3D printing encouraging desired in-situ polypyrrole seed-polymerization for ultra-high energy density supercapacitors

The tireless pursuit of supercapacitors with high energy density entails the parallel advancement of wellsuited electrode materials and elaborately engineered architectures.Polypyrrole(PPy)emerges as an exceedingly conductive polymer and a prospective pseudocapacitive materials for supercapacitors,yet the inferior cyclic stability and unpredictable polymerization patterns severely impede its real-world applicability.Here,for the first time,an innovative seed-induced in-situ polymerization assisted 3D printing strategy is proposed to fabricate PPy-reduced graphene oxide/poly(vinylidene difluoride-cohexafluoropropylene)(PVDF-HFP)(PPy-rGO/PH)electrodes with controllable polymerization behavior and exceptional areal mass loading.The preferred active sites uniformly pre-planted on the 3D-printed graphene substrates serve as reliable seeds to induce efficient polypyrrole deposition,achieving an impressive mass loading of 185.6 mg cm^(-2)(particularly 79.2 mg cm^(-2)for polypyrrole)and a superior areal capacitance of 25.2 F cm^(-2)at 2 mA cm^(-2)for a 12-layer electrode.In agreement with theses appealing features,an unprecedented areal energy density of 1.47 mW h cm^(-2)for a symmetrical device is registered,a rarely achieved value for other PPy/rGO-based supercapacitors.This work highlights a promising route to preparing high energy density energy storage modules for real-world applications.

Chemical interaction motivated structure design of layered metal carbonate hydroxide/MXene composites for fast and durable lithium ion storage

Rational architecture design has turned out to be an effective strategy in improving the electrochemical performance of electrode materials for batteries.However,an elaborate structure that could simultaneously endow active materials with promoted reaction reversibility,accelerated kinetic and restricted volume change still remains a huge challenge.Herein,a novel chemical interaction motivated structure design strategy has been proposed,and a chemically bonded Co(CO_(3))_(0.5)OH·0.11 H_(2)O@MXene(CoCH@MXene)layered-composite was fabricated for the first time.In such a composite,the chemical interaction between Co^(2+)and MXene drives the growth of smaller-sized CoCH crystals and the subsequent formation of interwoven CoCH wires sandwiched in-between MXene nanosheets.This unique layered structure not only encourages charge transfer for faster reaction dynamics,but buffers the volume change of CoCH during lithiation-delithiation process,owing to the confined crystal growth between conductive MXene layers with the help of chemical bonding.Besides,the sandwiched interwoven CoCH wires also prevent the stacking of MXene layers,further conducive to the electrochemical performance of the composite.As a result,the as-prepared CoCH@MXene anode demonstrates a high reversible capacity(903.1 mAh g^(-1)at 100 mA g^(-1))and excellent cycling stability(maintains 733.6 mAh g^(-1)at1000 mA g^(-1)after 500 cycles)for lithium ion batteries.This work highlights a novel concept of layerby-layer chemical interaction motivated architecture design for futuristic high performance electrode materials in energy storage systems.

双碳背景下《材料科学与工程选论》课程教学改革探讨

针对全球资源、能源、环境、气候等问题,中国提出碳达峰、碳中和的“双碳”目标,旨在推动经济社会的绿色低碳发展,同时也对高校相关材料类专业课程提出了新的更高要求。本文结合笔者自身教学实践,以四川大学高分子材料与工程专业研究生必修课《材料科学与工程选论》为例,分析了目前课程现状,提出将“双碳”理念融入课程教学中,从课程内容设计、教学模式改革等方面探讨了“双碳”背景下具有全球可持续发展视野的科技创新人才培养模式。

Insight into Cellulose Nanosizing for Advanced Electrochemical Energy Storage and Conversion:A Review

Living in a world of heavy industrialization and confronted by the ever-deteriorating environment,the human race is now undertaking serious efforts to reach the target of carbon neutrality.One major step is to promote the development of sustainable electrochemical energy storage and conversion technologies based on green resources instead of the traditional nonreusable petroleum-based technologies.As an almost inexhaustible bioresource,nanocellulose derived from natural biomass exhibits outstanding physiochemical properties that could be well leveraged to bring about numerous opportunities for electrochemical processes.Through structure engineering,nanocellulose with a width of a few tens of nanometers and a length of up to micrometers could be realized.The drastic reduction in dimensions leads to superior mechanical,optical,and functional properties inaccessible to the bulky cellulose counterpart.In this review,different types of nanocellulose with distinctive physiochemical properties and their respective preparation methods are first examined.This is followed by a detailed and insightful analysis of the superiority and unprecedented performance gains that nanocellulose imparts to different electrochemical energy storage and conversion applications as a result of nanosizing.Finally,we humbly put forward our perspectives on the problems regarding current studies as well as on the future research direction for nanocellulose-mediated electrochemical processes to enable practical applications.This review is intended as guidance to initiate cross-disciplinary research effort in this engaging field and help evoke inspiration to effect solutions to critical energy issues of the day.

3D printing CO_(2)-activated carbon nanotubes host to promote sulfur loading for high areal capacity lithium-sulfur batteries

Lithium-sulfur batteries(LSBs)have emerged as a promising high energy density system in miniaturized energy storage devices.However,serious issues rooted in large volume change(80%),poor intrinsic conductivity,“shuttle effect”of S cathode,and limited mass loading of traditional electrode still make it a big challenge to achieve high energy density LSBs in a limited footprint.Herein,an innovative carbon dioxide(CO_(2))assisted three-dimensional(3D)printing strategy is proposed to fabricate threedimensional lattice structured CO_(2)activated single-walled carbon nanotubes/S composite thick electrode(3DP S@CNTs-CO_(2))for high areal capacity LSBs.The 3D lattice structure formed by interwoven CNTs and printed regular macropores can not only act as fast electron transfer networks,ensuring good electronic conductivity of thick electrode,but is beneficial to electrolyte infiltration,effectively boosting ion diffusion kinetics even under a high-mass loading.In addition,the subsequent hightemperature CO_(2)in-situ etching can induce abundant nanopores on the wall of CNTs,which significantly promotes the sulfur loading as well as its full utilization as a result of shortened ion diffusion paths.Owing to these merits,the 3DP S@CNTs-CO_(2)electrode delivers an impressive mass loading of 10 mg·cm^(−2).More importantly,a desired attribute of linearly scale up in areal capacitance with increased layers is observed,up to an outstanding value of 5.74 mAh·cm^(−2),outperforming most reported LSBs that adopt strategies that physically inhibit polysulfides.This work provides a thrilling drive that stimulates the application of LSBs in new generation miniaturized electronic devices.

3D printing of fast kinetics reconciled ultra-thick cathodes for high areal energy density aqueous Li–Zn hybrid battery

The limitation of areal energy density of rechargeable aqueous hybrid batteries(RAHBs)has been a significant longstanding problem that impedes the application of RAHBs in miniaturized energy storage.Constructing thick electrodes with optimized geometrical properties is a promising strategy for achieving high areal energy density,but the sluggish ion/electron transfer and poor mechanical stability,as well as the increased electrode thickness,itself present well-known problems.In this work,a 3D printing technique is introduced to construct an ultra-thick lithium iron phosphate(LFP)/carboxylated carbon nanotube(CNT)/carboxyl terminated cellulose nanofiber(CNF)composite electrode with uncompromised reaction kinetics for high areal energy density Li–Zn RAHBs.The uniformly dispersed CNTs and CNFs form continuous interconnected 3D networks that encapsulate LFP nanoparticles,guaranteeing fast electron transfer and efficient stress relief as the electrode thickness increases.Additionally,multistage ion diffusion channels generated from the hierarchical porous structure assure accelerated ion diffusion.As a result,LFP/Zn hybrid pouch cells assembled with 3D printed electrodes deliver a well-retained reversible gravimetric capacity of about 143.5 mAh g^(-1) at 0.5 C as the electrode thickness increases from 0.52 to 1.56 mm,and establish a record-high areal energy density of 5.25 mWh cm^(-2) with an impressive utilization of active material up to 30 mg cm^(-2) for an ultra-thick(2.08 mm)electrode,which outperforms almost all reported zinc-based hybrid-ion and single-ion batteries.This work opens up exciting prospects for developing high areal energy density energy storage devices using 3D printing.