Noticeable pseudo‐capacitance behavior out of charge storage mechanism (CSM) has attracted intensive studies because it can provide both high energy density and large output power. Although cyclic voltammetry is recognized as the feasible electrochemical technique to determine it quantitatively in the previous works, the results are inferior due to uncertainty in the definitions and application conditions. Herein, three successive treatments, including de‐polarization, de‐residual and de‐background, as well as a non‐linear fitting algorithm are employed for the first time to calibrate the different CSM contribution of three typical cathode materials, LiFePO4, LiMn2O4 and Na4Fe3(PO4)2P2O7, and achieve well‐separated physical capacitance, pseudo‐capacitance and diffusive contributions to the total capacity. This work can eliminate misunderstanding concepts and correct ambiguous results of the pseudo‐capacitance contribution and recognize the essence of CSM in electrode materials.

The increasing demands for renewable energy to substitute traditional fossil fuels and related large‐scale energy storage systems (EES) drive developments in battery technology and applications today. The lithium‐ion battery (LIB), the trendsetter of rechargeable batteries, has dominated the market for portable electronics and electric vehicles and is seeking a participant opportunity in the grid‐scale battery market. However, there has been a growing concern regarding the cost and resource availability of lithium. The sodium‐ion battery (SIB) is regarded as an ideal battery choice for grid‐scale EES owing to its similar electrochemistry to the LIB and the crust abundance of Na resources. Because of the participation in frequency regulation, high pulse‐power capability is essential for the implanted SIBs in EES. Herein, a comprehensive overview of the recent advances in the exploration of high‐power cathode and anode materials for SIB is presented, and deep understanding of the inherent host structure, sodium storage mechanism, Na+ diffusion kinetics, together with promising strategies to promote the rate performance is provided. This work may shed light on the classification and screening of alternative high rate electrode materials and provide guidance for the design and application of high power SIBs in the future.

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Magnesium secondary batteries are promising candidates for large-scale energy storage systems with high safety, because of the dendrite-free electrodeposition of the magnesium anode. However, the search for available cathode materials remains a significant challenge, hindering their development. In this work, we report copper sulfide nanoparticles as high-performance cathode materials for magnesium secondary batteries, which deliver a high reversible capacity of 175 mA h g-1 at 50 mA g-1. The cathode also shows an excellent rate capability providing 90 mA h g-1 at 1000 mA g-1 and an outstanding long-term cyclability over 350 cycles. The beneficial properties are ascribed to the small-sized copper sulfide particles which facilitate the solid-state diffusion kinetics. Further investigation on the mechanism demonstrates that the reaction is a typical conversion reaction, and the excellent cycling stability is due to the CuS nanoparticles which are not facile to aggregate during cycling. This work introduces an abundant, low-cost and high-performance cathode material for magnesium secondary batteries, and provides feasibility for the practical application of magnesium secondary battery systems in large-scale energy storage devices.

Redox-active organic imides are potential alternatives to the transition-metal based cathodes for material-sustainable and environment-friendly Na-ion batteries; however, their poor cyclability remains a challenge for battery applications. To address this issue, we use a redox-active anthraquinone to link the small carbonyl molecules to obtain a conjugated polymer with multiple redox-active centers. Herein, we synthesize four cathode-active poly(anthraquinonyl imide)s (PAQIs) from pyromellitic dianhydride (or 1,4,5,8-naphthalenetetracarboxylic dianhydride) and 1,4-diaminoanthraquinone (or 1,5-diaminoanthraquinone). The as-prepared PAQI materials exhibit a high reversible capacity of 190 mAh g −1 and a stable cyclability with 93% capacity retention over 150 cycles, suggesting a possible use of these organic cathode materials for high capacity Na-ion batteries. 11 denoted in different colors. As seen in Fig. 5a, the main CV feature of PAQI-B14 (red curve) emerges as two pairs of redox peaks with similar areas at 1.42/1.58 and 1.85/2.15 V, resembling very much the CV patterns of PAQS. 8 As a reversible two-electron transfer can occur for both of pyromellitic diimide (PMDI, Fig. S2, ESI) and AQ groups,8,14,15,21,22 it is speculated that the two pairs of redox peaks of PAQI-B14 are ascribed to the stepwise two-electron transfer for both of the PMDI and AQ units. A detailed examination of the curve indicates that a shoulder oxidation peak appears at 1.95 V, which is originated from the PMDI unit. On the other hand, PAQI-B15 shows similar CV pattern (green, Fig. 5a) as PAQI-B14, but its redox peaks are better separated in the higher potential region. Hence, in the case of PAQI-B15, the redox potentials of PMDI unit are 1.35/1.65 and 1.8/2.0 V, and those of AQ unit are 1.35/1.65 and 1.9/2.25 V. Similarly, the redox potentials of PAQI-N15 can be determined. As shown in Fig. 5b, four pairs of redox peaks are observed for PAQI-N15 (orange curve) at 1.42/1.78, 1.65/2.0, 2.0/2.25, and 2.12/2.40 V. Based on the data of NTCDI 12 and AQ groups, 8 the CV peaks at 1.65/2.0 and 2.12/2.40 V can be attributed to the redox reactions of NTCDI groups, and the peaks at 1.42/1.78 and 2.0/2.25 V are given rise by the AQ groups. In comparison, PAQI-B15 and PAQI-N15 show a larger separation in the oxidation and reduction peaks, i.e, a larger polarization, than PAQI-B14 and PAQI-N14, respectively, implying that PAQI-B14and PAQI-N14 undergo their redox reactions more reversibly and easily than PAQI-B15 and PAQI-N15, most likely due to their lower steric hindrance for Na + intercalation/deintercalation. 24

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Lignin is a major component of cell wall biomass and decisively affects biomass utilisation. Engineering of lignin biosynthesis is extensively studied, while lignin modification often causes growth defects.We developed a strategy for cell-type-specific modification of lignin to achieve improvements in cell wall property without growth penalty. We targeted a lignin-related transcription factor, LTF1, for modification of lignin biosynthesis. LTF1 can be engineered to a nonphosphorylation form which is introduced into Populus under the control of either a vessel-specific or fibre-specific promoter.The transgenics with lignin suppression in vessels showed severe dwarfism and thin-walled vessels, while the transgenics with lignin suppression in fibres displayed vigorous growth with normal vessels under phytotron, glasshouse and field conditions. In-depth lignin structural analyses revealed that such cell-type-specific downregulation of lignin biosynthesis led to the alteration of overall lignin composition in xylem tissues reflecting the population of distinctive lignin polymers produced in vessel and fibre cells.This study demonstrates that fibre-specific suppression of lignin biosynthesis resulted in the improvement of wood biomass quality and saccharification efficiency and presents an effective strategy to precisely regulate lignin biosynthesis with desired growth performance.

TiO2 has been widely used as a photocatalyst and an electrode material toward the photodegradation of organic pollutants and electrochemical applications, respectively. However, the properties of TiO2 are not enough up to meet practical needs because of its intrinsic disadvantages such as a wide bandgap and low conductivity. Incorporation of carbon into the TiO2 lattice is a promising tool to overcome these limitations because carbon has metal-like conductivity, high separation efficiency of photogenerated electron/hole pairs, and strong visible-light absorption. This review would describe and discuss a variety of strategies to develop carbon-doped TiO2 with enhanced photoelectrochemical performances in environmental, energy, and catalytic fields. Emphasis is given to highlight current techniques and recent progress in C-doped TiO2-based materials. Meanwhile, how to tackle the challenges we are currently facing is also discussed. This understanding will allow the process to continue to evolve and provide facile and feasible techniques for the design and development of carbon-doped TiO2 materials.