In Situ Growth of CoP3/Carbon Polyhedron/CoO/NF Nanoarrays as Binder‐Free Anode for Lithium‐Ion Batteries with Enhanced Specific Capacity

Advanced functional materials enable lithium‐ion batteries to reach high specific capacity. To achieve this goal, nickel foam (NF), as current collector, is chosen to in situ form aligned nanoarrays composed of CoP₃/carbon polyhedron (CP)/CoO. The CoO nanowire acts as bridge to link NF and CoP₃/CP which not only reinforces the adhesion between active material and NF but also enhances the capacity of whole electrode. Besides, CoP₃ is evenly coupled with CP, which can effectively buffer the volume expansion of CoP₃ during the charge/discharge process. Moreover, the novel architecture of CoP₃/CP/CoO/NF is beneficial to improve the electronic conductivity. As a result, the CoP₃/CP/CoO/NF anode delivers an ultrahigh specific capacity of 1715 mAh g^?1 at 0.5 A g^?1 which can remain at 1150 mAh g^?1 after 80 cycles, demonstrating the good durability. Thus, this work develops a facile strategy to design self‐supporting electrodes for an enhanced energy storage device.     

Chemically Prelithiated Hard‐Carbon Anode for High Power and High Capacity Li‐Ion Batteries

Hard carbons (HC) have potential high capacities and power capability, prospectively serving as an alternative anode material for Li‐ion batteries (LIB). However, their low initial coulombic efficiency (ICE) and the resulting poor cyclability hinder their practical applications. Herein, a facile and effective approach is developed to prelithiate hard carbons by a spontaneous chemical reaction with lithium naphthalenide (Li‐Naph). Due to the mild reactivity and strong lithiation ability of Li‐Naph, HC anode can be prelithiated rapidly in a few minutes and controllably to a desirable level by tuning the reaction time. The as‐formed prelithiated hard carbon (pHC) has a thinner, denser, and more robust solid electrolyte interface layer consisting of uniformly distributed LiF, thus demonstrating a very high ICE, high power, and stable cyclability. When paired with the current commercial LiCoO₂ and LiFePO₄ cathodes, the assembled pHC/LiCoO₂ and pHC/LiFePO₄ full cells exhibit a high ICE of >95.0% and a nearly 100% utilization of electrode‐active materials, confirming a practical application of pHC for a new generation of high capacity and high power LIBs.     

Room‐Temperature Liquid Metal Confined in MXene Paper as a Flexible,Freestanding, and Binder‐Free Anode for Next‐Generation Lithium‐Ion Batteries

Exploring flexible lithium‐ion batteries is required with the ever‐increasing demand for wearable and portable electronic devices. Selecting a flexible conductive substrate accompanying with closely coupled active materials is the key point. Here, a lightweight, flexible, and freestanding MXene/liquid metal paper is fabricated by confining 3 °C GaInSnZn liquid metal in the matrix of MXene paper without any binder or conductive additive. When used as anode for lithium‐ion cells, it can deliver a high discharge capacity of 638.79 mAh g^?1 at 20 mA g^?1. It also exhibits satisfactory rate capacities, with discharge capacities of 507.42, 483.33, 480.22, 452.30, and 404.47 mAh g^?1 at 50, 100, 200, 500, and 1000 mA g^?1, respectively. The cycling performance is obviously improved by slightly reducing the charge–discharge voltage range. The composite paper also has better electrochemical performance than liquid metal coated Cu foil. This study proposes a novel flexible anode by a clever combination of MXene paper and low‐melting point liquid metal, paving the way for next‐generation lithium‐ion batteries.     

2D Film of Carbon Nanofibers Elastically Astricted MnO Microparticles: A Flexible Binder‐Free Anode for Highly Reversible Lithium Ion Storage

MnO as anode materials has received particular interest owing to its high specific capacity, abundant resources, and low cost. However, serious problems related to the large volume change (>170%) during the lithiation/delithiation processes still results in poor rate capability and fast capacity decay. With homogenous crystals of MnO grown in the network of carbon nanofibers (CNF), binding effect of CNF can effectively weaken the volume change of MnO during cycles. In this work, a CNF/MnO flexible electrode for lithium‐ion batteries is designed and synthesized. The CNF play the roles of conductive channel and elastically astricting MnO particles during lithiation/delithiation. CNF/MnO as binder‐free anode delivers specific capacity of 983.8 mAh g^?1 after 100th cycle at a current density of 0.2 A g^?1, and 600 mAh g^?1 at 1 A g^?1 which are much better than those of pure MnO and pure CNF. The ex‐situ morphologies clearly show the relative volume change of MnO/CNF as anode under various discharging and charging times. CNF can elastically buffer the volume change of MnO during charging/discharging cycles. A facile and scalable approach for synthesizing a novel flexible binder‐free anode of CNF/MnO for potential application in highly reversible lithium storage devices is presented.     

Ultra‐light Hierarchical Graphene Electrode for Binder‐Free Supercapacitors and Lithium‐Ion Battery Anodes

A mild and environmental‐friendly method is developed for fabricating a 3D interconnected graphene electrode with large‐scale continuity. Such material has interlayer pores between reduced graphene oxide nanosheets and in‐plane pores. Hence, a specific surface area up to 835 m² g⁻¹ and a high powder conductivity up to 400 S m⁻¹ are achieved. For electrochemical applications, the interlayer pores can serve as “ion‐buffering reservoirs” while in‐plane ones act as “channels” for shortening the mass cross‐plane diffusion length, reducing the ion response time, and prevent the interlayer restacking. As binder‐free supercapacitor electrode, it delivers a specific capacitance up to 169 F g⁻¹ with surface‐normalized capacitance close to 21 μF cm⁻² (intrinsic capacitance) and power density up to 7.5 kW kg⁻¹, in 6 m KOH aqueous electrolyte. In the case of lithium‐ion battery anode, it shows remarkable advantages in terms of the initiate reversible Coulombic efficiency (61.3%), high specific capacity (932 mAh g⁻¹ at 100 mA g⁻¹), and robust long‐term retention (93.5% after 600 cycles at 2000 mAh g⁻¹).     

Ti‐Based Oxide Anode Materials for Advanced Electrochemical Energy Storage: Lithium/Sodium Ion Batteries and Hybrid Pseudocapacitors

Titanium‐based oxides including TiO₂ and M‐Ti‐O compounds (M = Li, Nb, Na, etc.) family, exhibit advantageous structural dynamics (2D ion diffusion path, open and stable structure for ion accommodations) for practical applications in energy storage systems, such as lithium‐ion batteries, sodium‐ion batteries, and hybrid pseudocapacitors. Further, Ti‐based oxides show high operating voltage relative to the deposition of alkali metal, ensuring full safety by avoiding the formation of lithium and sodium dendrites. On the other hand, high working potential prevents the decomposition of electrolyte, delivering excellent rate capability through the unique pseudocapacitive kinetics. Nevertheless, the intrinsic poor electrical conductivity and reaction dynamics limit further applications in energy storage devices. Recently, various work and in‐depth understanding on the morphologies control, surface engineering, bulk‐phase doping of Ti‐based oxides, have been promoted to overcome these issues. Inspired by that, in this review, the authors summarize the fundamental issues, challenges and advances of Ti‐based oxides in the applications of advanced electrochemical energy storage. Particularly, the authors focus on the progresses on the working mechanism and device applications from lithium‐ion batteries to sodium‐ion batteries, and then the hybrid pseudocapacitors. In addition, future perspectives for fundamental research and practical applications are discussed.