High performance Li-ion hybrid capacitors with micro-sized Nb14W3O44 as anode

Atomic Short-Range Order in a Cation-Deficient Perovskite Anode for Fast-Charging and Long-Life Lithium-Ion Batteries

Perovskite-type oxides are widely used for energy conversion and storage, but their rate-inhibiting phase transition and large volume change hinder the applications of most perovskite-type oxides for high-rate electrochemical energy storage. Here, it is shown that a cation-deficient perovskite CeNb₃ O₉ (CNO) can store a sufficient amount of lithium at a high charge/discharge rate, even when the sizes of the synthesized particles are on the order of micrometers. At 60 C (15 A g^-1 ), corresponding to a 1 min charge, the CNO anode delivers over 52.8% of its capacity. In addition, the CNO anode material exhibits 96.6% capacity retention after 2000 charge-discharge cycles at 50 C (12.5 A g^-1 ), indicating exceptional long-term cycling stability at high rates. The excellent cycling performance is attributed to the formation of atomic short-range order, which significantly prevents local and long-range structural rearrangements, stabilizing the host structure and being responsible for the small volume evolution. Moreover, the extremely high rate capacity can be explained by the intrinsically large interstitial sites in multiple directions, intercalation pseudocapacitance, atomic short-range order, and cation-vacancy-enhanced 3D-conduction networks for lithium ions. These structural characteristics and mechanisms can be used to design advanced perovskite electrode materials for fast-charging and long-life lithium-ion batteries.

Nano-Sized Niobium Tungsten Oxide Anode for Advanced Fast-Charge Lithium-Ion Batteries

The further demand for electric vehicles and smart grids prompts that the comprehensive function of lithium-ion batteries (LIBs) has been improved greatly. However, due to sluggish Li⁺ diffusion rate, thermal runway and volume expansion, the commercial graphite as an important part of LIBs is not suitable for fast-charging. Herein, nano-sized Nb₁₄ W₃ O₄₄ blocks are effectively synthesized as a fast-charge anode material. The nano-sized structure provides shorter Li⁺ diffusion pathway in the solid phase than micro-sized materials by several orders of magnitude, corresponding to accelerating the Li⁺ diffusion rate, which is beneficial for fast-charge characteristics. Consequently, Nb₁₄ W₃ O₄₄ displays excellent long-term cycling life (135 mAh g^-1 over 1000 cycles at 10 C) and rate capability at ultra-high current density (≈103.9 mAh g^-1 , 100 C) in half-cells. In situ X-ray diffraction and Raman combined with scanning electron microscopy clearly confirms the stability of crystal and microstructure. Furthermore, the fabricated Nb₁₄ W₃ O₄₄ ||LiFePO₄ full cells exhibit a remarkable power density and demonstrate a reversible specific capacity. The pouch cell delivers long cycling life (the capacity retention is as high as 96.6% at 10 C after 5000 cycles) and high-safety performance. Therefore, nano-sized Nb₁₄ W₃ O₄₄ could be recognized as a promising fast-charge anode toward next-generation practical LIBs.

Expanded Graphite-Based Materials for Supercapacitors: A Review

Supercapacitors have gained e wide attention because of high power density, fast charging and discharging, as well as good cycle performance. Recently, expanded graphite (EG) has been widely investigated as an effective electrode material for supercapacitors owing to its excellent physical, chemical, electrical, and mechanical properties. Based on charge storage mechanism, supercapacitors have been divided into symmetric, asymmetric, and hybrid supercapacitors. Here, we review the study progress of EG-based materials to be electrode materials. Furthermore, we discuss the application prospects and challenges of EG-based materials in supercapacitors.