To push the upper limit of capacitive materials, the integration of multi-modal capacitive materials has emerged as a potential solution. In this regard, we reported the novel binary composite of self-suspended polyaniline (S-PANI) and multi-walled carbon nanotubes (MWNTs). Compared with conventional polyaniline, S-PANI offers higher porosity and fibrillar polymeric network, which was achieved by doping long-chain protonic acid during in situ polymerization. S-PANI was loaded on oxidized carbon nanotubes (OCNTs) and sulfonated carbon nanotubes (SCNTs) to prepare S-PANI/OCNT and S-PANI/SCNT composite electrodes, respectively. The conductive and exclusive fibrillar S-PANI provide unobstructed channels for charge transport and electrolyte infiltration. Preliminary electrochemical studies revealed that the capacitance of the composite electrode reached 316.8 F g(-1) and 345.4 F g(-1), and established exceptional capacitance retention rates of 92.8% and 93.7% after 5000 cycles for S-PANI/OCNT and S-PANI/SCNT composite, respectively, making it a potential candidate for imminent energy storage devices.

Flexible dielectric materials with high energy density and remarkable charge-discharge efficiency are currently in great demand for the field of energy storage. On the other hand, it is also urgent to develop renewable, biodegradable and environmentally friendly dielectric materials. In this work, Al2O3 nanoparticles (AO) with a diameter of similar to 10 nm were incorporated into regenerated cellulose matrix (RC) without extra treatment to fabricate environment-friendly RC-AO dielectric nanocomposites via a simple dissolution/regeneration pathway. Effects of Al2O3 nanoparticles on the structure and dielectric properties of RC-AO nanocomposite films were systemically investigated. The results showed that the RC-AO films exhibited excellent comprehensive performance, including increased dielectric constant, reduced dielectric loss, improved breakdown strength and high energy storage density. Particularly, the high energy density of 5.7 J cm(-3) was achieved at the breakdown strength of 380 MV m(-1) when the Al2O3 content was 5 wt%. Furthermore, the composites possessed excellent thermal conductivity, stability and mechanical property. This work provides a good choice for the development of high-performance and 'green' natural polymer-based dielectric materials.

随着不可再生资源及能源的枯竭和环境的日益恶化,开发环境友好、可再生的生物质材料,并用其解决能源问题具有重大意义。因此,可再生的纤维素材料受到了研究者的广泛关注。本文主要以再生纤维素代替传统的石油基聚合物为基体,研究纯再生纤维素膜的介电性能,同时再分别与聚多巴胺包覆粉煤灰（FA@DA）和剥离的氮化硼纳米片（BNNS）复合,通过提高复合膜的介电常数和击穿强度来提高再生纤维素复合膜的储能密度。主要结论如下:（1）以氢氧化钠/尿素/水体系溶解纤维素,分别利用5%硫酸水溶液、5%硫酸/5%硫酸钠水溶液、丙酮、叔丁醇作为再生浴,通过不同的干燥条件（60℃干燥,25℃干燥,25℃真空-加压干燥）,制备性能不同的纯再生纤维素膜。将薄膜置于不同的湿度环境中放置72 h后进行介电性能测试,实验发现无机溶液作为再生浴制备的再生纤维素膜具有较高的介电常数和较大的介电损耗,但击穿强度较小;在25℃真空-加压条件下干燥的薄膜具有较小的介电常数和介电损耗,但击穿强度得到明显提高,总体上利用丙酮和真空-加压条件制备的薄膜具有最高的储能密度,在205 MV m-1的击穿强度下储能密度达到1.23J cm-3。另外,随着放置环境湿度的增大,薄膜的介电常数和介电损耗以及电导率同时大幅度增大,而击穿强度急剧下降。（2）以粉煤灰（FA）和聚多巴胺包覆粉煤灰（FA@DA）作为填料与纤维素复合,研究了复合材料的结构和介电储能性能。扫描电镜结果显示,与没有改性的粉煤灰相比,多巴胺包覆的粉煤灰与再生纤维素具有更好的相容性,热重结果显示复合膜具有良好的热稳定性。在添加FA@DA后,复合膜的介电常数和击穿强度明显提高,在添加量为50 wt%时,在100 Hz下,介电常数为11.9;在添加量为40 wt%时,优化制备条件击穿强度达到了330 MVm-1,储能密度达到最大,为3.47 J cm-3,充放电效率为68%。（3）直接利用氢氧化钠/尿素/水体系超声剥离六方氮化硼制备氮化硼纳米片,再在同一混合分散液中溶解纤维素制备再生纤维素/氮化硼复合薄膜（RC-BN）。扫描电镜结果表明复合膜具有规整的二维层状结构,热重结果表明复合膜具有良好的热稳定性,当BN填充量为30 wt%时,导热率达到2.97 W m-1K-1。介电性能测试显示,随着氮化硼的加入介电常数和介电损耗都有所下降,但击穿强度得到明显提高,在BN含量为10 wt%时,击穿强度达到370 MV m-1,储能密度达到4.01 J cm-3,充放电效率均大于75%。高温介电结果表明,对比于纯再生纤维素膜,RC-BN的介电性能具有优异的热稳定性。此外,RC-BN具有良好的透光性和拉伸强度以及断裂伸长率。

随着科技的发展和环保意识的提高,人们对环境污染和能源短缺问题越来越关注。作为极具应用前景的材料,压电复合材料具有较高的压电性能、良好柔性及易成型加工等优点,使其可以应用于能量收集及智能穿戴设备等领域。近期有研究表明,当二硫化钼（MoS2）被剥离为单层时或少数奇数层时,具有良好的压电性能,然而,单独的二硫化钼性脆,不易成膜。TEMPO氧化法制备的纳米纤维素（TOCN）具有高长径比、良好机械性能和高结晶度等特点。纳米纤维素表面有大量带负电的基团,可以防止二硫化钼发生团聚,本文将剥离后的二硫化钼与纳米纤维素进行复合用来制备压电复合材料,研究不同质量分数的MoS2纳米片及空间结构对复合材料压电性能的影响,同时制备了TOCN/MoS2/BaTiO3压电复合膜。并将所制备的压电材料制成压电纳米发电机器件,探究其在收集环境中的能量和传感等领域的应用价值。具体工作内容与成果如下:（1）采用液相剥离法剥离二硫化钼,然后将剥离后的二硫化钼与TOCN进行复合,制备TOCN/MoS2复合膜。X射线衍射（XRD）和扫描电子显微镜（SEM）分析表明,TOCN纳米纤维内插层到二硫化钼层间,形成了良好的层状结构。当二硫化钼的添加量为4 wt.%时,TOCN/MoS2复合膜的压电应变常数(d33)最高达到31 pC/N,同时该组分制备的薄膜纳米发电机的开路电压为4.1V,短路电流为210 nA,可以在120 s内将10μF的商用电容器充电至1.6 V。（2）通过TOCN与二硫化钼的复合分散液制备TOCN/MoS2复合气凝胶,由于纳米纤维素气凝胶具有良好的三维网状结构,可以防止二硫化钼在基体内发生团聚。将所制的气凝胶在0.5 MPa的条件下进行压缩,制备多孔结构的气凝胶膜。多孔结构的材料在经过高压电极化后会形成多孔压电驻极体,其压电性能会明显的高于普通压电聚合物。利用多孔压电驻极体结构的复合气凝胶膜制备具有优异压电性能的纳米发电机。经测试发现,当二硫化钼的添加量为6wt.%时,TOCN/MoS2复合气凝胶膜压电纳米发电机的输出最高,其开路电压达到最大值42.5 V,短路电流达到1050 nA,输出功率为9.1μW,并能直接点亮一个商用发光二极管。（3）为了在提高压电性能的同时,同时保持材料的灵活性,本章采用了在TOCN/MoS2的基础上添加高压电性能的钛酸钡颗粒,制备三相复合膜。经测试,当添加钛酸钡后,TOCN/MoS2/BaTiO3三相复合膜的力学性能及压电性能均有提高。当钛酸钡的添加量为8 wt.%时,其开路电压最大值为8.2 V,短路电流达到440 nA,同时将所制备的复合膜纳米发电机用于微弱应力及人体生理信号的传感。

Advanced flexible supercapacitors with high energy/power density are an imperative research objective. In this study, a dually activated carbon cloth is designed as the functional current collector for supercapacitors. An electrodeposition technique is used for engineering Manganese Dioxide (MnO2) nanoflakes and profiting from a Poly (3,4 ethylene dioxythiophene; PEDOT) shield layer, a Li+-based neutral electrolyte high-performance freestanding asymmetric supercapacitors is constructed. The activated carbon cloth (ACC) provides an efficient electron-carrying route and the hierarchical nanostructure of the ACC@MnO2@PEDOT electrode. The integrated ACC@MnO2@PEDOT electrode exhibited exceptional capacitance performance of 1882.5 mF cm−2 (current density 1 mA cm−2) in 1.5 M aqueous LiCl electrolyte benefiting from ACC scaffold, the pseudocapacitive activity of MnO2 and substantial conductivity of the PEDOT polymer. Fabricating the structured electrode into an asymmetric supercapacitor revealed an enhanced areal energy density and an areal power density. The fabricated device demonstrated a broad voltage window of 1.8 V and extraordinary cycling stability of 94.6% after 10000 charge-discharge cycles. The unique scaffold, conducting PEDOT polymer, and MnO2 nanoflakes synergistically improved the cyclic performance and rate proficiency of the electrode, resulting in a supercapacitor with bendable electrical energy storage applications. © 2023 Elsevier B.V.

Solid-state cooling technology based on elastocaloric effects has shown potential advantages over traditional vapor-compression cooling systems owing to its high energy efficiency and zero green-house gas emissions. However, a lack of strategies for improving the elastocaloric activity of polymers remains the main obstacle to their commercialization since the elastocaloric effect was first investi-gated by J.P. Joule in natural rubber. Herein, we demonstrate that polymer elastomers with molecular chains near molecular -struc-ture-induced plastic-rubber critical transitions exhibit superior elastocaloric activity through reversible conformational changes. As the content of ethyl side groups in the soft block of polysty-rene-b-poly(ethylene-co-butylene)-b-polystyrene decreases from 33 to 8 mol %, the adiabatic temperature change increases from -4.3 to -16.3 K, and the isothermal entropy change increases from 38.5 to 173.3 J kg -1 K-1 , which thus shows the highest polymer elastocaloric activity near room temperature. This strategy could promote the commercialization of elastocaloric polymers in solid-state cooling applications.

Although the elastocaloric effect was found in natural rubber as early as 160 years ago, commercial elastocaloric refrigeration based on polymer elastomers has stagnated owing to their deficient elastocaloric effects and large extension ratios. Herein, we demonstrate that polymer elastomers with uniform molecular chain-lengths exhibit enormous elastocaloric effects through reversible conformational changes. An adiabatic temperature change of -15.3 K and an isothermal entropy change of 145 J kg(-1) K-1, obtained from poly(styreneb-ethylene-co-butylene-b-styrene) near room temperature, exceed those of previously reported elastocaloric polymers. A rotary-motion cooling device is tailored to high-strains characteristics of rubbers, which effectively discharges the cooling energy of polymer elastomers. Our work provides a strategy for the enhancement of elastocaloric effects and could promote the commercialization of solid-state cooling devices based on polymer elastomers.

Designing a realistic structure for transition metal oxides (TMOs) with high specific capacity and good stability is a critical challenge for the development of lithium-ion batteries (LIBs). Herein, we report an effective strategy to fabricate sulfonated carbon nanotubes (SCNT) chained Fe3O4 nanoparticles (SCNT/Fe3O4). Compared with acidized carbon nanotubes (CCNT), the nondestructive preparation process of SCNT made it retain high electron conductivity and acquired larger length-diameter ratio. The SCNT/Fe3O4 used as anode material delivered a high reversible capacity (674 mAh g(-1) at 500 mA g(-1) after 100 cycles) and excellent rate capability (402 mAh g(-1 )at 2 A g(-1) after 200 cycles). The excellent performance may be related to the faster electron transmission network and the more stable three-dimensional framework provided by SCNT. This work presents an approach to fabricate high-performance TMO-based composites for LIBs.