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In the recycling process of spent lithium-ion batteries, the presence of a certain amount of aluminum ions not only increases the alkali consumption for iron and aluminum removal but also affects the purity of nickel, cobalt, manganese salts, and iron phosphate, thereby hindering the preparation of battery-grade products. Herein, the precipitation process of aluminum hydroxide from supersaturated sodium aluminate solution was investigated across varying temperatures with the addition of minimal quantity of active seeds. X-ray diffraction analysis identified gibbsite and bayerite crystallization in the active seed phases. Assessment of product particle size distribution using power spectral density indicated median particle sizes of 9.70, 18.89, 35.32, and 51.78 μm at temperatures of 45, 55, 65, and 75 °C, respectively, suggesting that elevated temperatures favored product particle size growth. Additionally, to elucidate the precipitation mechanism, the kinetic equation was augmented with the inclusion of instantaneous seed coefficient and specific surface area, yielding an apparent activation energy of 83.52 kJ/mol.

Lithium–sulfur (Li–S) batteries have high theoretical energy density and are regarded as a promising candidate for next-generation energy storage systems. However, their practical applications are hindered by the slow kinetics of sulfur conversion and polysulfide shuttling. In particular, large-scale pouch cells show much poor cyclability. Here, we develop a high-efficiency catalyst of V-doped CoSe2by studying the binary CoSe2–VSe2system and confirming its effectiveness in accelerating polysulfide conversion. The coin cell tests reveal an initial capacity of 1414 mAh g–1at 0.1 C and 1049 mAh g–1at 1 C and demonstrate 1000 times cyclability with a decaying rate of 0.05% per cycle. Furthermore, the assembly and construction of pouch cells were optimized with monolithic three-dimensional (3D) electrodes and a multistacking strategy. Specifically, a 3D metallic scaffold (3MS) was developed to host V-doped CoSe2nanowires and sulfur. In addition, Janus microspheres of C@TiO2were synthesized to capture polar polysulfides with their polar part of TiO2and adsorb nonpolar sulfur with their nonpolar part of carbon. By integrating with 3MS, C@TiO2microspheres can block all ion channels of 3MS and only allow Li ions in and out. These integral designs and monolithic structures enable multistacking pouch cells with high cyclability. A high-loading pouch cell was demonstrated with a total capacity of 700 mAh. The cell can be cycled for 70 times with a capacity retention of 65.7%. In brief, this work provides an integral strategy of catalyst design and overall 3D assembly for practical Li–S batteries in a large pouch cell format.

Metal–air batteries are a type of electrochemical cell that generates electrical energy by combining metal and oxygen from the air. They are a promising technology for energy storage and portable devices because of their high energy density, low cost, and environmental friendliness. However, the discharge products of these batteries are notoriously difficult to decompose, resulting in a high overpotential. Recent works have shown that semiconductors can capture solar energy and store it in batteries. When exposed to light, photocatalysts generate carriers (strong redox pairs), thereby increasing the electron migration rate and significantly reducing the overpotential of the metal–air battery reaction. Nevertheless, single photocatalysts often exhibit poor cycle performance due to serious carrier recombination. This review paper begins by briefly describing the fundamentals of photoelectrochemistry and then focuses on commonly used photocathode design principles and various reported photocatalysts. It also discusses the main challenges and issues caused by light, such as photocorrosion and electrolyte decomposition. Finally, the critical issues associated with photo electrodes, electrolytes, and electrode/electrolyte interfaces are emphasized, and perspectives on the development of high-performance light-assisted metal–air batteries are presented.

Enzyme catalysis enables complex biotransformation to be imitated. This biomimetic approach allows for the application of enzymes in a variety of catalytic processes. Nevertheless, enzymes need to be shielded by a support material under challenging catalytic conditions due to their intricate and delicate structures. Specifically, metal–organic frameworks and covalent–organic frameworks (MOFs and COFs) are increasingly popular for use as enzyme-carrier platforms because of their excellent tunability in structural design as well as remarkable surface modification. These porous organic framework capsules that host enzymes not only protect the enzymes against harsh catalytic conditions but also facilitate the selective diffusion of guest molecules through the carrier. This review summarizes recent progress in MOF-enzyme and COF-enzyme composites and highlights the pore structures tuned for enzyme encapsulation. Furthermore, the critical issues associated with interactions between enzymes and pore apertures on MOF- and COF-enzyme composites are emphasized, and perspectives regarding the development of high-quality MOF and COF capsules are presented.

Despite good compatibility with Li metal, garnet solid electrolytes suffer from severe electron-attack-induced Li-metal penetration and large interfacial resistance. Here, a formic acid (HCOOH)-induced electron-blocking and lithiophilic interlayer is created via a spontaneous reaction with surface Li2CO3contamination on the garnet electrolyte (LLZTO) pellet. Unlike previous methods that involved immersing LLZTO in acidic solutions, this study employs a volatile small-molecule organic acid that is easily removable, condensed, and recyclable, thus circumventing the environmental drawbacks associated with acid waste. The Li symmetric cell assembled with HCOOH-treated LLZTO exhibits a low interfacial impedance (3 Ω cm2) and a high critical current density (1.7 mA cm–2) at room temperature, enabling the cell to cycle continuously for over 1000 h at 0.2 mA cm–2. Furthermore, under a stacking pressure of 2 MPa, stable lithium plating/stripping was achieved at a current density of 0.3 mA cm–2with the assistance of HCOOH treatment. Additionally, the battery paired with a LiFePO4cathode delivers a high capacity of 151.7 mAh g–1at 1 C and maintains 88.5% of the initial capacity after 500 cycles, suggesting the feasibility of this interfacial engineering strategy for garnet-based solid Li-metal batteries.

Given the escalating global energy scarcity, there is a pressing need for advanced energy supply solutions to accommodate the evolving transportation landscape. Consequently, there has been a surge in interest surrounding lithium metal batteries, particularly Li–air batteries (LABs), which researchers have showcased for their remarkable energy density, reaching up to 3500 Wh kg–1. However, despite decades of dedicated research efforts, LABs have not yet achieved practical commercialization as a result of challenges, such as external moisture infiltration and sluggish electrochemical kinetics within the battery. In this review, we elucidate the challenges linked with oxygen-permeable membranes (OPMs) in practical LABs, particularly when operating in open environments. Subsequently, we comprehensively evaluate all developed OPMs to date, aiming to enhance the performance of LABs, focusing on both outer- and inner-type OPMs. Finally, critical issues pertaining to oxygen selectivity, permeability, water resistance, and electrolyte compatibility are underscored, with perspectives offered on the development of high-performance OPMs.

The solid-state Li-ion battery (SSB) is regarded as one of the most promising next-generation batteries due to its intrinsic safety and high energy density. Unfortunately, its development is plagued by the poor interface compatibility between the electrode and solid-state electrolyte. Herein, flame-retardant trimethyl phosphate (TMP) solvent along with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt and fuoroethylene carbonate (FEC) additive is utilized as a smart wetting agent to improve the interface compatibility between the Li-metal anode and the Li1.5Al0.5Ge1.5(PO4)3(LAGP) solid electrolyte. By taking advantage of such wetting agent, highly stable anodic and cathodic interfaces with improved physical contact and chemical stability are realized. As a result, the solid-state Li/LAGP/Li symmetrical cell with such wetting agent exhibits superior cycling performance over 1000 h with small polarization voltages. When adding such wetting agent to the solid-state Li/LAGP/LiFePO4battery, we achieved a favorable initial capacity of about 140 mAh g–1at 0.5 C and can retain 80% of its initial capacity even after 700 cycles. Additionally, the solid-state Li–air battery with such wetting agent also shows stable cycling performance over 100 h. The strategy demonstrated here will encourage more research works on developing functional and safe wetting agents for solid-state batteries.

The cycling performance of lithium–sulfur (Li–S) batteries, which is a major parameter determining the practical application of such an advanced high-energy-density battery system (1675 mA h g–1), is strongly affected by the properties of the cathodic sulfur hosts. As a desirable sulfur host, it should possess high surface area, good electronic conductivity, and superior physisorption and chemisorption to polysulfides. Here, by taking advantage of the magnesiothermic denitriding technology, the graphitic carbon nitride (GCN) with a tunable nitrogen content, surface area, and pore volume has been designed as a sulfur host for high-performance Li–S batteries. With a nitrogen content of ∼6%, a surface area of 594 m2g–1, and a pore volume of about 2 cm3g–1, the GCN-based host can retain sulfur and allow its reversible convention within cathodic region, thereby delivering a high capacity of 852.2 mA h g–1at 0.5 C with a low capacity decay of 0.12% per cycle within 300 cycles. This work provides a feasible way to design nitrogen-doped carbon materials with tunable nitrogen content and enlightens the host material design for practical Li–S batteries.

Solid-state Li-ion batteries (SSBs) have been regarded as the most promising systems to power electronic devices and electric vehicles because of their high energy density and safety. As the key component of SSBs, solid electrolytes have a substantial influence on battery performance. In recent years, polymeric composite electrolytes (PCEs) that combine polymer electrolytes with various fillers have attracted tremendous attention as a result of their high mechanical flexibility, high interfacial compatibility with electrodes, and easy processability. In this review, we provide a comprehensive summary of the recent progress in filler engineering of polymer electrolytes for SSBs. First, the challenges facing PCEs associated with the physical and chemical strategies for dispersing fillers are discussed. Then, the latest research papers regarding various fillers used in PCEs are classified and reviewed in detail. Moreover, their effects on physical and electrochemical properties, interfacial stability, and Li+-migration mechanisms are discussed, with the aim of improving the understanding of filler-reinforced PCEs for the development of SSBs.

The cycling performance of Li–O2batteries (LOBs), which is an important parameter determining the practical use of this advanced energy technology with ultrahigh energy density, is strongly affected by the nature of the oxygen electrocatalyst. As a good oxygen electrode, it should possess good activity for both the oxygen evolution reaction and the oxygen reduction reaction and superior stability under operating conditions. During the past, oxygen electrodes for LOBs were generally fabricated by loading noble metal nanoparticles on the surface of a porous carbon support. However, the nanoparticles could easily lose contact with the carbon support during the reversible liquid–gas–solid reactions that involve lithium ions, oxygen gas, and Li2O2. Herein, we reported a novel Ru-metal–organic framework (MOF)-derived carbon composite, characterized by stereoscopic Ru nanoparticle distribution within the carbon matrix, as an alternative oxygen catalyst of LOBs, enabling superior operational stability and favorable activity. More specifically, the battery demonstrated stable charge–discharge cycling for up to 800 times (∼107 days) at a current density of 500 mA g–1with low discharge/charge overpotentials (∼0.2/0.7 V vs Li). A mechanism of regenerative surface was further proposed to explain the excellent cycling stability of the LOBs through the use of the Ru-MOF–C catalyst. These encouraging results imply an accessible solution to address issues related to the oxygen catalyst for the realization of practical LOBs.

Sodium-ion batteries (SIBs) are one of the most promising alternatives to lithium-ion batteries (LIBs) due to the similar electrochemical properties of sodium and lithium and the abundance and low cost of sodium resources. Layered transition metal oxide materials are a promising kind of cathode materials because of their flexible compositions of transition metal elements and favorable specific capacities. In particular, the relatively low-cost or price-stable layered Co/Ni-free cathode oxide materials (such as Mn-, Fe-, Cr-, and V-based oxides) for SIBs show great potential to either complement or replace LIBs to meet the rapidly growing demands of clean energy due to their comparable or even superior rate and cycle performances compared with those of the layered Co/Ni-containing oxides.

The rechargeable Li–O2batteries with high theoretical specific energy are considered to be a promising energy storage system for electric vehicle application. Because of the prohibitive cost, limited supply, and weak durability of precious metals, the developments of novel metal-free catalysts become significant. Herein, the graphitic-carbon nitride@carbon papers have been produced by a facile in situ method and explored as cathodes for Li–O2batteries, which manifest considerable electrocatalytic activity toward oxygen reduction reaction and oxygen evolution reaction in nonaqueous electrolytes because of their improved electronic conductivity and high nitrogen content. The assembled Li–O2batteries using graphitic-carbon nitride@carbon papers as cathodes deliver good rate capability and cycling stability with a capacity retention of more than 100 cycles.

Redox mediators (RMs) have become a significant point in the now-established Li–O2battery system to reduce the charging overpotential in the oxygen evolution process. Nevertheless, a major inherent barrier of the RM is the redox shuttling between the Li metal anode and mobile RM, resulting in the corrosion of Li and depletion of RM. In this study, taking iodide/triiodide as a model RM, we propose an effective strategy by immersing the Li metal anode in I2steam to create a 1.5 μm thick surface protective layer. The resultant ionic conductive LiI layer on the Li metal anode can not only suppress Li dendrite growth but also act as a buffer layer between the RM and bare Li. By combining the iodide/triiodide RM with the LiI protective layer, the Li–O2battery shows low and steady charge voltage plateaus of ∼3.6 V over 70 cycles. Importantly, the symmetrical cell using the LiI-protected Li electrode exhibited small Li plating/stripping overpotentials (∼20 mV, 480 h), far superior to that of the bare Li electrode (∼70 mV, 300 h). The in situinterfacial observation shows that dendrite growth on the Li metal can be effectively suppressed by optimizing the LiI protective layer.