Deeply Reconstructed Hierarchical Ni-Co Microwire for Flexible Ni-Zn Microbattery with Excellent Comprehensive Performance.

The rise of flexible electronics calls for efficient microbatteries (MBs) with requirements in energy/power density, stability, and flexibility simultaneously. However, the ever-reported flexible MBs only display progress around certain aspects of energy loading, reaction rate, and electrochemical stability, and it remains challenging to develop a micro-power source with excellent comprehensive performance. Herein, a reconstructed hierarchical Ni-Co alloy microwire is designed to construct flexible Ni-Zn MB. Notably, the interwoven microwires network is directly formed during the synthesis process, and can be utilized as a potential microelectrode which well avoids the toxic additives and the tedious traditional powder process, thus greatly simplifying the manufacture of MB. Meanwhile, the hierarchical alloy microwire is composed of spiny nanostructures and highly active alloy sites, which contributes to deep reconstruction (≈100 nm). Benefiting from the dense self-assembled structure, the fabricated Ni-Zn MB obtained high volumetric/areal energy density (419.7 mWh cm-3 , 1.3 mWh cm-2 ), and ultrahigh rate performance extending the power density to 109.4 W cm-3 (328.3 mW cm-2 ). More surprisingly, the MB assembled by this inherently flexible microwire network is extremely resistant to bending/twisting. Therefore, this novel concept of excellent comprehensive micro-power source will greatly hold great implications for next-generation flexible electronics.

Matching CP@NCOH/NF Cathode and GH/FNP/NF Anode for High-Performance Asymmetric Supercapacitor.

It is extremely crucial to design and match high-quality cathode and anode for achieving high-performance asymmetric supercapacitors (ASCs). Herein, Co3 (PO4 )2 @NiCo-LDH/Ni foam (CP@NCOH/NF) cathode with hierarchical morphology and graphene hydrogel/Fe-Ni phosphide/Ni foam (GH/FNP/NF) anode with the robust and porous structure are elaborately designed and prepared, respectively. Owing to their unique and profitable structures, both CP@NCOH/NF and GH/FNP/NF electrodes yield the superior capacity (10760 and 2236 mC cm-2 at 2 mA cm-2 , respectively), good rate capability (63% retention at 200 mA cm-2 and 52% retention at 50 mA cm-2 , respectively), and excellent cycling stability (72% and 74% retention after 10 000 cycles, respectively). Benefiting from their matchable electrochemical performances, the configured solid-state CP@NCOH/NF//GH/FNP/NF ASC outputs both competitive energy density (80.2 Wh kg-1 /4.1 mWh cm-3 ) and power density (14563 W kg-1 /750 mW cm-3 ), companied by remarkable cyclability (71% retention after 10 000 cycles), manifesting its great promise for large-scale integrated energy-storage system.

Cellulose Nanofiber/Carbon Nanotube-Based Bicontinuous Ion/Electron Conduction Networks for High-Performance Aqueous Zn-Ion Batteries.

Despite their potential as a next-generation alternative to current state-of-the-art lithium (Li)-ion batteries, rechargeable aqueous zinc (Zn)-ion batteries still lag in practical use due to their low energy density, sluggish redox kinetics, and limited cyclability. In sharp contrast to previous studies that have mostly focused on materials development, herein, a new electrode architecture strategy based on a 3D bicontinuous heterofibrous network scaffold (HNS) is presented. The HNS is an intermingled nanofibrous mixture composed of single-walled carbon nanotubes (SWCNTs, for electron-conduction channels) and hydrophilic cellulose nanofibers (CNFs, for electrolyte accessibility). As proof-of-concept for the HNS electrode, manganese dioxide (MnO2 ) particles, one of the representative Zn-ion cathode active materials, are chosen. The HNS allows uniform dispersion of MnO2 particles and constructs bicontinuous electron/ion conduction pathways over the entire HNS electrode (containing no metallic foil current collectors), thereby facilitating the redox kinetics (in particular, the intercalation/deintercalation of Zn2+ ions) of MnO2 particles. Driven by these advantageous effects, the HNS electrode enables substantial improvements in the rate capability, cyclability (without structural disruption and aggregation of MnO2 ), and electrode sheet-based energy (91 Wh kgelectrode -1 )/power (1848 W kgelectrode -1 ) densities, which lie far beyond those achievable with conventional Zn-ion battery technologies.

Crafting Core-Shell Heterostructures with Enriched Active Centers for High-Energy-Density Symmetric Lithium-Ion Batteries.

Current research strives to create sustainable and ecofriendly organic electrode materials (OEMs) due to the rising concerns about traditional inorganic electrode materials that call for substantial resource consumption in battery manufacturing. However, OEMs often exhibit unbalanced performance, with high capacity conflicting with a long lifespan. Herein, a 2D fully conjugated covalent organic framework featuring abundant C═O and C═N groups (HTPT-COF) was strategically synthesized by coupling 2,3,7,8-tetraamino-1,4,6,9-tetraketone with hexaketocyclohexane octahydrate. It stabilizes the enriched active centers by an extended π-conjugated skeleton, thereby affording a high theoretical capacity in conjunction with potential structure stability. To further unlock the barriers of fast charge, the HTPT-COF was interwoven around highly conductive carbon nanotubes, creating a robust core-sheath heterostructure (HTPT-COF@CNT). Consequently, the crafted HTPT-COF@CNT achieves large reversible capacities of 507.7 mA h g-1, high-rate performance (247.8 mA h g-1 at 20.0 A g-1), and long-term durability (1000 cycles). Aiming to streamline the process and cut the cost of battery manufacturing, all-organic symmetric batteries were well fabricated using HTPT-COF@CNT as both cathode and anode, demonstrating high energy/power density (up to 191.7 W h kg-1 and 3800.3 W kg-1, respectively) and long-term stability over 1000 cycles. Such HTPT-COF@CNT represents a promising sustainable electrode that effectively addresses irreconcilable contradictions encountered by OEMs, boosting the development of advanced organic batteries with high capacity and cycling stability.

Advances of Carbon Materials for Dual-Carbon Lithium-Ion Capacitors: A Review.

Lithium-ion capacitors (LICs) have drawn increasing attention, due to their appealing potential for bridging the performance gap between lithium-ion batteries and supercapacitors. Especially, dual-carbon lithium-ion capacitors (DC-LICs) are even more attractive because of the low cost, high conductivity, and tunable nanostructure/surface chemistry/composition, as well as excellent chemical/electrochemical stability of carbon materials. Based on the well-matched capacity and rate between the cathode and anode, DC-LICs show superior electrochemical performances over traditional LICs and are considered to be one of the most promising alternatives to the current energy storage devices. In particular, the mismatch between the cathode and anode could be further suppressed by applying carbon nanomaterials. Although great progresses of DC-LICs have been achieved, a comprehensive review about the advances of electrode materials is still absent. Herein, in this review, the progresses of traditional and nanosized carbons as cathode/anode materials for DC-LICs are systematically summarized, with an emphasis on their synthesis, structure, morphology, and electrochemical performances. Furthermore, an outlook is tentatively presented, aiming to develop advanced DC-LICs for commercial applications.

Facile Synthesis of P-Doped Carbon Nanosheets as Janus Electrodes of Advanced Potassium-Ion Hybrid Capacitor.

Potassium-ion hybrid capacitors (PIHCs) shrewdly integrate the merits of the high energy density of battery-type anode and the high power density of capacitor-type cathode, promising prospects for potential application in a diversity of fields. Here, we report the synthesis of P-doped porous carbon nanosheets (P-PCNs) with favorable features as electrochemical storage materials, including ultrahigh specific surface area and rich activity sites. The P-PCN as Janus electrodes show highly attractive electrochemical properties of high capacity and remarkable stability for fast K+ storage and manifest high capacitance for PF6- adsorption. The P-PCNs are applied as both anode and cathode materials to set up dual-carbon PIHCs, which show the capability to deliver a high energy/power density (165.2 Wh kg-1 and 5934.4 W kg-1) as well as remarkable long-life capability.

3D Carbon Frameworks for Ultrafast Charge/Discharge Rate Supercapacitors with High Energy-Power Density.

Carbon-based electric double layer capacitors (EDLCs) hold tremendous potentials due to their high-power performance and excellent cycle stability. However, the practical use of EDLCs is limited by the low energy density in aqueous electrolyte and sluggish diffusion kinetics in organic or/and ionic liquids electrolyte. Herein, 3D carbon frameworks (3DCFs) constructed by interconnected nanocages (10-20 nm) with an ultrathin wall of ca. 2 nm have been fabricated, which possess high specific surface area, hierarchical porosity and good conductive network. After deoxidization, the deoxidized 3DCF (3DCF-DO) exhibits a record low IR drop of 0.064 V at 100 A g-1 and ultrafast charge/discharge rate up to 10 V s-1. The related device can be charged up to 77.4% of its maximum capacitance in 0.65 s at 100 A g-1 in 6 M KOH. It has been found that the 3DCF-DO has a great affinity to EMIMBF4, resulting in a high specific capacitance of 174 F g-1 at 1 A g-1, and a high energy density of 34 Wh kg-1 at an ultrahigh power density of 150 kW kg-1 at 4 V after a fast charge in 1.11 s. This work provides a facile fabrication of novel 3D carbon frameworks for supercapacitors with ultrafast charge/discharge rate and high energy-power density.