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2025 Volume 41 Issue 8
2025, 41(8): 100094
doi: 10.1016/j.actphy.2025.100094
Abstract:
The rapid development of emerging fields such as electric vehicles, drones, and robotics has driven the demand for secondary batteries with higher energy density and enhanced safety. The lithium metal anode (LMA) is widely regarded as an ideal anode material for next-generation rechargeable batteries due to its high specific capacity (3860 mAh·g−1) and low redox potential (−3.04 V vs. standard hydrogen electrode). However, LMA faces significant challenges, primarily the uncontrollable growth of dendrites and its inherent propensity for thermal runaway. To address these issues, this study proposes a novel silsesquioxane-functionalized hexaphenoxycyclotriphosphazene (HPCTP)-based porous polymer (SHPP) artificial interphase layer, synthesized via Friedel-Crafts alkylation, to achieve highly stable LMA performance. N2 adsorption/desorption analysis confirms that SHPP features a hierarchical nanoporous structure, with pores of approximately 0.5 and 0.6 nm that effectively restrict the mobility of PF6− anions. As a result, the Li-ion transference number increases from 0.29 in liquid electrolytes to 0.60, which helps suppress Li dendrite growth. Additionally, the rich nanoporous structure of SHPP significantly improves its wettability with the electrolyte. In situ thermogravimetric analysis coupled with Fourier transform infrared spectroscopy (TG-FTIR) reveals that SHPP decomposes at approximately 410 ℃, generating phosphate radicals (PO•) that quench highly reactive hydroxyl (HO•) and oxygen (O•) radicals produced during the thermal decomposition of ester-based electrolytes, effectively mitigating thermal runaway risks. Thermal analysis and ignition tests confirm the outstanding thermal stability and flame-retardant properties of SHPP. Semi-in situ X-ray photoelectron spectroscopy (XPS) analysis indicates that the solid electrolyte interphase (SEI) on bare Li metal is predominantly organic and undergoes significant compositional fluctuations during cycling. In contrast, the SEI formed on SHPP-Li is enriched with Li phosphide (Li3P), which enhances ionic conductivity, and Li fluoride (LiF), which improves chemical stability, resulting in a compositionally stable SEI throughout cycling. SHPP not only facilitates interfacial Li-ion transport but also promotes the formation of a chemically robust interphase. In situ optical microscopy and semi-in situ field-emission scanning electron microscopy (FE-SEM) images demonstrate that the SHPP artificial interphase effectively suppresses Li dendrite growth, enabling uniform Li deposition. As a result, SHPP-Li||SHPP-Li symmetric cells exhibit stable cycling for 1,600 h at 0.5 mA·cm−2 and 0.5 mAh·cm−2. Furthermore, SHPP-Li||LiNi0.8Co0.1Mn0.1O2 full cells maintain a high capacity retention of 76.8% after 500 cycles at 1C (1C = 190 mA·g−1). This flame-retardant artificial interphase layer offers a promising strategy for designing dendrite-free and safe LMAs. ![]()
The rapid development of emerging fields such as electric vehicles, drones, and robotics has driven the demand for secondary batteries with higher energy density and enhanced safety. The lithium metal anode (LMA) is widely regarded as an ideal anode material for next-generation rechargeable batteries due to its high specific capacity (3860 mAh·g−1) and low redox potential (−3.04 V vs. standard hydrogen electrode). However, LMA faces significant challenges, primarily the uncontrollable growth of dendrites and its inherent propensity for thermal runaway. To address these issues, this study proposes a novel silsesquioxane-functionalized hexaphenoxycyclotriphosphazene (HPCTP)-based porous polymer (SHPP) artificial interphase layer, synthesized via Friedel-Crafts alkylation, to achieve highly stable LMA performance. N2 adsorption/desorption analysis confirms that SHPP features a hierarchical nanoporous structure, with pores of approximately 0.5 and 0.6 nm that effectively restrict the mobility of PF6− anions. As a result, the Li-ion transference number increases from 0.29 in liquid electrolytes to 0.60, which helps suppress Li dendrite growth. Additionally, the rich nanoporous structure of SHPP significantly improves its wettability with the electrolyte. In situ thermogravimetric analysis coupled with Fourier transform infrared spectroscopy (TG-FTIR) reveals that SHPP decomposes at approximately 410 ℃, generating phosphate radicals (PO•) that quench highly reactive hydroxyl (HO•) and oxygen (O•) radicals produced during the thermal decomposition of ester-based electrolytes, effectively mitigating thermal runaway risks. Thermal analysis and ignition tests confirm the outstanding thermal stability and flame-retardant properties of SHPP. Semi-in situ X-ray photoelectron spectroscopy (XPS) analysis indicates that the solid electrolyte interphase (SEI) on bare Li metal is predominantly organic and undergoes significant compositional fluctuations during cycling. In contrast, the SEI formed on SHPP-Li is enriched with Li phosphide (Li3P), which enhances ionic conductivity, and Li fluoride (LiF), which improves chemical stability, resulting in a compositionally stable SEI throughout cycling. SHPP not only facilitates interfacial Li-ion transport but also promotes the formation of a chemically robust interphase. In situ optical microscopy and semi-in situ field-emission scanning electron microscopy (FE-SEM) images demonstrate that the SHPP artificial interphase effectively suppresses Li dendrite growth, enabling uniform Li deposition. As a result, SHPP-Li||SHPP-Li symmetric cells exhibit stable cycling for 1,600 h at 0.5 mA·cm−2 and 0.5 mAh·cm−2. Furthermore, SHPP-Li||LiNi0.8Co0.1Mn0.1O2 full cells maintain a high capacity retention of 76.8% after 500 cycles at 1C (1C = 190 mA·g−1). This flame-retardant artificial interphase layer offers a promising strategy for designing dendrite-free and safe LMAs.
2025, 41(8): 100085
doi: 10.1016/j.actphy.2025.100085
Abstract:
Benefiting from the synergistic participation of transition metals (TMs) and lattice oxygen in redox reactions, Li-rich layered oxides (LLOs) exhibit a capacity exceeding 250 mAh·g−1, positioning them as promising cathode candidates for next-generation high-energy-density lithium-ion batteries. To further enhance capacity and reduce reliance on environmentally hazardous Co and Ni elements, the development of high-Mn LLOs (HM-LLOs) with ultrahigh capacities surpassing 350 mAh·g−1 has emerged as a viable strategy. Elevated Mn content introduces additional Li–O–Li configurations, facilitating greater lattice oxygen involvement in redox reactions, thereby increasing theoretical capacity. However, practical studies reveal that the achievable capacity of HM-LLOs remains significantly lower than theoretical predictions, severely hindering their application. The discrepancy primarily stems from two factors: activation difficulty and irreversible oxygen loss. Despite the higher initial charge capacity, the lattice oxygen utilization efficiency is still limited by incomplete activation. Meanwhile, irreversible oxygen loss leads to low initial coulombic efficiency (ICE). Given these challenges in HM-LLOs, a systematic review is necessary to unravel the origin of these issues and seek valid strategies to promote their application in power batteries. Herein, we elucidate the relationship between high Mn content and theoretical capacity through compositional, structural, and stoichiometric perspectives. Next, we analyze the roles of elemental components in HM-LLOs at the atomic level, followed by an in-depth investigation of unique structural evolution, particularly the formation of large Li2MnO3 domains. These factors collectively restrict practical capacity utilization. Low Co content combined with large Li2MnO3 domains exacerbate activation issues, while low Ni content and these domains promote irreversible oxygen loss. Building on this mechanistic understanding, we comprehensively categorize various strategies, from precursor synthesis to active material modifications. The mechanisms of precursor synthesis and structural transformations during the sintering process have been detailed. Optimization methods employed during the synthesis process have been thoroughly reviewed. Furthermore, effective modification methods have been elaborated, from the fundamental principles to practical applications. The advantages and disadvantages of these modification methods, as well as potential future optimization directions, have been outlined. Additionally, novel explorations, such as the construction of O2-type structures, innovative activation methods, and the development of sulfur-based host, are discussed. Finally, we propose future directions to bridge the gap between theoretical and practical capacities, including advanced characterization of oxygen redox dynamics and machine learning-guided evaluation of modifications. This review provides critical insights into advancing high-capacity cathode materials, thus accelerating the commercialization of HM-LLOs. ![]()
Benefiting from the synergistic participation of transition metals (TMs) and lattice oxygen in redox reactions, Li-rich layered oxides (LLOs) exhibit a capacity exceeding 250 mAh·g−1, positioning them as promising cathode candidates for next-generation high-energy-density lithium-ion batteries. To further enhance capacity and reduce reliance on environmentally hazardous Co and Ni elements, the development of high-Mn LLOs (HM-LLOs) with ultrahigh capacities surpassing 350 mAh·g−1 has emerged as a viable strategy. Elevated Mn content introduces additional Li–O–Li configurations, facilitating greater lattice oxygen involvement in redox reactions, thereby increasing theoretical capacity. However, practical studies reveal that the achievable capacity of HM-LLOs remains significantly lower than theoretical predictions, severely hindering their application. The discrepancy primarily stems from two factors: activation difficulty and irreversible oxygen loss. Despite the higher initial charge capacity, the lattice oxygen utilization efficiency is still limited by incomplete activation. Meanwhile, irreversible oxygen loss leads to low initial coulombic efficiency (ICE). Given these challenges in HM-LLOs, a systematic review is necessary to unravel the origin of these issues and seek valid strategies to promote their application in power batteries. Herein, we elucidate the relationship between high Mn content and theoretical capacity through compositional, structural, and stoichiometric perspectives. Next, we analyze the roles of elemental components in HM-LLOs at the atomic level, followed by an in-depth investigation of unique structural evolution, particularly the formation of large Li2MnO3 domains. These factors collectively restrict practical capacity utilization. Low Co content combined with large Li2MnO3 domains exacerbate activation issues, while low Ni content and these domains promote irreversible oxygen loss. Building on this mechanistic understanding, we comprehensively categorize various strategies, from precursor synthesis to active material modifications. The mechanisms of precursor synthesis and structural transformations during the sintering process have been detailed. Optimization methods employed during the synthesis process have been thoroughly reviewed. Furthermore, effective modification methods have been elaborated, from the fundamental principles to practical applications. The advantages and disadvantages of these modification methods, as well as potential future optimization directions, have been outlined. Additionally, novel explorations, such as the construction of O2-type structures, innovative activation methods, and the development of sulfur-based host, are discussed. Finally, we propose future directions to bridge the gap between theoretical and practical capacities, including advanced characterization of oxygen redox dynamics and machine learning-guided evaluation of modifications. This review provides critical insights into advancing high-capacity cathode materials, thus accelerating the commercialization of HM-LLOs.
2025, 41(8): 100086
doi: 10.1016/j.actphy.2025.100086
Abstract:
Two-dimensional covalent organic frameworks (2D COFs) exhibit distinctive characteristics, including tunable topology, an extensive specific surface area, susceptibility to functionalization, and robust stability, making them frequently utilizedin multiphase photocatalytic applications. This article begins with an overview of the synthesis methods for 2D COFs, covering solvothermal, ionothermal, mechanochemical, microwave-assisted, sonochemical, and interfacial synthesis techniques. It provides a concise introduction to various factors influencing photocatalytic performance, such as crystallinity and stability, band structure, charge transfer capability, pore size and specific surface area, and the nature of the light source. Subsequently, the discussion shifts to summarizing and analyzing advancements in the use of 2D COFs as photocatalysts for organic small molecule conversion reactions, particularly in photocatalytic oxidation, reduction, and coupling reactions. Finally, summary and outlook are presented regarding the opportunities and challenges that 2D COFs face in photocatalytic organic transformations. ![]()
Two-dimensional covalent organic frameworks (2D COFs) exhibit distinctive characteristics, including tunable topology, an extensive specific surface area, susceptibility to functionalization, and robust stability, making them frequently utilizedin multiphase photocatalytic applications. This article begins with an overview of the synthesis methods for 2D COFs, covering solvothermal, ionothermal, mechanochemical, microwave-assisted, sonochemical, and interfacial synthesis techniques. It provides a concise introduction to various factors influencing photocatalytic performance, such as crystallinity and stability, band structure, charge transfer capability, pore size and specific surface area, and the nature of the light source. Subsequently, the discussion shifts to summarizing and analyzing advancements in the use of 2D COFs as photocatalysts for organic small molecule conversion reactions, particularly in photocatalytic oxidation, reduction, and coupling reactions. Finally, summary and outlook are presented regarding the opportunities and challenges that 2D COFs face in photocatalytic organic transformations.
2025, 41(8): 100089
doi: 10.1016/j.actphy.2025.100089
Abstract:
Efficient technologies for lithium extraction are progressively pivotal in response to the growing requirement for lithium in new energy applications. However, due to its high energy consumption and possible secondary pollution problems, traditional lithium absorption and recovery technologies, are limited in practical application and development. Capacitive deionization (CDI) demonstrates significant potential for lithium extraction with regard to efficiency, cost-effectiveness, and energy consumption. This review commences with bibliometric analysis to dissect the key research topics of lithium extraction via CDI, and presents a complete synopsis of recent advances in electrode materials for lithium extraction using CDI technology, along with various types of CDI systems that utilize these materials. This study elucidates in detail the main electrode materials used in CDI systems for lithium resource recovery——aqueous lithium ion electrode materials (including LiFePO4, LiMn2O4, LiNi1/3Co1/3Mn1/3O2) and their modification materials (including carbon nanotubes, graphene, MOFs). In addition, this paper discusses the improvement of lithium extraction efficiency through different CDI systems and evaluates the capability of various advanced electrode materials in these systems. The end of the paper emphasizes the application potential of machine learning in the domain of lithium extraction via CDI. The study is anticipated to deliver a strong theoretical basis and practical recommendations for advancing efficient lithium extraction systems that utilize CDI. ![]()
Efficient technologies for lithium extraction are progressively pivotal in response to the growing requirement for lithium in new energy applications. However, due to its high energy consumption and possible secondary pollution problems, traditional lithium absorption and recovery technologies, are limited in practical application and development. Capacitive deionization (CDI) demonstrates significant potential for lithium extraction with regard to efficiency, cost-effectiveness, and energy consumption. This review commences with bibliometric analysis to dissect the key research topics of lithium extraction via CDI, and presents a complete synopsis of recent advances in electrode materials for lithium extraction using CDI technology, along with various types of CDI systems that utilize these materials. This study elucidates in detail the main electrode materials used in CDI systems for lithium resource recovery——aqueous lithium ion electrode materials (including LiFePO4, LiMn2O4, LiNi1/3Co1/3Mn1/3O2) and their modification materials (including carbon nanotubes, graphene, MOFs). In addition, this paper discusses the improvement of lithium extraction efficiency through different CDI systems and evaluates the capability of various advanced electrode materials in these systems. The end of the paper emphasizes the application potential of machine learning in the domain of lithium extraction via CDI. The study is anticipated to deliver a strong theoretical basis and practical recommendations for advancing efficient lithium extraction systems that utilize CDI.
2025, 41(8): 100088
doi: 10.1016/j.actphy.2025.100088
Abstract:
Halide perovskites have attracted widespread attention in the photovoltaic field due to their exception optoelectronic properties and remarkable defect tolerance. The power conversion efficiency of perovskite solar cells has rapidly increased, reaching 26.95%. However, the weak ionic bonding in perovskite materials make them highly sensitive to electric fields, leading to instability under reverse bias, which poses a significant challenge to their commercialization. During operation, partial shading of modules can cause the shaded perovskite sub-cells to become resistive. Consequently, under the influence of other sub-cells, these shaded sub-cells experience reverse bias, resulting in a substantial decline in device performance. Currently, there is no characterization technique available to directly investigate the failure mechanisms of perovskite solar cells under reverse bias. Furthermore, there is no consensus in existing research on the types of ion migration occurring within devices during reverse bias ageing. Since the failure mechanisms of perovskite solar cells under reverse bias remain unclear, effective stability strategies targeting these mechanisms have not been proposed. As a result, reverse bias instability continues to hinder the long-term operational stability of perovskite solar cells. Given these challenges, a comprehensive review of the electrical failure and degradation mechanisms of perovskite solar cells under reverse bias is imperative. This review summarizes the latest research progress on the reverse bias stability of perovskite solar cells, covering key aspects such as the maximum breakdown voltage, electrical evolution, ageing behavior, degradation mechanisms, stability enhancement strategies, and characterization techniques used in stability studies. Finally, this review highlights future research directions for investigating the ageing mechanisms of perovskite solar cells under reverse bias and proposes potential approaches, such as machine learning, to address the reverse bias stability issues of high-efficiency perovskite solar cells, in the hope of paving the way for further improving their reverse bias stability. ![]()
Halide perovskites have attracted widespread attention in the photovoltaic field due to their exception optoelectronic properties and remarkable defect tolerance. The power conversion efficiency of perovskite solar cells has rapidly increased, reaching 26.95%. However, the weak ionic bonding in perovskite materials make them highly sensitive to electric fields, leading to instability under reverse bias, which poses a significant challenge to their commercialization. During operation, partial shading of modules can cause the shaded perovskite sub-cells to become resistive. Consequently, under the influence of other sub-cells, these shaded sub-cells experience reverse bias, resulting in a substantial decline in device performance. Currently, there is no characterization technique available to directly investigate the failure mechanisms of perovskite solar cells under reverse bias. Furthermore, there is no consensus in existing research on the types of ion migration occurring within devices during reverse bias ageing. Since the failure mechanisms of perovskite solar cells under reverse bias remain unclear, effective stability strategies targeting these mechanisms have not been proposed. As a result, reverse bias instability continues to hinder the long-term operational stability of perovskite solar cells. Given these challenges, a comprehensive review of the electrical failure and degradation mechanisms of perovskite solar cells under reverse bias is imperative. This review summarizes the latest research progress on the reverse bias stability of perovskite solar cells, covering key aspects such as the maximum breakdown voltage, electrical evolution, ageing behavior, degradation mechanisms, stability enhancement strategies, and characterization techniques used in stability studies. Finally, this review highlights future research directions for investigating the ageing mechanisms of perovskite solar cells under reverse bias and proposes potential approaches, such as machine learning, to address the reverse bias stability issues of high-efficiency perovskite solar cells, in the hope of paving the way for further improving their reverse bias stability.
2025, 41(8): 100084
doi: 10.1016/j.actphy.2025.100084
Abstract:
Photocatalytic hydrogen (H2) production is a clean energy technology, with great potential for addressing the global energy crisis and related environmental problems. However, single-component photocatalysts often suffer from low efficiency primarily due to fast charge carrier recombination and the tradeoff between light-absorbing capacity and redox capabilities. Constructing heterojunctions provides a promising strategy to overcome these drawbacks, and S-scheme heterojunctions have recently stood out, demonstrating the capability to efficiently facilitate electron/hole separation, while maximizing the redox capability. Among them, polymer-based S-scheme photocatalysts are emerging, though the charge carrier dynamics in inorganic-organic S-scheme heterojunctions remain to be elucidated. Herein, we fabricated an S-scheme heterojunction comprised of the conjugated polymer dibenzothiophene-S, S-dioxide-alt-benzodithiophene (DBTSO-BDTO) and cadmium sulfide (CdS) for photocatalytic H2 production. The S-scheme mechanism was verified using in situ irradiated X-ray photoelectron spectroscopy, and the charge carrier transfer dynamics were analyzed in depth using femtosecond transient absorption spectroscopy, which revealed that a considerable fraction of electrons undergo interfacial charge transfer in the CdS/DBTSO-BDTO composite. Owing to the improved charge separation efficiency and redox capability, the performance of the composite surpassed that of DBTSO-BDTO and CdS, and the H2 evolution rate of the optimized CdS/DBTSO-BDTO material reached 3313 μmol·h−1·g−1, three times that of pure CdS. The findings provide new insights into the electron transfer mechanisms of S-scheme heterojunctions, and can guide the design of polymer-based photocatalysts for solar fuel production. ![]()
Photocatalytic hydrogen (H2) production is a clean energy technology, with great potential for addressing the global energy crisis and related environmental problems. However, single-component photocatalysts often suffer from low efficiency primarily due to fast charge carrier recombination and the tradeoff between light-absorbing capacity and redox capabilities. Constructing heterojunctions provides a promising strategy to overcome these drawbacks, and S-scheme heterojunctions have recently stood out, demonstrating the capability to efficiently facilitate electron/hole separation, while maximizing the redox capability. Among them, polymer-based S-scheme photocatalysts are emerging, though the charge carrier dynamics in inorganic-organic S-scheme heterojunctions remain to be elucidated. Herein, we fabricated an S-scheme heterojunction comprised of the conjugated polymer dibenzothiophene-S, S-dioxide-alt-benzodithiophene (DBTSO-BDTO) and cadmium sulfide (CdS) for photocatalytic H2 production. The S-scheme mechanism was verified using in situ irradiated X-ray photoelectron spectroscopy, and the charge carrier transfer dynamics were analyzed in depth using femtosecond transient absorption spectroscopy, which revealed that a considerable fraction of electrons undergo interfacial charge transfer in the CdS/DBTSO-BDTO composite. Owing to the improved charge separation efficiency and redox capability, the performance of the composite surpassed that of DBTSO-BDTO and CdS, and the H2 evolution rate of the optimized CdS/DBTSO-BDTO material reached 3313 μmol·h−1·g−1, three times that of pure CdS. The findings provide new insights into the electron transfer mechanisms of S-scheme heterojunctions, and can guide the design of polymer-based photocatalysts for solar fuel production.
2025, 41(8): 100087
doi: 10.1016/j.actphy.2025.100087
Abstract:
Raising the charge cut-off voltage of LiCoO2 (LCO) cathodes provides a straightforward approach to increasing the energy density of lithium-ion batteries (LIBs). However, when the charge cut-off voltage exceeds 4.55 V (vs. Li/Li+), the cathode-electrolyte interphase (CEI) becomes unstable, failing to protect the LCO cathode from severe interfacial side reactions and structural instability. These issues accelerate battery degradation and severely hinder the practical application of high-energy-density LIBs. Moreover, ethylene carbonate (EC)-based electrolytes exhibit more pronounced parasitic reactions than EC-free electrolytes under high voltage, further exacerbating performance limitations. Therefore, optimizing the components and structure of the CEI with EC-free electrolytes remains a challenge. In this work, we aim to construct a robust and chemically stable F-/B-containing CEI on the surface of LCO cathodes using an EC-free electrolyte design. By replacing EC with more anti-oxidative propylene carbonate (PC) and fluoroethylene carbonate (FEC) co-solvents, the oxidative stability of the electrolyte is significantly improved. This promotes the formation of LiF within the CEI, thereby enhancing its mechanical strength. Meanwhile, the introduction of the sacrificial film-forming additive lithium bis(oxalato)borate (LiBOB) facilitates the generation of oxalates (Li2C2O4) and B-containing crosslinked polymers (LiBxOy) within the CEI. These components exhibit high electrochemical stability and flexibility, compensating for the limitations of the LiF-rich CEI and further enhancing the overall structural stability of the CEI. This combination results in a rigid-flexible coupling architecture composed of inorganic-rich components (LiF and Li2C2O4) embedded in B-containing crosslinked polymers (LiBxOy), ensuring both mechanical integrity and chemical stability of the CEI. Consequently, this tailored CEI effectively mitigates interfacial layer cracking and regeneration, reducing irreversible structural degradation and interfacial side reactions in high-voltage LCO cathodes. Based on these improvements, the EC-free PC-based electrolyte enables superior performance of LCO cathodes at 4.6 V, achieving 82% capacity retention at 0.5C over 200 cycles. Furthermore, graphite||LCO full cells demonstrate enhanced cycling stability at 4.5 V and enable operation across a wide temperature range (−40 to 80 ℃), highlighting the effectiveness of the rigid-flexible coupling CEI derived from the tailored electrolyte. By moving away from conventional EC-based electrolyte formulas, this work provides new insights into designing high-performance, wide-temperature, and sustainable PC-based electrolytes. ![]()
Raising the charge cut-off voltage of LiCoO2 (LCO) cathodes provides a straightforward approach to increasing the energy density of lithium-ion batteries (LIBs). However, when the charge cut-off voltage exceeds 4.55 V (vs. Li/Li+), the cathode-electrolyte interphase (CEI) becomes unstable, failing to protect the LCO cathode from severe interfacial side reactions and structural instability. These issues accelerate battery degradation and severely hinder the practical application of high-energy-density LIBs. Moreover, ethylene carbonate (EC)-based electrolytes exhibit more pronounced parasitic reactions than EC-free electrolytes under high voltage, further exacerbating performance limitations. Therefore, optimizing the components and structure of the CEI with EC-free electrolytes remains a challenge. In this work, we aim to construct a robust and chemically stable F-/B-containing CEI on the surface of LCO cathodes using an EC-free electrolyte design. By replacing EC with more anti-oxidative propylene carbonate (PC) and fluoroethylene carbonate (FEC) co-solvents, the oxidative stability of the electrolyte is significantly improved. This promotes the formation of LiF within the CEI, thereby enhancing its mechanical strength. Meanwhile, the introduction of the sacrificial film-forming additive lithium bis(oxalato)borate (LiBOB) facilitates the generation of oxalates (Li2C2O4) and B-containing crosslinked polymers (LiBxOy) within the CEI. These components exhibit high electrochemical stability and flexibility, compensating for the limitations of the LiF-rich CEI and further enhancing the overall structural stability of the CEI. This combination results in a rigid-flexible coupling architecture composed of inorganic-rich components (LiF and Li2C2O4) embedded in B-containing crosslinked polymers (LiBxOy), ensuring both mechanical integrity and chemical stability of the CEI. Consequently, this tailored CEI effectively mitigates interfacial layer cracking and regeneration, reducing irreversible structural degradation and interfacial side reactions in high-voltage LCO cathodes. Based on these improvements, the EC-free PC-based electrolyte enables superior performance of LCO cathodes at 4.6 V, achieving 82% capacity retention at 0.5C over 200 cycles. Furthermore, graphite||LCO full cells demonstrate enhanced cycling stability at 4.5 V and enable operation across a wide temperature range (−40 to 80 ℃), highlighting the effectiveness of the rigid-flexible coupling CEI derived from the tailored electrolyte. By moving away from conventional EC-based electrolyte formulas, this work provides new insights into designing high-performance, wide-temperature, and sustainable PC-based electrolytes.
2025, 41(8): 100083
doi: 10.1016/j.actphy.2025.100083
Abstract:
As a highly promising renewable energy technology, the urea oxidation reaction (UOR) not only enables efficient utilization of urea wastewater but also provides an effective alternative for hydrogen production via water electrolysis, thereby reducing the energy consumption of conventional electrolysis. Therefore, the development of UOR catalysts with high catalytic activity and long-term stability is of great significance for advancing clean energy technologies. In this study, a nickel-based selenide catalyst (NiCoMnMo-Se) with coexisting nanoparticles and nanosheets was synthesized using a NaBH4 reduction and selenization strategy. X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-vis) and in situ bode phase plots, revealed that the synergistic effect of Mn and Mo regulated the electronic structure of Ni/Co, enhancing the conductivity of selenide and accelerating charge transfer kinetics, which facilitates the rapid transformation of Ni2+/Co2+ into active Ni3+/Co3+ and significantly reduces the onset potential of NiCoMnMo-Se. During the UOR process, Mo and Se are oxidized to form molybdate and selenate, which subsequently dissolve into the electrolyte. This transformation results in the partial conversion of the original spherical nanoparticle surfaces into nanosheets, thereby exposing more Ni(Co)OOH active sites and significantly enhancing the UOR reaction. Additionally, the introduction of Mn stabilizes the active sites, thereby improving the overall stability of the catalyst. As anticipated, the synthesized NiCoMnMo-Se catalyst demonstrates outstanding electrocatalytic performance and stability in the UOR process, achieving a current density of 50 mA·cm−2 at a potential of only 1.38 V vs. RHE (reversible hydrogen electrode), with a voltage increase of only 3.0% after 50 h of operation at a 50 mA·cm−2. When NiCoMnMo-Se and commercial Pt/C were assembled into a dual-electrode system for alkaline urea electrolysis, it only requires 1.59 V vs. RHE to achieve a current density of 50 mA·cm−2. This paper designs an efficient and stable Ni-based selenide catalyst, which is expected to promote the further development of selenides in relevant energy technologies. ![]()
As a highly promising renewable energy technology, the urea oxidation reaction (UOR) not only enables efficient utilization of urea wastewater but also provides an effective alternative for hydrogen production via water electrolysis, thereby reducing the energy consumption of conventional electrolysis. Therefore, the development of UOR catalysts with high catalytic activity and long-term stability is of great significance for advancing clean energy technologies. In this study, a nickel-based selenide catalyst (NiCoMnMo-Se) with coexisting nanoparticles and nanosheets was synthesized using a NaBH4 reduction and selenization strategy. X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-vis) and in situ bode phase plots, revealed that the synergistic effect of Mn and Mo regulated the electronic structure of Ni/Co, enhancing the conductivity of selenide and accelerating charge transfer kinetics, which facilitates the rapid transformation of Ni2+/Co2+ into active Ni3+/Co3+ and significantly reduces the onset potential of NiCoMnMo-Se. During the UOR process, Mo and Se are oxidized to form molybdate and selenate, which subsequently dissolve into the electrolyte. This transformation results in the partial conversion of the original spherical nanoparticle surfaces into nanosheets, thereby exposing more Ni(Co)OOH active sites and significantly enhancing the UOR reaction. Additionally, the introduction of Mn stabilizes the active sites, thereby improving the overall stability of the catalyst. As anticipated, the synthesized NiCoMnMo-Se catalyst demonstrates outstanding electrocatalytic performance and stability in the UOR process, achieving a current density of 50 mA·cm−2 at a potential of only 1.38 V vs. RHE (reversible hydrogen electrode), with a voltage increase of only 3.0% after 50 h of operation at a 50 mA·cm−2. When NiCoMnMo-Se and commercial Pt/C were assembled into a dual-electrode system for alkaline urea electrolysis, it only requires 1.59 V vs. RHE to achieve a current density of 50 mA·cm−2. This paper designs an efficient and stable Ni-based selenide catalyst, which is expected to promote the further development of selenides in relevant energy technologies.
2025, 41(8): 100095
doi: 10.1016/j.actphy.2025.100095
Abstract:
Designing heterojunctions based on carbon nitride offers a promising pathway for enhancing photocatalytic efficiency. This study develops an all-organic S-scheme metal-free heterojunction uniquely composed of carbon nitride nanosheets (GCNNS) and a donor-acceptor conjugated polymer, poly p-aminobenzylidene-so-aniline (PASO), synthesized through a simple yet effective ball-milling technique. This heterojunction demonstrates excellent photocatalytic efficiency for hydrogen (H2) evolution. The optimized GCNNS/PASO-10 sample attains an H2 evolution rate of 10.12 mmol·g−1·h−1, which is about 5.9 times and 19.5 times greater than those of pure GCNNS and PASO, respectively. This improvement is due to the unique interfacial bonding, increased visible-light absorption, and efficient charge carrier separation facilitated by a strong internal electric field within the S-scheme. Theoretical calculations and characterization reveal that this heterojunction's S-scheme mechanism optimally aligns energy bands and promotes spatial charge separation, driving superior photocatalytic activity. This work presents the unique advantage of all-organic materials for heterojunction construction and provides insights into designing advanced S-scheme systems for sustainable energy conversion. ![]()
Designing heterojunctions based on carbon nitride offers a promising pathway for enhancing photocatalytic efficiency. This study develops an all-organic S-scheme metal-free heterojunction uniquely composed of carbon nitride nanosheets (GCNNS) and a donor-acceptor conjugated polymer, poly p-aminobenzylidene-so-aniline (PASO), synthesized through a simple yet effective ball-milling technique. This heterojunction demonstrates excellent photocatalytic efficiency for hydrogen (H2) evolution. The optimized GCNNS/PASO-10 sample attains an H2 evolution rate of 10.12 mmol·g−1·h−1, which is about 5.9 times and 19.5 times greater than those of pure GCNNS and PASO, respectively. This improvement is due to the unique interfacial bonding, increased visible-light absorption, and efficient charge carrier separation facilitated by a strong internal electric field within the S-scheme. Theoretical calculations and characterization reveal that this heterojunction's S-scheme mechanism optimally aligns energy bands and promotes spatial charge separation, driving superior photocatalytic activity. This work presents the unique advantage of all-organic materials for heterojunction construction and provides insights into designing advanced S-scheme systems for sustainable energy conversion.
2025, 41(8): 100093
doi: 10.1016/j.actphy.2025.100093
Abstract:
Green photocatalytic synthesis of hydrogen peroxide (H2O2) represents a promising alternative to the energy-intensive anthraquinone process, yet it is hindered by rapid carrier recombination and insufficient redox capacity in sacrificial-agent-free systems. This work reports a melamine foam (MF)-supported sulfur (S)-doped carbon nitride (SCN)/S vacancy-modified Cd0.5Zn0.5In2S4 (CZIS) S-scheme heterojunction (CZIS/SCN/MF) via an in situ chemical bath-hydrothermal method for sacrificial-agent-free H2O2 photosynthesis. The S-scheme charge transfer mechanism was confirmed by in situ irradiated X-ray photoelectron spectroscopy, free-radical trapping electron paramagnetic resonance, femtosecond transient absorption spectra and theoretical calculations. Specifically, the sulfur doping could modulate the local charge distribution of the carbon nitride framework to reinforce the interfacial built-in electric field for the CZIS/SCN S-scheme heterojunction. Meanwhile, the calcination-induced S-vacancies in CZIS could serve as photoelectron traps, promoting charge separation, and reserving photoinduced holes for H2O oxidation, thereby achieving sacrificial-agent-free H2O2 synthesis. Coupled with the photothermal effect of MF's three-dimensional porous framework, the CZIS/SCN/MF catalyst with optimized S-doping density and SCN dosage delivers an H2O2 production rate of 3.46 mmol·g−1·h−1 in pure water, surpassing most of the sacrificial-agent-free systems. This study proposes a novel strategy for synergistic interfacial charge regulation and energy conversion enhancement in sacrificial-agent-free photocatalytic systems. ![]()
Green photocatalytic synthesis of hydrogen peroxide (H2O2) represents a promising alternative to the energy-intensive anthraquinone process, yet it is hindered by rapid carrier recombination and insufficient redox capacity in sacrificial-agent-free systems. This work reports a melamine foam (MF)-supported sulfur (S)-doped carbon nitride (SCN)/S vacancy-modified Cd0.5Zn0.5In2S4 (CZIS) S-scheme heterojunction (CZIS/SCN/MF) via an in situ chemical bath-hydrothermal method for sacrificial-agent-free H2O2 photosynthesis. The S-scheme charge transfer mechanism was confirmed by in situ irradiated X-ray photoelectron spectroscopy, free-radical trapping electron paramagnetic resonance, femtosecond transient absorption spectra and theoretical calculations. Specifically, the sulfur doping could modulate the local charge distribution of the carbon nitride framework to reinforce the interfacial built-in electric field for the CZIS/SCN S-scheme heterojunction. Meanwhile, the calcination-induced S-vacancies in CZIS could serve as photoelectron traps, promoting charge separation, and reserving photoinduced holes for H2O oxidation, thereby achieving sacrificial-agent-free H2O2 synthesis. Coupled with the photothermal effect of MF's three-dimensional porous framework, the CZIS/SCN/MF catalyst with optimized S-doping density and SCN dosage delivers an H2O2 production rate of 3.46 mmol·g−1·h−1 in pure water, surpassing most of the sacrificial-agent-free systems. This study proposes a novel strategy for synergistic interfacial charge regulation and energy conversion enhancement in sacrificial-agent-free photocatalytic systems.
