated with complex precursor preparation processes and severe lithium-nickel cation mixing at high temperatures, which restricts its widespread application. Here, a molten-salt-assisted method is proposed using low-melting-point carbonates. This method obviates the necessity for precursor processes and simplified the synthetic procedure for SC-NMC down to a single isothermal sintering step. Multiple characterizations indicate that the acquired SC-LiNi0.6Mn0.2Co0.2O2 (SC-622) exhibits favorable structural capability against intra-granular fracture and suppressive Li+/Ni2+ cation mixing. Consequently, the SC-622 exhibits superior electrochemical performance with a high initial specific capacity (174 mAhg-1 at 0.1C, 3.0-4.3V) and excellent capacity retention (87.5% after 300 cycles at 1C). Moreover, this molten-salt-assisted method exhibits its effectiveness in directly regenerating SC-622 from spent NMC materials. The recovered material delivered a capacity of 125.4 mAhg-1 and retained 99.4% of the initial capacity after 250 cycles at 1 C. This work highlights the importance of understanding the process-structure-property relationships and can broadly guide the synthesis of other SC Ni-rich cathode materials.

Electrospun polyimide nanofiber‐based separators containing carboxyl groups for lithium‐ion batteries

AbstractA lithium‐ion battery separator facilitates lithium‐ion transportation and prevents direct contact between the cathode and anode. Polyimide separators exhibited superior thermal stability and electrolyte wettability. In this study, carboxylated polyimide separators were prepared by electrospinning carboxyl group‐containing monomers. Polyimide separators were prepared with different content of carboxyl group‐containing monomer. Moreover, the thermal property, mechanical property, and electrochemical performance of separators were studied. The carboxylated polyimide separators exhibited lower interfacial resistance and higher ionic conductivity compared with polyimide separators. Moreover, the LiFePO4/Li half‐cell assembled using the carboxylated polyimide exhibited enhanced cycling stability and rate capability. Therefore, carboxylated polyimide separators with superior electrochemical performances are promising candidates for lithium‐ion batteries.

Oxidative MnO2 Template Assisted Electrochemical Fabrication of Graphene/Polypyrrole Supercapacitor Electrodes.

Improving the morphological structure of active materials is a reliable strategy for the fabrication of high-performance supercapacitor electrodes. In this study, we introduce a feasible approach to constructing the graphene/polypyrrole (PPy) composite film implanted onto the current collector through a two-step electrochemical deposition method utilizing MnO2 as an intermediary template. The reduced graphene oxide (rGO) hydrogel film is first hydrothermally grown on a carbon cloth (CC) substrate to obtain a porous rGO@CC electrode on which MnO2 is electrodeposited. Then the as-prepared rGO/MnO2@CC electrode is subjected to the electrochemical polymerization of pyrrole, with MnO2 acting as an oxidizing template to facilitate the oxidative polymerization of pyrrole, ultimately yielding an rGO/PPy composite film on CC. The PPy synthesized via this methodology exhibits a distinctive interconnected structure, resulting in superior electrochemical performance compared with the electrode with PPy directly electrodeposited on rGO@CC. The optimized electrode achieves an impressive specific capacitance of 583.6 F g-1 at 1 A g-1 and retains 83% of its capacitance at 20 A g-1, with a capacitance loss of only 9.5% after 5000 charge-discharge cycles. The corresponding all-solid-state supercapacitor could provide a high energy density of 22.5 Wh kg-1 and a power density of 4.6 kW kg-1, with a capacitance retention of 82.7% after 5000 charge-discharge cycles. Furthermore, the device also demonstrates good flexibility performance upon bending at 90 and 180°. This work presents an innovative method for the preparation of carbon material/conducting polymer electrodes with specific structural characteristics and superior performance.

Heterostructure Engineering Enables MoSe2 with Superior Alkali-Ion Storage

Molybdenum diselenide (MoSe2) is a promising anode for alkali-ion storage due to its intrinsic advantages. However, MoSe2 still encounters the issues of structural instability and poor rate performance caused by drastic volume change and sluggish reaction kinetics. Reasonable design of electrode structure is crucial for achieving superior electrochemical performance. Herein, a novel hierarchical structure coupled with 1D/1D subunits is elaborately designed and constructed, in which the MoSe2/CoSe2 heterostructure is the “trunk” and the N-doped carbon nanotubes are the “branches” (MoSe2/CoSe2/NCNTs). Benefiting from the properties endowed by unique configurations, MoSe2/CoSe2/NCNTs electrodes manifest faster reaction kinetics and better structure durability. Evaluated as an anode for LIBs and SIBs, MoSe2/CoSe2/NCNTs deliver high reversible capacity, superior rate capability (452 at 10 A g−1 in LIBs and 296 at 10 A g−1 in SIBs), and prominent cycle life (553 after 2000 cycles at 5 A g−1 in LIBs and 310 after 2000 cycles at 5 A g−1 in SIBs). Such design conception can also provide guidance for the development of other high-performance electrodes.

Rational Design of an Optimal Al-substituted Layered Oxide Cathode for Na-ion Batteries

Layered oxide cathodes, a promising avenue for Na-ion batteries, hold the highest potential for commercialization. Herein, we delve into the structural and electrochemical properties of Al-substituted layered oxides in our quest to pinpoint the optimal cathode composition in the Na3/4(Mn-Al-Ni)O2 pseudo-ternary system. The cathode materials investigated were synthesized in three distinct phase configurations, which include two monophasic configurations with P3 and P2-type structures and a third biphasic cathode with equal proportions of P3 and P2 phases. The fractions of the P3 and P2 type phases in the cathode materials were manipulated by adjusting the calcination temperature. The varying concentration of Mn3+ and Mn4+, confirmed by X-ray photoelectron spectroscopy, was found to impact the cyclic stability of these materials significantly. During electrochemical testing, the P3 cathodes showed impressive rate performance and exhibited an excellent specific capacity of 195 mAh g−1 at 0.1C. Regarding cyclic performance, the biphasic cathodes consistently outperformed their monophasic counterparts, with P3/P2-Na0.75Mn0.50Ni0.25Al0.25O2 exhibiting 82% capacity retention after 300 cycles. Analysis of operando Synchrotron XRD data revealed an absence of P3 to O3 type phase transition in the cathodes even at low voltages where large structural variations to the unit cell structure were observed. The absence of P3 to O3 transformations and the superior electrochemical performance of Na0.75Mn0.50Ni0.25Al0.25O2 underlines the importance of Al substitution and P3/P2 biphasic structure in enhancing the electrochemical performance of layered oxides.

Unlocking the Power of Magnesium Batteries: Synergistic Effect of InSb-C Composites to Achieve Superior Electrochemical Performance.

Pure magnesium anode used in rechargeable magnesium batteries (RMB) exhibits high theoretical capacity but has been challenged by the passivation issue with conventional electrolytes. Alloy-type anodes have the potential to surpass this issue and have attracted increasing attention. However, the kinetic performance and stabilities of conventional alloy anodes are still constrained. In this study, the InSb-10%C anode is synthesized by a two-step high-energy ball milling process. The InSb-10%C anode exhibits a remarkably high capacity of up to 448 mA h g-1, significantly improved cycle performance (234 mA h g-1 at 100 cycles) and rate performance (168 mA h g-1 at 500 mA g-1). The above-mentioned superior performance of the InSb-10%C anode for RMBs is attributed to the cellular graphitized amorphous carbon composite structure (CGA) which effectively refines the particle size and restricts the volume expansion. Additionally, the reduced surface electron density of InSb combined with the high conductivity resulting from graphitization enhances the Mg2+ diffusion performance. Notably, the InSb-10%C anode demonstrates good compatibility with conventional halogen-free salt ether-based electrolytes in the full battery configuration.

Metal Organic Frameworks as Polysulfide Reaction Modulators for Lithium Sulfur Batteries: Advances and Perspectives.

Currently, lithium sulfur (Li-S) battery with high theoretical energy density has attracted great research interest. However, the diffusion and loss process of intermediate lithium polysulfide during charge-discharge hindered the application of the Li-S battery in modern life. To overcome this issue, metal organic frameworks (MOFs) and their composites have been regarded as effective additions to restrain the LiPS diffusion process for Li-S battery. Benefiting from the unique structure with rich active sites to adsorb LiPS and accelerate the LiPS redox, the Li-S batteries with MOFs modified exhibit superior electrochemical performance. Considering the rapid development of MOFs in Li-S battery, this review summarizes the recent studies of MOFs and their composites as the sulfur host materials, functional interlayer, separator coating layer, and separator/solid electrolyte for Li-S batteries in detail. In addition, the promising design strategies of functional MOF materials are proposed to improve the electrochemical performance of Li-S battery.

High-Area-Capacity Cathode by Ultralong Carbon Nanotubes for Secondary Binder-Assisted Dry Coating Technology.

Thick electrodes with high mass loading and increased content of active materials are critical for achieving higher energy density in contemporary lithium-ion batteries (LIBs). Nonetheless, producing thick electrodes through the commonly used slurry coating technology remains a formidable challenge. In this study, we have addressed this challenge by developing a dry electrode technology by using ultralong multiwalled carbon nanotubes (MWCNT) as a conductive additive and secondary binder. The mixing process of electrode compositions and the fibrillation process of the polytetrafluoroethylene (PTFE) binder were optimized. The resulting LiCoO2 (LCO) electrode exhibited a remarkable mass loading of 48 mg cm-2 and an active material content of 95 wt %. Notably, the thick LCO electrode demonstrated a superior mechanical strength and electrochemical performance. After 100 cycles at a current density of 1/3 C, the electrode still exhibited a capacity retention of 91% of its initial capacity. This dry electrode technology provides a practicable and scalable approach to the powder-to-film LIB electrode manufacturing process.

Rational design of hierarchical porous reduced graphene oxide/9,10-phenanthraquinone/porous carbon nanocomposites for high-performance supercapacitors

The development of advanced electrode material is crucial for promoting the application of new high-performance green energy storage devices and remains a great challenge. Herein, by introducing porous carbon (PC) or carbon nanotubes (CNTs) to further modify the redox-active 9,10-phenanthrenequinone (PQ) molecule non-covalently functionalized reduced graphene oxide (RGO), we have designed and synthesized RGO/PQ/PCs (RPPs) and RGO/PQ/CNTs-10 (RPC-10) nanocomposites using a simple one-step solvothermal method. Benefiting from the optimization of the hierarchical porous nanostructures and each composition further strengthens their respective advantages in the novel synthesized nanocomposites (RPPs and RPC-10), the RPPs and RPC-10 electrodes demonstrated significantly superior electrochemical energy storage performance over the RGO and RGO/PQ (RP) electrodes, especially for the RPP-10 electrode with a high specific capacitance of 343.5 F g−1 at 0.5 A g−1 and good rate capability (69.23 %, 0.5 − 40 A g−1). Furthermore, both the symmetric supercapacitor assembled with the optimal RPP-10 electrode and the hybrid supercapacitor assembled with the RPP-10 negative electrode and the NCSRC-24 positive electrode previously reported show excellent energy densities and ultra-long cycling stabilities. This result demonstrates that the synthesized novel RPP-10 nanocomposite is a highly promising candidate for new light-weight, sustainable, high-flexible and high-performance energy storage devices.

Biodegradable Activated Carbon Material Derived from Eggplant Waste for Enhanced Supercapacitor Performance

Agricultural-waste-derived porous carbon and vegetable-waste-derived porous carbon materials have been extensively studied as electrode materials for high-performance supercapacitors due to their abundance and ability to be consistently reproduced. This paper focuses on utilizing eggplant waste, the primary by-product, as a precursor for producing porous carbon through the easy carbonization and activation process. The resultant porous carbon is then employed as an electrode material for supercapacitors. The Eggplant waste-derived porous carbon exhibits a notable surface area of 1095.4 m2 g-1. This carbon material possesses the benefits of being cost-effective and environmentally friendly while exhibiting superior electrochemical performance in comparison to materials obtained from agricultural waste. The carbon electrode made from eggplant demonstrates an energy density of 9.19 Wh Kg-1 and a power density of 2880 W Kg-1, indicating its outstanding energy storage capacity.

Morphology evolution of bacterial cellulose carbon and loaded with MnO2 microspheres for high performance supercapacitors

The rapid development of economy and technology caused numerous irreversible effects on the environment, and the rational use and storage of existing resources have became an indispensable process in modern development. Energy storage through supercapacitors can effectively alleviate part of the energy crisis. Here, the effects of heating rates on the morphology of carbonized bacterial cellulose (CBC) carbon and its electrochemical properties were studied and CBC-5 (heating rate of 5 ℃/min) with porous structure was confirmed to be supporting material for loading MnO2. The specific capacitance of CBC-5@MnO2 composites was high up to 190 F g−1 at 1 A g−1, and its capacitance retention rate was up to 96.6% after 8000 cycles. The superior electrochemical performance cannot be achieved without the cooperative effect among the metal oxides and carbon materials, which also benefits from the fast transport of ions and electrons in solution. The assembled CBC-5//CBC-5@MnO2-6 h hybrid supercapacitors exhibited largest energy density and power density values of 44.5 Wh kg−1 (at 0.2 A g−1) and 11111.1 W kg−1 (at 10 A g−1), respectively. The assembled button cells can light up small LED bulbs for at least 10 min. The porous bacterial cellulose carbon can provided possibilities for high electrode design.

Nonflammable Phosphate-Based Electrolyte for Safe and Stable Potassium Batteries Enabled by Optimized Solvation Effect.

Current potassium-ion batteries (PIBs) are limited in safety and lifetime owing to the lack of suitable electrolyte solutions. To address these issues, herein, we report an innovative non-flammable electrolyte design strategy that leverages an optimal moderate solvation phosphate-based solvent which strikes a balance between solvation capability and salt dissociation ability, leading to superior electrochemical performance. The formulated electrolyte simultaneously exhibits the advantages of low salt concentration (only 0.6 M), low viscosity, high ionic conductivity, high oxidative stability, and safety. Our electrolyte also promotes the formation of self-limiting inorganic-rich interphases at the anode surface, alongside robust cathode-electrolyte interphase on iron-based Prussian blue analogues, mitigating electrode/electrolyte side reactions and preventing Fe dissolution. Notably, the PIBs employing our electrolyte exhibit exceptional durability, with 80% capacity retention after 2,000 cycles at high-voltage of 4.2 V in a coin cell. Impressively, in a larger scale pouch cell, it maintains over 81% of its initial capacity after 1,400 cycles at 1C-rate with high average Coulombic efficiency of 99.6%. This work represents a significant advancement toward the realization of safe, sustainable, and high-performance PIBs.

Investigating the effects of silicon and carbon components on the thickness evolution and performance degradation of silicon–carbon electrodes through electrochemical dilatometry

The severe volumetric changes occur during the lithiation/de-lithiation of silicon materials, which are the main cause of battery capacity failure. In this study, the expansion behavior of a cell composed of a silicon-carbon anode and Li(Ni0.5Co0.2Mn0.3)O2 (NCM523) was measured using the electrochemical dilatometry, and the contributions of different silicon and carbon components to the expansion were analyzed, along with factors affecting the cyclic stability of the silicon carbon anode. The results indicate that amorphous carbon can inhibit the volume expansion of monocrystalline silicon in the late stage of lithiation, thereby ensuring the cyclic stability of silicon. The cyclic stability of silicon-carbon composites is affected by irreversible expansion and expansion variation, and these two factors are negatively correlated. This research provides insights and guidance for the design of silicon carbon electrodes with superior electrochemical performance.

Creep-type all-solid-state cathode achieving long life

Electrochemical-mechanical coupling poses enormous challenges to the interfacial and structural stability but create new opportunities to design innovative all-solid-state batteries from scratch. Relying on the solid-solid constraint in the space-limited domain structure, we propose to exploit the lithiation-induced stress to drive the active materials creep, thereby improving the structural integrity. For demonstration, we fabricate the creep-type all-solid-state cathode using creepable Se material and an all-in-one rigid ionic/electronic conducting Mo6Se8 framework. As indicated by the in-situ experiment and numerical simulation, this cathode presents unique capabilities in improving interparticle contact and avoiding particle fracture, leading to its superior electrochemical performance, including a superior long-cycle life of more than 3000 cycles at 0.5 C and a high volumetric energy density of 2460 Wh/L at the cathode level. We believe this innovative strategy to utilize mechanics to boost the electrochemical performance could shed light on the future design of all-solid-state batteries for practical applications.

Enhancing Structural Rigidity of Ultrahigh-Ni Oxide Through Al and Nb Dual-Bulk-Doping for High-Voltage Lithium-Ion Batteries.

The pursuit of high energy densities propels the design of next-generation nickel-based layered oxide cathodes. The utilization of low-cobalt, ultrahigh-nickel layered oxide cathodes, and the extension of operating voltages promise enhanced energy density. However, stability and safety face challenges associated with nickel content, including structural degradation, lattice oxygen evolution, and thermal instability. In this study, a promising strategy of Al and Nb dual-bulk-doping is presented in high-Ni cathode materials of LiNi0.96Co0.04O2 (NC) to stabilize the bulk structure, suppress oxygen release, and attain superior electrochemical performance at high voltages. The introduction of Al and Nb effectively raises the migration energy of Ni2+ into Li sites and stabilizes lattice oxygen through strengthened Al─O and Nb─O bonds. Furthermore, the substitution of high-valence Nb ions reduces the charge depletion of lattice oxygen and induces an ordered microstructure. The Al and Nb dual-bulk-doping strategy mitigates strain and stress associated with the H2↔H3 phase transition, reducing the generation and propagation of microcracks. The resulting Li(Ni0.96Co0.04)0.985Al0.01Nb0.005O2 (NCAN) cathode exhibits superior cycling stability, with a capacity retention of 77.8% after 300 cycles, even when operating at a high-voltage of 4.4V, outperforming the NC (48.5%). This work provides a promising perspective for developing high-voltage and high-Ni cathode materials.

A Flexible and Mechanical Robust All-Solid-State Polymer Electrolyte with Microphase Separated Structure for Lithium-Ion Battery.

Polyethylene oxide (PEO)-based electrolytes are the most widely used solid polymer electrolyte (SPE) due to their high safety, excellent ability to dissociate lithium salts, low cost, and ease of preparation. However, low ionic conductivity and narrow electrochemical stability window limit their potential for further development. "Polymer-in-salt" electrolytes exhibit superior electrochemical performance; however, the high lithium salt concentration makes the SPE mechanically fragile when facing lithium dendrites. Therefore, preparing an SPE that can withstand a high concentration of lithium salt while still maintaining good mechanical properties has become a valuable challenge. In this study, a macroscopically homogeneous but nanoscopically phase-separated polymer matrix was designed as an electrolyte that can withstand a high concentration of lithium salt while retaining good mechanical properties, and this study investigated changes in the Li+ solvation structure within the electrolyte and analyzed the reasons for the simultaneous achievement of good ionic conductivity (1.02 × 10-3 S cm-1 at 60 °C) and mechanical properties (7 MPa at room temperature). The formation of large ion clusters at the phase interface and selective enrichment of lithium salt in specific regions are found to play crucial roles, and the critical current density (CCD) can reach a value of 2.2 mA cm-2. This work demonstrates a promising design approach for polymer electrolytes that achieves an optimal balance between SPE conductivity and mechanical properties through microstructure control.

Multiple uniform lithium-ion transport channels in Li6.4La3Zr1.4Ta0.6O12/Ce(OH)3 modified polypropylene composite separator for high-performance lithium metal batteries

Lithium (Li) metal anodes (LMAs) are regarded as leading technology for advanced-generation batteries due to their high theoretical capacity and favorable redox potential. However, the practical integration of LMAs into high-energy rechargeable batteries is hindered by the challenge of Li dendrite growth. In this work, nanoparticles of Li6.4La3Zr1.4Ta0.6O12 (LLZTO) loaded with Ce(OH)3 (LLZTCO) were designed and synthesized by a hydrothermal method. A functional composite separator was crafted by coating one side of a polypropylene (PP) separator with a composite electrolyte comprised of polyvinylidene fluoride (PVDF) and LLZTCO. The synergistic interactions between PVDF and LLZTCO provide numerous rapid lithium-ion (Li+) channels, facilitating the efficient redistribution of disparate Li+ flux originating from the insulated PP separator. The composite separator demonstrated an ionic conductivity (σ) of 3.68 × 10–3 S cm−1, substantial Li+ transference number (t+) of 0.73, and a high electrochemical window of 4.8 V at 25℃. Furthermore, the Li/LLZTCO@PP/Li symmetric cells demonstrated stable cycling for over 2000 h without significant dendrite formation. The Li/LiFePO4 (LFP) cells assembled with LLZTCO@PP separators exhibited a capacity retention of 91.6 % after 400 cycles at 1C. This study offers a practical approach to fabricating composite separators with enhanced safety and superior electrochemical performance.