Three-Dimensional Array of TiN@Pt₃Cu Nanowires as an Efficient Porous Electrode for the Lithium–Oxygen Battery

The nonaqueous lithium–oxygen battery is a promising candidate as a next-generation energy storage system because of its potentially high energy density (up to 2–3 kW kg^–1), exceeding that of any other existing energy storage system for storing sustainable and clean energy to reduce greenhouse gas emissions and the consumption of nonrenewable fossil fuels. To achieve high round-trip efficiency and satisfactory cycling stability, the air electrode structure and the electrocatalysts play important roles. Here, a 3D array composed of one-dimensional TiN@Pt₃Cu nanowires was synthesized and employed as a whole porous air electrode in a lithium–oxygen battery. The TiN nanowire was primarily used as an air electrode frame and catalyst support to provide a high electronic conductivity network because of the high-orientation one-dimensional crystalline structure. Meanwhile, deposited icosahedral Pt₃Cu nanocrystals exhibit highly efficient catalytic activity owing to the abundant {111} active lattice facets and multiple twin boundaries. This porous air electrode comprises a one-dimensional TiN@Pt₃Cu nanowire array that demonstrates excellent energy conversion efficiency and rate performance in full discharge and charge modes. The discharge capacity is up to 4600 mAh g^–1 along with an 84% conversion efficiency at a current density of 0.2 mA cm^–2, and when the current density increased to 0.8 mA cm^–2, the discharge capacity is still greater than 3500 mAh g^–1 together with a nearly 70% efficiency. This designed array is a promising bifunctional porous air electrode for lithium–oxygen batteries, forming a continuous conductive and high catalytic activity network to facilitate rapid gas and electrolyte diffusion and catalytic reaction throughout the whole energy conversion process

Simply Mixed Commercial Red Phosphorus and Carbon Nanotube Composite with Exceptionally Reversible Sodium-Ion Storage

Recently, sodium ion batteries (SIBs) have been given intense attention because they are the most promising alternative to lithium ion batteries for application in renewable power stations and smart grid, owing to their low cost, their abundant natural resources, and the similar chemistry of sodium and lithium. Elemental phosphorus (P) is the most promising anode materials for SIBs with the highest theoretical capacity of 2596 mA h g^–1, but the commercially available red phosphorus cannot react with Na reversibly. Here, we report that simply hand-grinding commercial microsized red phosphorus and carbon nanotubes (CNTs) can deliver a reversible capacity of 1675 mA h g^–1 for sodium ion batteries (SIBs), with capacity retention of 76.6% over 10 cycles. Our results suggest that the simply mixed commercial red phosphorus and CNTs would be a promising anode candidate for SIBs with a high capacity and low cost

Electrospun P2-type Na_2/3(Fe_1/2Mn_1/2)O₂ Hierarchical Nanofibers as Cathode Material for Sodium-Ion Batteries

Sodium-ion batteries can be the best alternative to lithium-ion batteries, because of their similar electrochemistry, nontoxicity, and elemental abundance and the low cost of sodium. They still stand in need of better cathodes in terms of their structural and electrochemical aspects. Accordingly, the present study reports the first example of the preparation of Na_2/3(Fe_1/2Mn_1/2)­O₂ hierarchical nanofibers by electrospinning. The nanofibers with aggregated nanocrystallites along the fiber direction have been characterized structurally and electrochemically, resulting in enhanced cyclability when compared to nanoparticles, with initial discharge capacity of ∼195 mAh g^–1. This is attributed to the good interconnection among the fibers, with well-guided charge transfers and better electrolyte contacts

Enhancing the High Rate Capability and Cycling Stability of LiMn₂O₄ by Coating of Solid-State Electrolyte LiNbO₃

To study the influence of solid-state electrolyte coating layers on the performance of cathode materials for lithium-ion batteries in combination with organic liquid electrolyte, LiNbO₃-coated Li_1.08Mn_1.92O₄ cathode materials were synthesized by using a facile solid-state reaction method. The 0.06LiNbO₃–0.97Li_1.08Mn_1.92O₄ cathode exhibited an initial discharge capacity of 125 mAh g^–1, retaining a capacity of 119 mAh g^–1 at 25 °C, while at 55 °C, it exhibited an initial discharge capacity of 130 mAh g^–1, retaining a capacity of 111 mAh g^–1, both at a current density of 0.5 C (where 1 C is 148 mAh g^–1). Very good rate capability was demonstrated, with the 0.06LiNbO₃–0.97Li_1.08Mn_1.92O₄ cathode showing more than 85% capacity at the rate of 50 C compared with the capacity at 0.5 C. The 0.06LiNbO₃–0.97Li_1.08Mn_1.92O₄ cathode showed a high lithium diffusion coefficient (1.6 × 10^–10 cm² s^–1 at 55 °C), and low apparent activation energy (36.9 kJ mol^–1). The solid-state electrolyte coating layer is effective for preventing Mn dissolution and maintaining the high ionic conductivity between the electrode and the organic liquid electrolyte, which may improve the design and construction of next-generation large-scale lithium-ion batteries with high power and safety

Hollow Structured Li₃VO₄ Wrapped with Graphene Nanosheets in Situ Prepared by a One-Pot Template-Free Method as an Anode for Lithium-Ion Batteries

To explore good anode materials of high safety, high reversible capacity, good cycling, and excellent rate capability, a Li₃VO₄ microbox with wall thickness of 40 nm was prepared by a one-pot and template-free in situ hydrothermal method. In addition, its composite with graphene nanosheets of about six layers of graphene was achieved. Both of them, especially the Li₃VO₄/graphene nanosheets composite, show superior electrochemical performance to the formerly reported vanadium-based anode materials. The composite shows a reversible capacity of 223 mAh g^–1 even at 20C (1C = 400 mAh g^–1). After 500 cycles at 10C there is no evident capacity fading

Facile Method To Synthesize Na-Enriched Na_1+<i>x</i>FeFe(CN)₆ Frameworks as Cathode with Superior Electrochemical Performance for Sodium-Ion Batteries

Different Na-enriched Na_1+<i>x</i>FeFe­(CN)₆ samples can be synthesized by a facile one-step method, utilizing Na₄Fe­(CN)₆ as the precursor in a different concentration of NaCl solution. As-prepared samples were characterized by a combination of synchrotron X-ray powder diffraction (S-XRD), Mössbauer spectroscopy, Raman spectroscopy, magnetic measurements, thermogravimetric analysis, X-ray photoelectron spectroscopy, and inductively coupled plasma analysis. The electrochemical results show that the Na_1.56Fe­[Fe­(CN)₆]·3.1H₂O (PB-5) sample shows a high specific capacity of more than 100 mAh g^–1 and excellent capacity retention of 97% over 400 cycles. The details structural evolution during Na-ion insertion/extraction processes were also investigated via <i>in situ</i> synchrotron XRD. Phase transition can be observed during the initial charge and discharge process. The simple synthesis method, superior cycling stability, and cost-effectiveness make the Na-enriched Na_1+<i>x</i>Fe­[Fe­(CN)₆] a promising cathode for sodium-ion batteries