Amidst the global energy matrix transformation and escalating sustainability imperatives, sodium-ion batteries (SIBs) have attracted significant attention in the energy storage field, driven by their resource sustainability and cost competitiveness. As pivotal determinants of electrochemical performance, cathode materials govern essential metrics including specific energy density, cyclability, and operational safety in SIBs. Among these, polyanionic cathode materials have emerged as a focal research domain, distinguished by their excellent thermal and structural stability. This review systematically categorizes the types of polyanionic cathode materials and analyzes their intrinsic merits and challenges as Na hosts. To address intrinsic constrains in electronic conductivity and energy density, modification strategies encompassing lattice doping, surface coating, and nanoengineering are elucidated. Furthermore, the storage and transport mechanisms of Na+ in polyanionic compounds are revealed with the support of theoretical calculations, which provide theoretical guidance for material design. In addition, the application-specific evaluation of polyanionic cathode materials is conducted, particularly emphasizing suitability for stationary energy storage and low-speed electric vehicles. We further identify critical technical barriers and the future development directions of polyanionic cathodes for SIBs. Through a comparative study of polyanionic cathode materials, this review aims to provide a viable guide for advancing the development paradigm for cost-effective SIB technology.

Layered oxides, one of the most fascinating cathodes for sodium‐ion batteries (SIBs), have appropriate voltage window and feasible preparation process, however, cycling stability is the biggest challenge. Element doping is the most rational strategy to address this problem, but six‐coordinated octahedral radii and different radii in different valence states of these doping elements and the functions of these elements need to be taken into account. Hence, an example of P2/O3‐type Na 0.7 Mn 0.53 Ni 0.26 Fe 0.15 Mg 0.01 V 0.01 Co 0.01 Cu 0.01 Zn 0.01 Sn 0.01 O 2 (high‐entropy‐doped layered oxides, HEO) has been designed in consideration of moderate six‐coordinated octahedral radii and stabling the metal–oxygen bond. A reversible capacity of 126.9 mAh g −1 can be achieved. Even tested at 1000 mA g −1 , an improved rate performance of 72.9 mAh g −1 can be observed with a capacity retention rate of 66.5% after 1000 cycles. Potential‐based in situ electrochemical impedance spectroscopy measurements and corresponding distribution of relaxation time profiles prove the effect of multiple elemental combination. Concomitantly, in situ XRD results reveal the P2/O3 biphasic clamping reaction mechanism of HEO. Density functional theory results reveal that the multielement doping can modify the localization of electrons and enhance the structural stability. This work provides an idea of designing HEO cathode for SIBs by crystal structure modulation.

Avoiding severe structural distortion, irreversible phase transition, and realizing the stabilized multielectron redox are vital for promoting the development of high-performance NASICON-type cathode materials for sodium-ion batteries (SIBs). Herein, a high-entropy Na3.45V0.4Fe0.4Ti0.4Mn0.45Cr0.35(PO4)3 (HE-Na3.45TMP) cathode material is prepared by ultrafast high-temperature shock, which inhibits the possibility of phase separation and achieves reversible and stable multielectron transfer of 2.4/2.8 e- at voltage range of 2.0-4.45/1.5-4.45 V versus Na+/Na (the capacity of 137.2/162.0 mAh g-1). The galvanostatic charge/discharge and in-situ X-ray diffraction tests indicate the sequential redox reactions and approximate solid solution phase transition behavior of HE-Na3.45TMP. Density functional theory calculations analyze the migration pathways and energy barriers, further confirming the superior reaction kinetics of HE-Na3.45TMP. Accordingly, the HE-Na3.45TMP exhibits outstanding wide temperature applicability and can operate stably in the temperature range of -50-60 °C, accompanied by a capacity retention of 92.8% after 400 cycles at -40 °C and a capacity of 73.7 mAh g-1 even at -50 °C. The assembled hard carbon//HE-Na3.45TMP full-cell offers an energy density of ≈301 Wh kg-1 based on total cathode and anode active mass, verifying the application feasibility of HE-Na3.45TMP. This work provides an innovative and ultrafast pathway to rationally fabricate high-performance cathodes for SIBs.

Hard carbon with abundant pore structure and suitable interface has become a promising anode for sodium-ion batteries. However, it is still a challenge to accurately regulate the hard carbon micropore structure and customize the appropriate interface. Herein, different heteroatoms are introduced into the precursor to regulate the pore structure of hard carbon through its pyrolytic components, and in-situ doping is also used to optimize the interface. The results show that the hard carbon cross-linked with oxy-hybrid (HC-O) possesses affluent micropores (0.5 similar to 0.9 nm) and groups of carbonyls (C = O). The micropores can accelerate the plateau capacity, while the C = O can induce the formation of inorganic rich solid electrolyte interface (SEI) to promote initial coulombic efficiency (ICE). Benefiting from the unique structure of HC-O, the Na//HC-O half-cell exhibits high reversible capacity of 352.9 mAh g(-1) and ICE of 88.0 %. In addition, the assembled HC-O//Na3V2(PO4)(2)F-3@C full-cell reveals splendid rate performance and excellent cycling stability with capacity retention rate of 86.1 % after 300 cycles. The significance of different heteroatom cross-linked precursors on hard carbon modification is studied systematically, which provides new ideas and insights for designing hard carbon anodes of high-performance sodium-ion batteries.

Sustainability serves as a predominant obstacle for advanced energy storage. Herein, we proposed biomass-based separator materials, with favorable flame retardancy, cost-effectiveness, potential sustainability, and excellent electrochemical performance. Specifically, the engineered hydroxyapatite (HAP) molecule incorporates solvent-friendly groups to establish enhanced ion transport channels. The resulting CF@HAP separator induces an orderly decomposition of the electrolyte, which could optimize the electrode/electrolyte interface layer and prevent dendrite growth, making the durable cycling process, let alone its great mechanical properties and potential versatility. The in-depth study clarifies its complicated interfacial chemistry, flame retardancy, and thermal control mechanisms, thus achieving a "thermally closed pore" behavior during the temperature regulation process. Furthermore, the CF@HAP separator achieves complete degradation in the soil naturally within 30 days. As-designed biomass-based separators could comprehensively improve electrochemical performance toward higher levels of reactivity, stability, and postlife self-degradability, further underscoring the promising prospects for sustainable energy storage systems.

With the burgeoning demand for smart portable electronic devices and high-performance electric vehicles, there is tremendous urgency to further dramatically improve the energy density of rechargeable batteries. Although utilizing thick electrodes to improve energy density is a straightforward and productive approach, the slow reaction kinetics and inadequate mechanical strength caused by the thickness increase have hampered their development. Therefore, to break through the bottleneck of thick electrodes, we comprehensively summarize the recent progress of thick electrode architecture engineering in the field of rechargeable batteries. Considering the relationship between electrode structure and electrochemical performance, we focus on the four crucial challenges (high tortuosity, slow electron and ion transport, improper porosity, and visible cracking) and corresponding solutions (constructing vertically aligned hierarchical channels, introducing multidimensional conductive materials, regulating the degree of calendering, and so on) in constructing thick electrodes. Finally, the construction strategy of thick electrodes and the inextricable relationship of these crucial factors are summarized, and an outlook on the development and research directions toward thick electrodes is discussed, providing valuable reference for designing high-performance thick electrodes.

面向国家“双碳战略”需求，结合科技前沿和高校学生科研实践，设计了以低成本和高安全性为主要优势的锌-二氧化锰（Zn-MnO 2 ）二次电池，并形成了一个标准化的物理化学综合实验。本实验首先通过水热法制备了α-MnO 2 ，采用X射线衍射和扫描电子显微镜对制得α-MnO 2 的结构与形貌进行了表征，随后使用电池测试仪对锌片负极与α-MnO 2 正极组装成的Zn-MnO 2 锌离子电池进行了循环伏安、倍率和循环稳定性等电化学性能测试。该实验将科研热点转化为综合教学实验，从实验室走进日常生活，集化学材料合成、表征与电池电化学性能测试于一体，实验的不同模块可满足多种教学需求。此外，探究式学习与综合性操作相结合有助于提高学生的实验兴趣及化学实验操作水平；在教学过程中融入思政元素，渗透绿色理念，引导学生形成安全无污染的化学实验意识和可持续发展思想。