Phosphorus/Phosphide-Based Materials for Alkali Metal-Ion Batteries

Ultra-Thin Hydrogen-Organic-Framework (HOF) Nanosheets for Ultra-Stable Alkali Ions Battery Storage

Organic frameworks-based batteries with excellent physicochemical stability and long-term high capacity will definitely reduce the cost, carbon emissions, and metal consumption and contamination. Here, an ultra-stable and ultra-thin perylene-dicyandiamide-based hydrogen organic framework (HOF) nanosheet (P-DCD) of ≈3.5 nm in thickness is developed. When applied in the cathode, the P-DCD exhibits exceptional long-term capacity retention for alkali-ion batteries (AIBs). Strikingly, for lithium-ion batteries (LIBs), at current of 2 A g-1, the large reversible capacity of 108 mA h g-1 shows no attenuation within 5 000 cycles. For sodium-ion batteries (SIBs), the related capacity retains 91.7% within 10 000 cycles compared to the initial state, significantly much more stable than conventional organic materials reported previously. Mechanism studies through ex situ and in situ experiments and theoretical density functional theory (DFT) calculations reveal that the impressive long-term performance retention originates from the large electron delocalization, fast ion diffusion, and physicochemical stability within the ultra-thin 2D P-DCD, featuring π-π and hydrogen bonding stacking, nitrogen-rich units, and low impedance. The advantageous features demonstrate that rationally designed stable and effective organic frameworks pave the way to utilizing complete organic materials for developing next-generation low-cost and highly stable energy storage batteries.

A Review on Covalent Organic Frameworks as Artificial Interface Layers for Li and Zn Metal Anodes in Rechargeable Batteries

Li and Zn metals are considered promising negative electrode materials for the next generation of rechargeable metal batteries because of their non-toxicity and high theoretical capacity. However, the uneven deposition of metal ions (Li+ , Zn2+ ) and the uncontrolled growth of dendrites result in poor electrochemical stability, unsatisfactory cycle life, and rapid capacity decay of batteries assembled with Li and Zn electrodes. Owing to the unique internal directional channels and abundant redox active sites of covalent organic frameworks (COFs), they can be used to promote uniform deposition of metal ions during stripping/electroplating through interface modification strategies, thereby inhibiting dendrite growth. COFs provide a new perspective in addressing the challenges faced by the anodes of Li metal batteries and Zn ion batteries. This article discusses the stability and types of COFs, and summarizes some novel COF synthesis methods. Additionally, it reviews the latest progress and optimization methods of using COFs for metal anodes to improve battery performance. Finally, the main challenges faced in these areas are discussed. This review will inspire future research on metal anodes in rechargeable batteries.

Simultaneous Catalytic Acceleration of White Phosphorus Polymerization and Red Phosphorus Potassiation for High-Performance Potassium-Ion Batteries

Red phosphorus (P) as an anode material of potassium-ion batteries possesses ultra-high theoretical specific capacity (1154 mAh g-1 ). However, owing to residual white P during the preparation and sluggish kinetics of K-P alloying limit its practical application. Seeking an efficient catalyst to address the above problems is crucial for the secure preparation of red P anode with high performance. Herein, through the analysis of the activation energies in white P polymerization, it is revealed that the highest occupied molecular orbital energy of I2 (-7.40 eV) is in proximity to P4 (-7.25 eV), and the lowest unoccupied molecular orbital energy of I2 molecule (-4.20 eV) is lower than that of other common non-metallic molecules (N2 , S8 , Se8 , F2 , Cl2 , Br2 ). The introduction of I2 can thus promote the breaking of the P─P bond and accelerate the polymerization of white P molecules. Besides, the ab initio molecular dynamics simulations show that I2 can enhance the kinetics of P-K alloying. The as-obtained red P/C composites with I2 deliver excellent cycling stability (358 mAh g-1 after 1200 cycles at 1 A g-1 ). This study establishes catalysis as a promising pathway to tackle the challenges of P anode for alkali metal ion batteries.

High S-doped amorphous carbon/carbon quantum dots coupled micro-frame for highly efficient potassium storage

Anode materials with excellent rate capability, capacity, and cycle life have been a challenge in obtaining cost-effective K-ion batteries (KIBs). Based on the concept of waste recycling, we prepared the S-doped (21.5%) amorphous carbon/carbon quantum dots coupled micro-frame (SCMF) by combining chemical exfoliation and S/Se-assisted carbonization. SCMF exhibited the advantages of integrating amorphous carbon and carbon quantum dots (CQDs). The CQDs serve as fast electron channels, while amorphous carbon can accommodate more large-size K-ions and mitigate volume expansion. In KIBs, SCMF maintained a high reversible capacity (414.0 mAh g-1, after 100 cycles at 100 mA g-1), a good rate capability (224.0 mAh g-1, 2000 mA g-1), and excellent capacity retention (208.9 mAh g-1, after 2000 cycles at 1000 mA g-1). The molecular dynamic simulation revealed that CQDs provided fast electron transport channels and that C, O and S atoms had suitable interactions with K, facilitating potassium storage. Moreover, the potassium-ion capacitor (PIC) assembled from SCMF and activated carbon exhibited stable electrochemical performance, proving its potential for application. The research provided valuable insights into the reuse of biomass waste in new secondary batteries.

Decorating Phosphorus Anode with SnO2 Nanoparticles To Enhance Polyphosphides Chemisorption for High-Performance Lithium-Ion Batteries

Phosphorus has been regarded as one of the most promising next-generation lithium-ion battery anode materials, because of its high theoretical specific capacity and safe working potential. However, the shuttle effect and sluggish conversion kinetics hamper its practical application. To overcome these limitations, we decorated SnO₂ nanoparticles at the surface of phosphorus using an electrostatic self-assembly method, in which SnO₂ can participate in the discharge/charge reaction, and the Li₂O formed can chemically adsorb and suppress the shuttle of soluble polyphosphides across the separator. Additionally, the Sn/Li-Sn alloy can enhance the electrical conductivity of the overall electrode. Meanwhile, the similar volume changes and simultaneous lithiation/delithiation process in phosphorus and SnO₂/Sn are beneficial for avoiding additional particle damage near two-phase boundaries. Consequently, this hybrid anode exhibits a high reversible capacity of ∼1180.4 mAh g^-1 after 120 cycles and superior high-rate performance with ∼78.5% capacity retention from 100 to 1000 mA g^-1.

P-Doping a Porous Carbon Host Promotes the Lithium Storage Performance of Red Phosphorus

Red phosphorus (RP) is a promising anode material for use in lithium-ion batteries (LIBs) due to its high theoretical specific capacity (2596 mA h g^-1). However, the practical use of RP-based anodes has been challenged by the material's low intrinsic electrical conductivity and poor structural stability during lithiation. Here, we describe a phosphorus-doped porous carbon (P-PC) and disclose how the dopant improves the Li storage performance of RP that was incorporated into the P-PC (designated as RP@P-PC). P-doping porous carbon was achieved using an in situ method wherein the heteroatom was added as the porous carbon was being formed. The phosphorus dopant effectively improves the interfacial properties of the carbon matrix as subsequent RP infusion results in high loadings, small particle sizes, and uniform distribution. In half-cells, an RP@P-PC composite was found to exhibit outstanding performance in terms of the ability to store and utilize Li. The device delivered a high specific capacitance and rate capability (1848 and 1111 mA h g^-1 at 0.1 and 10.0 A g^-1, respectively) as well as excellent cycling stability (1022 mA h g^-1 after 800 cycles at 2.0 A g^-1). Exceptional performance metrics were also measured when the RP@P-PC was used as an anode material in full cells that contained lithium iron phosphate as the cathode material. The methodology described can be extended to the preparation of other P-doped carbon materials that are employed in contemporary energy storage applications.