2023 Vol. 8, No. 4

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Perspective
A leap by the rise of solid-state electrolytes for Li-air batteries
Kecheng Pan, Minghui Li, Weicheng Wang, Shuochao Xing, Yaying Dou, Shasha Gao, Zhang Zhang, Zhen Zhou
2023, 8(4): 939-944. doi: 10.1016/j.gee.2023.02.010
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Li-air batteries have attracted extensive attention because of their ultrahigh theoretical energy density. However, the potential safety hazard of flammable organic liquid electrolytes hinders their practical applications. Replacing liquid electrolytes with solidstate electrolytes (SSEs) is expected to fundamentally overcome the safety issues. In this work, we focus on the development and challenge of solid-stateLi-air batteries (SSLABs). The rise of different types of SSEs, interfacial compatibility and verifiability in SSLABs are presented. The corresponding strategies and prospects of SSLABs are also proposed. In particular, combining machine learning method with experiment and in situ (or operando) techniques is imperative to accelerate the development of SSLABs.
Commentary
Process reconfiguration and intensification: An emerging opportunity enabling efficient carbon capture and low-cost blue hydrogen production
Dongke Zhang
2023, 8(4): 945-947. doi: 10.1016/j.gee.2023.03.004
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Low-carbon hydrogen can play a significant role in decarbonizing the world. Hydrogen is currently mainly produced from fossil sources, requiring additional CO2 capture to decarbonize, which energy intense and costly. In a recent Green Energy & Environment paper, Cheng and Di et al. proposed a novel integration process referred to as SECLRHC to generate high-purity H2 by in-situ separation of H2 and CO without using any additional separation unit. Theoretically, the proposed process can essentially achieve the separation of C and H in gaseous fuel via a reconfigured reaction process, and thus attaining high-purity hydrogen of ~99%, as well as good carbon and hydrogen utilization rates and economic feasibility. It displays an optimistic prospect that industrial decarbonization is not necessarily expensive, as long as a suitable CCS measure can be integrated into the industrial manufacturing process.
Review articles
Ammonia borane-enabled hydrogen transfer processes: Insights into catalytic strategies and mechanisms
Wenfeng Zhao, Hu Li, Heng Zhang, Song Yang, Anders Riisager
2023, 8(4): 948-971. doi: 10.1016/j.gee.2022.03.011
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Transfer hydrogenation (TH) with in situ generated hydrogen donor is of great importance in reduction reactions, and an alternative strategy to traditional hydrogenation processes involving pressurized molecular hydrogen. Ammonia borane (NH3BH3, AB) is a promising material of hydrogen storage, and it has attracted much attention in reductive organic transformations owing to its high activity, good atom economy, non-toxicity, sustainability, and ease of transport and storage. This review focuses on summarizing the recent progress of AB-mediated TH reactions of diverse substrates including nitro compounds, nitriles, imines, alkenes, alkynes, carbonyl compounds (ketones and aldehydes), carbon dioxide, and N- and O-heterocycles. Syntheses protocols (metal-containing and metal-free), the effect of reaction parameters, product distribution, and variation of reactivity are surveyed, and the mechanism of each reaction involving the action mode of AB as well as structure-activity relationships is discussed in detail. Finally, perspectives are presented to highlight the challenges and opportunities for AB-enabled TH reactions of unsaturated compounds.
A survey of hybrid energy devices based on supercapacitors
Dan Gao, Zhiling Luo, Changhong Liu, Shoushan Fan
2023, 8(4): 972-988. doi: 10.1016/j.gee.2022.02.002
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Developing multifunctional energy storage systems with high specific energy, high specific power and long cycling life has been the one of the most important research directions. Compared to batteries and traditional capacitors, supercapacitors possess more balanced performance with both high specific power and long cycle-life. Nevertheless, regular supercapacitors can only achieve energy storage without harvesting energy and the energy density is still not very high compared to batteries. Therefore, combining high specific energy and high specific power, long cycle-life and even fast self-charging into one cell has been a promising direction for future energy storage devices. The multifunctional hybrid supercapacitors like asymmetric supercapacitors, batteries/supercapacitors hybrid devices and self-charging hybrid supercapacitors have been widely studied recently. Carbon based electrodes are common materials used in all kinds of energy storage devices due to their fabulous electrical and mechanical properties. In this survey, the research progress of all kinds of hybrid supercapacitors using multiple effects and their working mechanisms are briefly reviewed. And their advantages and disadvantages are discussed. The hybrid supercapacitors have great application potential for portable electronics, wearable devices and implantable devices in the future.
Strategic comparison of membrane-assisted and membrane-less water electrolyzers and their potential application in direct seawater splitting (DSS)
Abdul Malek, Xu Lu, Paul R. Shearing, Dan J.L. Brett, Guanjie He
2023, 8(4): 989-1005. doi: 10.1016/j.gee.2022.06.006
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Electrocatalytic splitting of water by means of renewable energy as the electricity supply is one of the most promising methods for storing green renewable energy as hydrogen. Although two-thirds of the earth's surface is covered with water, there is inadequacy of freshwater in most parts of the world. Hence, splitting seawater instead of freshwater could be a truly sustainable alternative. However, direct seawater splitting faces challenges because of the complex composition of seawater. The composition, and hence, the local chemistry of seawater may vary depending on its origin, and in most cases, tracking of the side reactions and standardizing and customizing the catalytic process will be an extra challenge. The corrosion of catalysts and competitive side reactions due to the presence of various inorganic and organic pollutants create challenges for developing stable electro-catalysts. Hence, seawater splitting generally involves a two-step process, i.e., purification of seawater using reverse osmosis and then subsequent fresh water splitting. However, this demands two separate chambers and larger space, and increases complexity of the reactor design. Recently, there have been efforts to directly split seawater without the reverse osmosis step. Herein, we represent the most recent innovative approaches to avoid the two-step process, and compare the potential application of membrane-assisted and membrane-less electrolyzers in direct seawater splitting (DSS). We particularly discuss the device engineering, and propose a novel electrolyzer design strategies for concentration gradient based membrane-less microfluidic electrolyzer.
An in-depth understanding of improvement strategies and corresponding characterizations towards Zn anode in aqueous Zn-ions batteries
Yuzhu Chu, Lingxiao Ren, Zhenglin Hu, Chengde Huang, Jiayan Luo
2023, 8(4): 1006-1042. doi: 10.1016/j.gee.2022.04.008
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Combining the unique advantages of aqueous electrolytes and metallic Zn anode, rechargeable aqueous Zn-ion batteries (ZIBs) are of great promise for large-scale energy storage applications due to their inherent high safety, low cost, and environmental friendliness. As the essential component of ZIBs, Zn metal anode suffers from severe dendrite formation and inevitable side reactions (e.g. corrosion and hydrogen evolution) in aqueous electrolytes, which leads to low Coulombic efficiency and inferior cycling stability, impeding their large-scale applications. To be compatible with satisfactory aqueous ZIBs, Zn anode has been modified from various perspectives and focus areas. Herein, based on their intrinsic characteristics, we review the related improvement strategies for Zn anode, including interphase, substrate, and bulk design, so as to achieve an in-depth understanding of Zn anode optimization. Furthermore, the timely summary of characterization methods for Zn anodes are also performed for the first time, from both thermodynamic and kinetics perspectives, which is particularly helpful for beginners to understand the complicated characterizations and employ suitable methods. Finally, certain noteworthy points are put forward for subsequent investigation of aqueous ZIBs. It is expected that this review will enlighten researchers to explore more efficient optimization strategies for Zn anode in aqueous electrolytes.
Bimetallic catalysts as electrocatalytic cathode materials for the oxygen reduction reaction in microbial fuel cell: A review
Ke Zhao, Yuanxiang Shu, Fengxiang Li, Guosong Peng
2023, 8(4): 1043-1070. doi: 10.1016/j.gee.2022.10.007
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Microbial fuel cell (MFC) is one synchronous power generation device for wastewater treatment that takes into account environmental and energy issues, exhibiting promising potential. Sluggish oxygen reduction reaction (ORR) kinetics on the cathode remains by far the most critical bottleneck hindering the practical application of MFC. An ideal cathode catalyst should possess excellent ORR activity, stability, and cost-effectiveness, experiments have demonstrated that bimetallic catalysts are one of the most promising ORR catalysts currently. Based on this, this review mainly analyzes the reaction mechanism (ORR mechanisms, synergistic effects), advantages (combined with characterization technologies), and typical synthesis methods of bimetallic catalysts, focusing on the application effects of early Pt-M (M = Fe, Co, and Ni) alloys to bifunctional catalysts in MFC, pointing out that the main existing challenges remain economic analysis, long-term durability and large-scale application, and looking forward to this. At last, the research trend of bimetallic catalysts suitable for MFC is evaluated, and it is considered that the development and research of metal-organic framework (MOF)-based bimetallic catalysts are still worth focusing on in the future, intending to provide a reference for MFC to achieve energy-efficient wastewater treatment.
Research papers
Nano silica aerogel-induced formation of an organic/alloy biphasic interfacial layer enables construction of stable high-energy lithium metal batteries
Chengwei Ma, Xinyu Zhang, Chengcai Liu, Yuanxing Zhang, Yuanshen Wang, Ling Liu, Zhikun Zhao, Borong Wu, Daobin Mu
2023, 8(4): 1071-1080. doi: 10.1016/j.gee.2021.12.006
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Lithium metal batteries represent promising candidates for high-energy-density batteries, however, many challenges must still be overcome, e.g., interface instability and dendrite growth. In this work, nano silica aerogel was employed to generate a hybrid film with high lithium ion conductivity (0.6 mS cm-1 at room temperature) via an in situ crosslinking reaction. TOF-SIMS profile analysis has revealed conversion mechanism of hybrid film to Li–Si alloy/LiF biphasic interface layer, suggesting that the Li–Si alloy and LiF-rich interface layer promoted rapid Li+ transport and shielded the Li anodes from corrosive reactions with electrolyte-derived products. When coupled with nickel-cobalt-manganese-based cathodes, the batteries achieve outstanding capacity retention over 1000 cycles at 1 C. Additionally the developed film coated on Li enabled high coulombic efficiency (99.5%) after long-term cycling when coupled with S cathodes. Overall, the results presented herein confirm an effective strategy for the development of high-energy batteries.
Construction of truncated-octahedral LiMn2O4 for battery-like electrochemical lithium recovery from brine
Guolang Zhou, Linlin Chen, Xiaowei Li, Guiling Luo, Zhendong Yu, Jingzhou Yin, Lei Fan, Yanhong Chao, Lei Jiang, Wenshuai Zhu
2023, 8(4): 1081-1090. doi: 10.1016/j.gee.2021.12.002
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The extraction of lithium from salt lakes or seawater has attracted worldwide attention because of the explosive growth of global demand for lithium products. The LiMn2O4-based electrochemical lithium recovery system is one of the strongest candidates for commercial application due to its high inserted capacity and low energy consumption. However, the surface orientation of LiMn2O4 that facilitates Li diffusion happens to be prone to manganese dissolution making it a great challenge to obtain high lithium inserted capacity and long life simultaneously. Herein, we address this problem by designing a truncated octahedral LiMn2O4 (Tr-oh LMO) in which the dominant (111) facets minimize Mn dissolution while a small portion of (100) facets facilitate the Li diffusion. Thus, this Tr-oh LMO-based electrochemical lithium recovery system shows excellent Li recovery performance with high inserted capacity (20.25 mg g-1 per cycle) in simulated brine. In addition, the dissolution rate of manganese per 30 cycles is only 0.44% and the capacity maintained 85% of the initial after 30 cycles. These promising findings accelerate the practical application of LiMn2O4 in electrochemical lithium recovery.
All-cellulose-based quasi-solid-state supercapacitor with nitrogen and boron dual-doped carbon electrodes exhibiting high energy density and excellent cyclic stability
Kaixuan Li, Ping Li, Zining Sun, Jing Shi, Minghua Huang, Jingwei Chen, Shuai Liu, Zhicheng Shi, Huanlei Wang
2023, 8(4): 1091-1101. doi: 10.1016/j.gee.2022.01.002
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The key to construct high-energy supercapacitors is to maximize the capacitance of electrode and the voltage of the device. Realizing this purpose by utilizing sustainable and low-cost resources is still a big challenge. Herein, N, B co-doped carbon nanosheets are obtained through the proposed dual-template assisted approach by using methyl cellulose as the precursor. Due to the synergistic effects form the high surface area with the hierarchical porous structure, N/B dual doping, and a high degree of graphitization, the resultant carbon electrode exhibits a high capacitance of 572 F g-1 at 0.5 A g-1 and retains 281 F g-1 at 50 A g-1 in an acidic electrolyte. Furthermore, the symmetric device assembled using bacterial cellulose-based gel polymer electrolyte can deliver high energy density of 43 W h kg-1 and excellent cyclability with 97.8% capacity retention after 20 000 cycles in “water in salt” electrolyte. This work successfully realizes the fabrication of high-performance all-cellulose-based quasi-solid-state supercapacitors, which brings a cost-effective insight into jointly designing electrodes and electrolytes for supporting highly efficient energy storage.
Robust photo-assisted removal of NO at room temperature: Experimental and density functional theory calculation with optical carrier
Yanqin Li, Junqi Tian, Zhisong Liu, Zhongqi Liu, Dong Dong, Fu Wang, Wei Wang, Minmin Liu, Jianming Dan, Yongsheng Li, Feng Yu, Bin Dai, Yunbo Yu
2023, 8(4): 1102-1116. doi: 10.1016/j.gee.2022.01.004
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Photo-assisted SCR (PSCR) offers a potential solution for removal of NO at room temperature. MnTiOx as PSCR catalyst exhibits superior performance with NO removal of 100% at the room temperature. Electron paramagnetic resonance (EPR) analysis revealed the presence of numerous oxygen vacancies on MnTiOx. Optical carrier density functional theory (DFT) calculations showed that the three-dimensional orbital hybridization of Mn and Ti is significantly enhanced under light irradiation. The MnTiOx catalyst exhibited excellent electron–hole separation ability, which can adsorbe NH3 and dissociate to form NH2 fragments and H atoms. In-situ diffuse reflectance infrared fourier-transform spectroscopy (DRIFTS) indicated that the optical carrier enhanced NH3 adsorption on MnTiOx, which makes it possess excellent PSCR activity. This work provided an additional strategy to NO removal with PSCR catalysts and showed potential for use in photocatalysis.
Solid-state Al-air battery with an ethanol gel electrolyte
Yifei Wang, Wending Pan, Kee Wah Leong, Shijing Luo, Xiaolong Zhao, Dennis Y.C. Leung
2023, 8(4): 1117-1127. doi: 10.1016/j.gee.2021.05.011
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Hydrogel electrolyte is especially suitable for solid-state Al-air batteries targeted for various portable applications, which may, however, lead to continuous Al corrosion during battery standby. To tackle this issue, an ethanol gel electrolyte is developed for Al-air battery for the first time in this work, by using KOH as solute and polyethylene oxide as gelling agent. The ethanol gel is found to effectively inhibit Al corrosion compared with the water gel counterpart, leading to stable Al storage. When assembled into an Al-air battery, the ethanol gel electrolyte achieves a much improved discharge lifetime and specific capacity, which are 5.3 and 4.1 times of the water gel electrolyte at 0.1 mA cm-2, respectively. By studying the gel properties, it is found that a lower ethanol purity can improve the battery power output, but at the price of decreased discharge efficiency. On the contrary, a higher polymer concentration will decrease the power output, but can bring extra benefit to the discharge efficiency. As for the gel thickness, a moderate value of 1 mm is preferred to balance the power output and energy efficiency. Finally, to cater the increasing market of flexible electronics, a flexible Al-air battery is developed by impregnating the ethanol gel into a paper substrate, which can function normally even under serious deformation or damage.
Electron-deficient Cu site catalyzed acetylene hydrochlorination
Bolin Wang, Chunxiao Jin, Shujuan Shao, Yuxue Yue, Yuteng Zhang, Saisai Wang, Renqin Chang, Haifeng Zhang, Jia Zhao, Xiaonian Li
2023, 8(4): 1128-1140. doi: 10.1016/j.gee.2022.01.005
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Rational design of catalytic sites to activate the C≡C bond is of paramount importance to advance acetylene hydrochlorination. Herein, Cu sites with electron-rich and electron-deficient states were constructed by controlling the impregnation solutions. The π electrons flowing from acetylene to Cu site are facilitated over the electron-deficient Cu sites, achieving high activation of C≡C bond. The contradiction between the increased activation of acetylene required for enhanced catalytic activity and the resistance of Cu site to reduction by acetylene required for maintaining catalytic stability can be balanced by establishing strong interactions of Cu site with pyrrolic-N species. The catalytic activity displays a volcano shape scaling relationship as a function of Cu particle size. Tribasic copper chloride is concomitantly generated with the construction of electron-deficient Cu sites. The H–Cl bond of HCl can be activated over the tribasic copper chloride, accelerating the surface reaction of vinyl chloride production. This strategy of inducing electron deficiency provides new insight into the rational design of catalysts for the synthesis of vinyl chloride with a high catalytic performance.
Regulating the coordination environment of Ru single-atom catalysts and unravelling the reaction path of acetylene hydrochlorination
Yang Yang, Chaoyue Zhao, Xianliang Qiao, Qingxin Guan, Wei Li
2023, 8(4): 1141-1153. doi: 10.1016/j.gee.2022.01.006
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In this work, DFT calculations were used firstly to simulate the nitrogen coordinated metal single-atom catalysts (M-Nx SACs, M = Hg, Cu, Au, and Ru) to predict their catalytic activities in acetylene hydrochlorination. The DFT results showed that Ru-Nx SACs had the best catalytic performance among the four catalysts, and Ru-Nx SACs could effectively inhibit the reduction of ruthenium cation. To verify the DFT results, Ru-Nx SACs were fabricated by pyrolyzing MOFs in-situ spatially confined metal precursors. The N coordination environment could be controlled by changing the pyrolysis temperature. Catalytic performance tests indicated that low N coordination number (Ru–N2, Ru–N3) exhibited excellent catalytic activity and stability compared to RuCl3 catalyst. DFT calculations further revealed that Ru–N2 and Ru–N3 had a tendency to activate HCl at the first step of reaction, whereas Ru–N4 tended to activate C2H2. These findings will serve as a reference for the design and control of metal active sites.
Smart heat isolator with hollow multishelled structures
Kun Wang, Lekai Xu, Jiao Wang, Shaojun Zhang, Yanlei Wang, Nailiang Yang, Jiang Du, Dan Wang
2023, 8(4): 1154-1160. doi: 10.1016/j.gee.2022.01.003
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Safe, green and efficient industrial production has always been the pursuit of the chemical industry. Since thermal energy is the driving force for most of chemical reactions, an ideal reaction tank would have the capacity to automatically regulate heat conduction rate. In detail, this reaction tank should endow an ability that resists the heat loss when the reaction temperature is lower than the target, while accelerating the heat dissipation when the system is overheated. In this case, this smart reactor can not only minimize energy consumption but also reduce safety risks. Hollow structures are known to reduce heat conductivity. Particularly, the hollow structure with multishells can provide more interfaces and thus further inhibit heat transmission, which would be more favorable for heat isolation. Step forward, by coupling HoMSs with temperature-sensitive polymer, a smart heat isolation material has been fabricated in this work. It performs as a good heat isolator at a relatively lower temperature. A heat insulation effect of 6.5 ℃ can be achieved for the TSPU/3S–TiO2 HoMSs with a thickness of 1 mm under the temperature field of 50 ℃. The thermal conductivity of composite material would be raised under overheating conditions. Furthermore, this composite displays an unusual two-stage phase transformation during heating. Benefiting from the unique multishelled structure, energy is found to be gradually guided into the hollow structure and stored inside. This localized heat accumulation enables the composite to be a potential coating material for intelligent thermal-regulator and site-defined micro-reactor.
Oxidation of benzene to phenol with N2O over a hierarchical Fe/ZSM-5 catalyst
Cui Ouyang, Jianwei Li, Yaqi Qu, Song Hong, Songbo He
2023, 8(4): 1161-1173. doi: 10.1016/j.gee.2022.01.007
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Catalytic oxidation of benzene with N2O to phenol over the hierarchical and microporous Fe/ZSM-5-based catalysts in a continuous fixed-bed reactor was investigated. The spent catalyst was in-situ regenerated by an oxidative treatment using N2O and in total 10 reaction-regeneration cycles were performed. A 100% N2O conversion, 93.3% phenol selectivity, and high initial phenol formation rate of 16.49 ± 0.06 mmolphenol gcatalyst-1 h-1 at time on stream (TOS) of 5 min, and a good phenol productivity of 147.06 mmolphenol gcatalyst-1 during catalyst life-time of 1800 min were obtained on a fresh hierarchical Fe/ZSM-5-Hi2.8 catalyst. With the reaction-regeneration cycle, N2O conversion is fully recovered within TOS of 3 h, moreover, the phenol productivity was decreased ca. 2.2 ± 0.8% after each cycle, leading to a total phenol productivity of ca. 0.44 tonphenol kgcatalyst-1 estimated for 300 cycles. Catalyst characterizations imply that the coke is rapidly deposited on catalyst surface in the initial TOS of 3 h (0.28 mgc gcatalyst-1 min-1) and gradually becomes graphitic during the TOS of 30 h with a slow formation rate of 0.06 mgc gcatalyst-1 min-1. Among others (e.g., the decrease of textural property and acidity), the nearly complete coverage of the active Fe-O-Al sites by coke accounts for the main catalyst deactivation. Besides these reversible deactivation characteristics related to coking, the irreversible catalyst deactivation is also observed with the reaction-regeneration cycle. The latter is reflected by a further decreased amount of the active Fe-O-Al sites, which agglomerate on catalyst surface with the cycle, likely associated with the hard coke residue that is not completely removed by the regeneration.
Intercalation assisted liquid phase production of disulfide zirconium nanosheets for efficient electrocatalytic dinitrogen reduction to ammonia
Yangshuo Li, Huiyong Wang, Bing Chang, Yingying Guo, Zhiyong Li, Shamraiz Hussain Talib, Zhansheng Lu, Jianji Wang
2023, 8(4): 1174-1184. doi: 10.1016/j.gee.2022.01.009
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Disulfide zirconium (ZrS2) is a two-dimensional (2D) transition metal disulfide and has given rise to extensive attention because of its distinctive electronic structure and properties. However, mass production of high quality of ZrS2 nanosheets to realize their practical application remains a challenge. Here, we have successfully exfoliated the bulk ZrS2 powder with the thickness of micron into single and few-layer nanosheets through liquid-phase exfoliation in N-methylpyrrolidone (NMP) assisted via aliphatic amines as intercalators. It is found that the exfoliation yield is as high as 27.3%, which is the record value for the exfoliation of ZrS2 nanosheets from bulk ZrS2 powder, and 77.1% of ZrS2 nanosheets are 2–3 layers. The molecular geometric size and aliphatic amine basicity have important impact on the exfoliation. Furthermore, the ZrS2 nanosheets have been used as catalyst in the electrocatalytic dinitrogen reduction with the NH3 yield of 57.75 μg h-1 mgcat.-1, which is twice that by ZrS2 nanofibers reported in literature and three times that by the bulk ZrS2 powder. Therefore, the liquid phase exfoliation strategy reported here has great potential in mass production of ZrS2 nanosheets for high activity electrocatalysis.
Vacancy engineering of oxidized Nb2CTx MXenes for a biased nitrogen fixation
Mengzhao Zhang, Hanqing Yin, Fuhao Jin, Jingquan Liu, Xuqiang Ji, Aijun Du, Wenrong Yang, Zhen Liu
2023, 8(4): 1185-1194. doi: 10.1016/j.gee.2022.01.010
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The artificial nitrogen (N2) reduction reaction (NRR) via electrocatalysis is a newly developed methodology to produce ammonia (NH3) at ambient conditions, but faces the challenges in N2 activation and poor reaction selectivity. Herein, Nb-based MXenes are developed to remarkably enhance the NRR activity through the engineering of the stretched 3D structure and oxygen vacancies (VO). The theoretical studies indicate that N2 could be initially adsorbed on VO with an end-on configuration, and the potential determining step might be the first hydrogenation step. The catalysts achieve an NH3 production rate of 29.1 μg h-1 mgcat-1 and excellent Faradic efficiency of 11.5%, surpassing other Nb-based catalysts. The selectivity of NRR is assigned to the unique structure of the catalysts, including (1) the layered graphitic structure for fast electron transfer and active site distribution, (2) the reactive VO for N2 adsorption and activation, and (3) the expanded interlayer space for mass transfer.
Tuning composite solid-state electrolyte interface to improve the electrochemical performance of lithium-oxygen battery
Hao Ouyang, Shan Min, Jin Yi, Xiaoyu Liu, Fanghua Ning, Jiaqian Qin, Yong Jiang, Bing Zhao, Jiujun Zhang
2023, 8(4): 1195-1204. doi: 10.1016/j.gee.2022.01.014
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Thin and flexible composite solid-state electrolyte (SSE) is considered to be a prospective candidate for lithium-oxygen (Li-O2) batteries with the aim to address the problems of unsatisfied safety, terrible durability as well as inferior electrochemical performance. Herein, in order to improve the safety and durability, a succinonitrile (SN) modified composite SSE is proposed. In this SSE, SN is introduced for eliminating the boundary between ceramic particles, increasing the amorphous region of polymer and ensuring fast ionic transport. Subsequently, the symmetric battery based on the proposed SSE achieves a long cycle life of 3000 h. Moreover, the elaborate cathode interface through the SN participation effectively reduces the barriers to the combination between lithium ions and electrons, facilitating the corresponding electrochemical reactions. As a result, the solid-state Li-O2 battery based on this SSE and tuned cathode interface achieves improved electrochemical performance including large specific capacity over 12,000 mAh g-1, enhanced rate capacity as well as stable cycle life of 54 cycles at room temperature. This ingenious design provides a new orientation for the evolution of solid-state Li-O2 batteries.
Pd nanoparticles embedded in N-Enriched MOF-Derived architectures for efficient oxygen reduction reaction in alkaline media
Daqiang Yan, Lin Zhang, Lei Shen, Runyu Hu, Weiping Xiao, Xiaofei Yang
2023, 8(4): 1205-1215. doi: 10.1016/j.gee.2022.01.011
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Developing high efficient Pd-based electrocatalysts for oxygen reduction reaction (ORR) is still challenging for alkaline membrane fuel cell, since the strong oxygen adsorption energy and easy agglomerative intrinsic properties. In order to simultaneously solve these problems, Pd/Co3O4–N–C multidimensional materials with porous structures is designed as the ORR catalysts. In details, the ZIF-67 with polyhedral structure was firstly synthesized and then annealed at high-temperature to prepare the N-doped Co3O4 carbon-based material, which was used to homogeneously confine Pd nanoparticles and obtained the Pd/Co3O4–N–C series catalysts. The formation of Co–N and C–N bond could provide efficient active sites for ORR. Simultaneously, the strong electronic interaction in the interface between the Pd and N-doped Co3O4 could disperse and avoid the agglomeration of Pd nanoparticles and ensure the exposure of active sites, which is crucial to lower the energy barrier toward ORR and substantially enhance the ORR kinetics. Hence, the Pd/Co3O4–N–C nanocompounds exhibited excellent ORR catalytic performance, ideal Pd mass activity, and durability in 0.1 mol L-1 KOH solution compared with Co3O4–N–C and Pd/C. The scalable synthesis method, relatively low cost, and excellent electrochemical ORR performance indicated that the obtained Pd/Co3O4–N–C electrocatalyst had the potential for application on fuel cells.
Breaking the temperature limit of hydrothermal carbonization of lignocellulosic biomass by decoupling temperature and pressure
Shijie Yu, Xiaoxiao Yang, Qinghai Li, Yanguo Zhang, Hui Zhou
2023, 8(4): 1216-1227. doi: 10.1016/j.gee.2023.01.001
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Hydrothermal carbonization (HTC) of lignocellulosic biomass is a promising technology for the production of carbon materials with negative carbon emissions. However, the high reaction temperature and energy consumption have limited the development of HTC technology. In conventional batch reactors, the temperature and pressure are typically coupled at saturated states. In this study, a decoupled temperature and pressure hydrothermal (DTPH) reaction system was developed to decrease the temperature of the HTC reaction of lignocellulosic biomass (rice straw and poplar leaves). The properties of hydrochars were analyzed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric analyzer (TGA), etc. to propose the reaction mechanism. The results showed that the HTC reaction of lignocellulosic biomass could be realized at a low temperature of 200 ℃ in the DTPH process, breaking the temperature limit (230 ℃) in the conventional process. The DTPH method could break the barrier of the crystalline structure of cellulose in the lignocellulosic biomass with high cellulose content, realizing the carbonization of cellulose and hemicellulose with the dehydration, unsaturated bond formation, and aromatization. The produced hydrochar had an appearance of carbon microspheres, with high calorific values, abundant oxygen-containing functional groups, a certain degree of graphitization, and good thermal stability. Cellulose acts not only as a barrier to protect itself and hemicellulose from decomposition, but also as a key precursor for the formation of carbon microspheres. This study shows a promising method for synthesizing carbon materials from lignocellulosic biomass with a carbon-negative effect.

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