Sodium-ion batteries are expected to replace lithium-ion batteries in largescale energy storage systems due to their low cost, wide availability, and high abundance. Polyanionic materials are considered to be the most promising cathode materials for sodium-ion batteries because of their cycling stability and structural stability. However, limited by its poor electronic conductivity, the electrochemical performance needs to be further improved. This paper reviews the characterization and development of 3d transition metal ions polyanionic compounds, along with the summarized effect of structure and particle size on the performance and improvement of electrochemical properties. Meanwhile, crystal structure modulation, transition metal ion choice, and transition metal ion doping can improve the electrochemical performance and energy density of polyanionic compounds. Finally, this review points out the challenges of polyanionic compounds and puts forward some particular standpoints, contributing to the promising development of polyanionic compounds in the large-scale energy storage market.

Developing promising substitutes of lithium (Li) metal anode that suffers from a serious interfacial instability against the solid electrolyte (SE) is a formidable challenge for the all-solid-state battery. Aluminum (Al), a highly potential candidate owing to its high specific capacity and relatively low working potential, however, cannot withstand stable cycling in all-solid-state battery due to the fast structural collapse caused by the solid/solid contact at the Al/SE interface. Herein, a Li spreading layer consisting of metallic nickel (Ni) particles at the Al surface is proposed to raise the performance of Al anode in all-solid-state battery. Owing to the immiscibility between Ni and Li solid phases, this Li spreading layer can enable a uniform distribution of Li atoms over the electrode surface followed by a stable Li–Al alloying/dealloying processes, suppressing the stress deformation at the Al/SE interface and significantly improving the cycling performance of Al anode in all-solid-state battery. The modified Al anode not only outperforms the bare Al significantly, but also exhibits superior cyclability and rate ability compared with the Li anode. This work provides an efficient strategy to promote the application of Al anode in all-solid-state battery, and is expected to be generalized for other alloy anodes.

Sodium-ion batteries (SIBs) have attracted a lot of attention owing to their low cost, as well as similar working mechanism and manufacturing technique to lithium-ion batteries. However, the practical application of SIBs is severely hindered by limited electrode materials. Disordered carbons are reported to be promising as anode materials for SIBs. Here, for the first time, calcium lignosulfonate (LSCa), one papermaking waste, is explored as a novel low-cost precursor for carbon materials of SIBs. The optimized LSCa-derived carbon delivers a high reversible capacity of 317mAh g⁻¹ at 30mA g⁻¹ with ~60% plateau capacity, and it retains a capacity of 170mAh g⁻¹ even at 3000mA g⁻¹. These achievements are ascribed to the larger d₀₀₂ values, smaller defects, and more closed pores, compared with the original sample from the direct carbonization of LSCa.

The importance of network binder for improving cycling lifespan of silicon (Si) anode needs no further emphasis. However, the linear structure of natural polymer hardly creates a robust network binder. Herein, we propose a facile strategy of establishing a robust network binder by using small molecules of tartaric acid (TA) to locally link sodium carboxymethyl cellulose (CMC). Through hydrogen or covalent bonds, the resultant CMC-TA binder exhibits improved tensile and adhesive properties. The Si anode using CMC-TA binder delivers a satisfactory specific capacity of 2213 mAh g⁻¹ after 100 cycles at the rate of 0.2 C, with a capacity retention rate of 68.8%. This result has well confirmed the effectiveness of using small molecules to reinforce hydrogen-bonding linking between CMC and between Si particles for a high-performance Si anode.

Understanding photon energy loss caused by the charge recombination in ternary blend polymer solar cells based on nonfullerene acceptors (NFAs) is crucial for achieving further improvements in their device performance. In such a ternary system, however, the two types of donor/acceptor interface coexist, making it more difficult to analyze the photon energy loss. Here, we have focused on the origin of the voltage loss behind a high open-circuit voltage (V_OC) in ternary blend devices based on one donor polymer (poly(2,5-bis(3-(2-butyloctyl)thiophen-2-yl)-thiazolo [5,4-d]thiazole) [PTzBT]) and two acceptors, including a fullerene derivative ([6,6]- phenyl-C₆₁-butyric acid methyl ester [PCBM]) and an NFA ((2,2′-((2Z,2′Z)- (((4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydro-sindaceno[1,2-b:5,6-b′]dithiophene- 2,7-diyl)bis(4-((2-ethylhexyl)oxy)thiophene-5,2-diyl))bis(methanylylidene))bis(5,6- difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile) [IEICO- 4F]), which exhibit V_OC similar to that of fullerene-based PTzBT/PCBM binary devices. From the temperature-dependent V_OC, we found that the effective interfacial bandgap is the same between them: the PTzBT/PCBM/IEICO-4F ternary blend device is the same as the PTzBT/PCBM fullerene-based binary device rather than the PTzBT/IEICO-4F nonfullerene-based binary device. This means that the recombination center of the ternary blend device is still the interface of PTzBT/ PCBM regardless of the incorporation of a small amount of NFA. On the basis of detailed balance theory, we found that the radiative and nonradiative recombination voltage losses for PTzBT/PCBM/IEICO-4F ternary devices significantly reduced compared to those of fullerene-based PTzBT/PCBM binary counterparts. This is ascribed to the disappearance of charge transfer absorption due to overlap with the absorption of NFA and the reduction of energetic disorder due to the incorporation of NFA. Through this study, the role of NFAs in voltage loss is once again emphasized, and a ternary system capable of achieving high V_OC resulting from significantly reduced voltage loss in ternary blend solar cells is proposed. Therefore, we believe that this research proposes the guidelines that can further enhance the power conversion efficiency of polymer solar cells.

The global transition toward sustainable energy sources has prompted a paradigm shift in the field of energy storage. The separator is an important component in rechargeable batteries, which facilitates the rapid passage of ions and ensures the safety and efficiency of the electrochemical process by preventing direct contact between the anode and cathode. Traditional polyolefin-based separators induce environmental concerns due to their nonbiodegradable nature. Biomass-based separators derived from renewable sources such as plant fibers, agricultural waste, and biopolymers have emerged as promising alternatives to traditional polymer separators. In this review, we summarize the current state and development of biomass-based separators for high-performance batteries, including innovative manufacturing techniques, novel biomass materials, functionalization strategies, performance evaluation methods, and potential applications. The review also delves into the environmental impact and sustainability analysis of biomass-based separators, offering insights into the potential of biomass as the most sustainable resource for future energy storage solutions. This review could provide a holistic understanding of the advancements and potential of biomass-based separators, shedding light on the path toward sustainable and efficient energy storage based on biomass-derived separators.