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With the growing concern around the sustainability and supply of lithium, the need for alternative rechargeable energy storage technologies has become ever more pressing. Sodium-, potassium-, magnesium-, and zinc-ion batteries are fast becoming viable alternatives but are held back by capacity, rate and stability problems that have not developed comparably to lithium-ion batteries. To overcome these shortcomings and reduce the reliance on lithium, electrode materials used for these post-lithium batteries must be improved. Pre-intercalation of foreign species into the lattice of promising electrode materials can enhance their electrochemical performance in comparison to the un-pre-intercalated counterparts, closing the performance gap with lithium-ion batteries. This review article covers the common methods of pre-intercalating foreign species into electrode materials, the resulting structural effects and the improvements that are observed in the materials' electrochemical performance for post-lithium batteries. Timely and impactful work reported previously are summarised as examples of these improvements, demonstrating the value and ever-growing importance of pre-intercalation in today's battery landscape.

Present-day Li⁺ storage materials generally suffer from sluggish low-temperature electrochemical kinetics and poor high-temperature cycling stability. Herein, based on a Ca²⁺ substituted Mg₂Nb₃₄O₈₇ anode material, we demonstrate that decreasing the ionic packing factor is a two-fold strategy to enhance the low-temperature electrochemical kinetics and high-temperature cyclic stability. The resulting Mg_1.5Ca_0.5Nb₃₄O₈₇ shows the smallest ionic packing factor among Wadsley–Roth niobate materials. Compared with Mg₂Nb₃₄O₈₇, Mg_1.5Ca_0.5Nb₃₄O₈₇ delivers a 1.6 times faster Li​⁺ ​diffusivity at −20 ​°C, leading to 56% larger reversible capacity and 1.5 times higher rate capability. Furthermore, Mg_1.5Ca_0.5Nb₃₄O₈₇ exhibits an 11% smaller maximum unit-cell volume expansion upon lithiation at 60 ​°C, resulting in better cyclic stability; at 10C after 500 cycles, it has a 7.1% higher capacity retention, and its reversible capacity at 10C is 57% larger. Therefore, Mg_1.5Ca_0.5Nb₃₄O₈₇ is an all-climate anode material capable of working at harsh temperatures, even when its particle sizes are in the order of micrometers.

Optoelectronic artificial synapses (OEASs) are essential for realizing artificial neural networks (ANNs) in next-generation information processing that has high transmission speed, high bandwidth, and low power consumption. Two-dimensional (2D) materials endowed with strong light-matter interactions and atomically thin dangling-bond-free surfaces are candidates for achieving versatile optoelectronics. Developing 2D OEASs for future neuromorphic applications is significant to break the bottleneck of von Neumann architecture and achieve future artificial intelligence systems. This review primarily focuses on recent developments in advanced 2D OEASs, discussing their working mechanism as well as potential applications. Common materials, device structures, and their synthesis and construction methods are also summarized. Finally, the prospects for future 2D OEASs from the perspectives of materials, performance, and applications are briefly described.

Ultra-thick, dense alloy-type anodes are promising for achieving large areal and volumetric performance in potassium-ion batteries (PIBs), but severe volume expansion as well as sluggish ion and electron diffusion kinetics heavily impede their widespread application. Herein, we design highly dense (3.1 ​g ​cm⁻³) Ti₃C₂T_x MXene and graphene dual-encapsulated nano-Sb monolith architectures (HD-Sb@Ti₃C₂T_x-G) with high-conductivity elastic networks (1560 ​S ​m⁻¹) and compact dually encapsulated structures, which exhibit a large volumetric capacity of 1780.2 ​mAh cm⁻³ (gravimetric capacity: 565.0 ​mAh g⁻¹), a long-term stable lifespan of 500 cycles with 82% retention, and a large areal capacity of 8.6 ​mAh cm⁻² (loading: 31 ​mg ​cm⁻²) in PIBs. Using ex-situ SEM, in-situ TEM, kinetic investigations, and theoretical calculations, we reveal that the excellent areal and volumetric performance mechanism stems from the three dimensional (3D) high-conductivity elastic networks and the dual-encapsulated Sb architecture of Ti₃C₂T_x and graphene; these effectively mitigate against volume expansion and the pulverization of Sb, offering good electrolyte penetration and rapid ionic/electronic transmission. Ti₃C₂T_x also decreases the K⁺ diffusion energy barrier, and the ultra-thick compact electrode ensures volumetric and areal performance. These findings provide a feasible strategy for fabricating ultra-thick, dense alloy-type electrodes to achieve high areal and volumetric capacity energy storage via highly-dense, dual-encapsulated architectures with conductive elastic networks.

Developing cost-effective and reliable solid-state sodium batteries with superior performance is crucial for stationary energy storage. A key component in facilitating their application is a solid-state electrolyte with high conductivity and stability. Herein, we employed aliovalent cation substitution to enhance ionic conductivity while preserving the crystal structure. Optimized substitution of Y³⁺ with Zr⁴⁺ in Na₅YSi₄O₁₂ introduced Na⁺ ​ion vacancies, resulting in high bulk and total conductivities of up to 6.5 and 3.3 ​mS ​cm⁻¹, respectively, at room temperature with the composition Na_4.92Y_0.92Zr_0.08Si₄O₁₂ (NYZS). NYZS shows exceptional electrochemical stability (up to 10 ​V vs. Na⁺/Na), favorable interfacial compatibility with Na, and an excellent critical current density of 2.4 ​mA ​cm⁻². The enhanced conductivity of Na⁺ ​ions in NYZS was elucidated using solid-state nuclear magnetic resonance techniques and theoretical simulations, revealing two migration routes facilitated by the synergistic effect of increased Na⁺ ​ion vacancies and improved chemical environment due to Zr⁴⁺ substitution. NYZS extends the list of suitable solid-state electrolytes and enables the facile synthesis of stable, low-cost Na⁺ ion silicate electrolytes.

Nonaqueous Li metal batteries (LMBs) and aqueous Zn metal batteries (ZMBs) are promising next-generation secondary batteries owing to their high energy density. Selecting an appropriate electrolyte is critical for addressing the safety issues nonaqueous and aqueous metal batteries can encounter. Ionic liquids (ILs) have been widely used in secondary metal batteries because they are non-flammable, present good thermal stability, and have wide electrochemical windows. This review highlights the research progress on IL-based electrolytes for stable Li/Zn metal anodes. We focus particularly on these electrolytes' electrochemistry and functionalities at the electrolyte/anode interface for inhibiting dendrite growth, preventing side reactions, and enhancing electrochemical performance. It is expected that this review will shed some light on the development of ILs for next-generation metal batteries.

Alongside the pursuit of high energy density and long service life, the urgent demand for low-temperature performance remains a long-standing challenge for a wide range of Li-ion battery applications, such as electric vehicles, portable electronics, large-scale grid systems, and special space/seabed/military purposes. Current Li-ion batteries suffer a major loss of capacity and power and fail to operate normally when the temperature decreases to −20 ​°C. This deterioration is mainly attributed to poor Li-ion transport in a bulk carbonated ester electrolyte and its derived solid–electrolyte interphase (SEI). In this mini-review discussing the limiting factors in the Li-ion diffusion process, we propose three basic requirements when formulating electrolytes for low-temperature Li-ion batteries: low melting point, poor Li⁺ affinity, and a favorable SEI. Then, we briefly review emerging progress, including liquefied gas electrolytes, weakly solvating electrolytes, and localized high-concentration electrolytes. The proposed novel electrolytes effectively improve the reaction kinetics via accelerating Li-ion diffusion in the bulk electrolyte and interphase. The final part of the paper addresses future challenges and offers perspectives on electrolyte designs for low-temperature Li-ion batteries.

Electrocatalytic CO₂ reduction (ECR) to high-value fuels and chemicals offers a promising conversion technology for achieving sustainable carbon cycles. In recent years, although great efforts have been made to develop high-efficiency ECR catalysts, challenges remain in achieving high activity and long durability simultaneously. Taking advantage of the adjustable structure, tunable component, and the M–Ch (M ​= ​Sn, In, Bi, etc., Ch ​= ​S, Se, Te) covalent bonds stabilized metal centers, the p-block metal chalcogenides (PMC) based electrocatalysts have shown great potential in converting CO₂ into CO or formates. In addition, the unique p-block electron structure can suppress the competitive hydrogen evolution reaction and enhance the adsorption of ECR intermediates. Seeking to systematically understand the structure–activity relationship of PMC-based ECR catalysts, this review summarizes the recent advances in designing PMC electrocatalysts for CO₂ reduction based on the fundamental aspects of heterogeneous ECR process, including advanced strategies for optimizing the intrinsic activity and improving the loading density of catalytic sites, constructing highly stable catalysts, and tuning product selectivities. Subsequently, we outline the challenges and perspectives on developing high-performance PMC ECR catalysts for practical applications.

Organic optoelectronic materials enable cutting-edge, low-cost organic photodiodes, including organic solar cells (OSCs) for energy conversion and organic photodetectors (OPDs) for image sensors. The bulk heterojunction (BHJ) structure, derived by blending donor and acceptor materials in a single solution, has dominated in the construction of active layer, but its morphological evolution during film formation poses a great challenge for obtaining an ideal nanoscale morphology to maximize exciton dissociation and minimize nongeminate recombination. Solution sequential deposition (SSD) can deliver favorable p–i–n vertical component distribution with abundant donor/acceptor interfaces and relatively neat donor and acceptor phases near electrodes, making it highly promising for excellent device performance and long-term stability. Focusing on the p–i–n structure, this review provides a systematic retrospect on regulating this morphology in SSD by summarizing solvent selection and additive strategies. These methods have been successfully implemented to achieve well-defined morphology in ternary OSCs, all-polymer solar cells, and OPDs. To provide a practical perspective, comparative studies of device stability with BHJ and SSD film are also discussed, and we review influential progress in blade-coating techniques and large-area modules to shed light on industrial production. Finally, challenging issues are outlined for further research toward eventual commercialization.

Bismuth sulfide (Bi₂S₃) is a dominant anode material for sodium-ion batteries due to its high theoretical capacity. However, extreme volume fluctuations as well as low electrical conductivity and reaction kinetics still limit its practical applications. Herein, we construct an abundant heterointerface of Bi/Bi₂S₃ by engineering the structure of Bi nanoparticles embedded on Bi₂S₃ nanorods (denoted as Bi–Bi₂S₃ NRs) to effectively solve the abovementioned obstacles. Theoretical and systematic characterization results reveal that the constructed heterointerface of Bi/Bi₂S₃ has a built-in electric field, significantly boosts the electrical conductivity, enhances the Na⁺ diffusion kinetics, and buffers the volume variation. With this modification, it can deliver long cycling life, with an ultra-high capacity of 500 mAh g⁻¹ over 500 cycles at 1 ​A ​g⁻¹, and outstanding rate capability, with a capacity of 456 mAh g⁻¹ even at 15 ​A ​g⁻¹. Moreover, a full cell can achieve a high energy density of 180 ​Wh kg⁻¹ at a power density of 40 ​W ​kg⁻¹. Our research opens up a fresh path for improving the dynamics and structural stability of metal sulfide-based electrode materials for SIBs.