Polymer-based EMI shielding composites with 3D conductive networks:A mini-review

High-frequency electromagnetic waves and electronic products can bring great convenience to people’s life,but lead to a series of electromagnetic interference(EMI)problems,such as great potential dangers to the normal operation of elec-tronic components and human safety.Therefore,the research of EMI shield-ing materials has attracted extensive attention by the scholars.Among them,polymer-based EMI shielding materials with light weight,high specific strength,and stable properties have become the current mainstream.The construction of 3D conductive networks has proved to be an effective method for the prepara-tion of polymer-based EMI shielding materials with excellent shielding effective-ness(SE).In this paper,the shielding mechanism of polymer-based EMI shield-ing materials with 3D conductive networks is briefly introduced,with emphasis on the preparation methods and latest research progress of polymer-based EMI shielding materials with different 3D conductive networks.The key scientific and technical problems to be solved in the field of polymer-based EMI shielding materials are also put forward.Finally,the development trend and application prospects of polymer-based EMI shielding materials are prospected.

B-doped SiO_(x) composite with three dimensional conductive network for high performance lithium-ion battery anode

Currently,the practical application of SiO_(x) still has a huge hindrance in the area of lithium ion battery,because it is unable to achieve an effective contact with surrounding conducting materials,resulting in failure to form lithium ion migration tunnels.In this work,we presented a facile method to synthesize the B-doped SiOx composite by adhering SiO_(x) particles with MWCNT(multi-walled carbon nanotube)under the assistance of lithium metaborate(LiBO_(2)).LiBO_(2),as a sintering aid,not only can react with SiO_(x) to form a compacted framework,but also build a three-dimensional(3D)conductive network for ions transportation.Furthermore,B-SiO_(x)@CNT@LBO anode delivers a remarkable lithium storage performance in terms of long cycles and high rate capability.A full cell coupled with NCM622 cathode achieves a high energy density of 429.5 Wh kg^(-1) based on the total mass of cathode.

Core-shell Ni_(3)Sn_(2)@C particles anchore d on 3D N-dope d porous carbon skeleton for modulated electromagnetic wave absorption

Synthesizing multi-component composites via a straightforward,reliable,and scalable approach has been challenging.Herein,a three-dimensional nitrogen-doped porous carbon decorated with core-shell Ni_(3)Sn_(2)@carbon particles(3D N-PC/Ni_(3)Sn_(2)@C)was customized through a simple salt-template pyrolysis approach.The formed Ni_(3)Sn_(2) particles are perfectly surrounded by crystalline carbon layers and em-bedded in 3D carbon walls during pyrolysis.The dual protection of crystalline carbon layers and porous carbon walls guarantees the electrical conductivity and stability of Ni_(3)Sn_(2).The intriguing 3D and core-shell structure coupled with the introduction of multiple components empowers the composite with rich heterogeneous interface and conductive network,and contributes to the lightweight,corrosion resistance,oxidation resistance,and superior stability of electromagnetic(EM)wave absorbers.The N-PC/Ni_(3)Sn_(2)@C possesses the minimum reflection loss(RL min)of-54.01 dB and wide effective absorption bandwidth(EAB)of 7.36 GHz under a low filler content of less than 10%.The concept in the work proposes a facile,eco-friendly,and scalable pathway for the synthesis of other heterogeneous structures of EM wave ab-sorbers.

Monoclinic Cu_(3)(OH)_(2)V_(2)O_(7)·2H_(2)O nanobelts/reduced graphene oxide:A novel high-capacity and long-life composite for potassium-ion battery anodes

Developing suitable anode materials for potassium-ion batteries(PIBs)remains a great challenge owing to the limited theoretical capacity of active materials and large radius of K+ion(1.38?).To solve these obstacles,by integrating the principles of multielectron transfer and rational porous crystal framework,we creatively propose the monoclinic Cu_(3)(OH)_(2)V_(2)O_(7)·2H_(2)O(CVO)as a novel anode for PIBs.Furthermore,inspired by the metastable nature of CVO under high temperature/pressure,we skillfully design a facile hydrothermal recrystallization strategy without the phase change and surfactants addition.Thus,for the first time,the porous composite of Cu_(3)(OH)_(2)V_(2)O_(7)·2H_(2)O nanobelts covered in situ by reduced graphene oxide(CVO NBs/r GO)was assembled,greatly improving the deficiencies of CVO.When used as a novel anode for PIBs,CVO NBs/r GO delivers large specific capacity(up to 551.4 m Ah g^(-1)at 50 m A g^(-1)),high-rate capability(215.3 m Ah g^(-1)at 2.5 A g^(-1))and super durability(203.6 m Ah g^(-1)at 500 m A g^(-1)even after 1000 cycles).The outstanding performance can be ascribed to the synergistic merits of desirable structural features of monoclinic CVO nanobelts and the highly conductive graphene 3D network,thus promoting the composite material stability and electrical/ionic conductivity.This work reveals a novel metal vanadate-based anode material for PIBs,would further motivate the subsequent batteries research on M_(3)(OH)_(2)V_(2)O_(7)-n H_(2)O(M;Co,Ni,Cu,Zn),and ultimately expands valuable fundamental understanding on designing other high-performance electrode materials,including the combined strategies of multielectron transfer with rational porous crystal framework,and the composite fabrication of 1D electrode nanostructure with conductive carbon matrix.

In-situ One-pot Preparation of LiFePO_4/Carbon-Nanofibers Composites and Their Electrochemical Performance

A novel in-situ route was employed to synthesize LiFePO4/carbon-nanofibers （CNFs） composites. The route combined high-temperature solid phase reaction with chemical vapor deposition （CVD） using Fe2O3 and LiH2PO4 as the precursors for LiFePO4 growth and acetylene （C2H2） as the carbon source for CNFs growth. The composites were characterized by X-ray diffraction （XRD）, Brunauer-Emmett-Teller （BET） specific surface area, field emission scanning electron microscopy （FE-SEM）, and transmission electron microscopy （TEM）. The electrochemical performance of the composites was studied by galvanostatic cycling and cyclic voltammetry （CV）. The results showed that the in-situ CNFs growth could be realized by the catalytic effect of the Fe2O3 precursor. The sample after 80 min CVD reaction showed the best electrochemical performance, indicating a promising application in high-power Li-ion batteries.

Facile Preparation of NiO@graphene Nanocomposite with Superior Performances as Anode for Li-ion Batteries

Transition metal oxides gain considerable research attentions as potential anode materials for lithium ion batteries,but their applications are hindered due to their poor electronic conductivity,weak cycle stability and drastic volume change.Here,a NiO@graphene composite with a unique 3D conductive network structure is prepared through a simple strategy.When applied as anode material for Li-ion batteries,at 50 mA g^(−1),the NiO@graphene displays a high reversible capacity of 1366 mAh g^(−1) and a stable cyclability of 205 mAh g^(−1) after 500 cycles.Even at a high rate of 10 A g^(−1),it displays a favorable reversible capacity of 711 mAh g^(−1).Remarkably,when it recovers back to 0.05 A g^(−1),a reversible capacity of 1741 mAh g^(−1) is achieved.Thus,the NiO@graphene composite with 3D structure shows good application prospects as an alternative anode for advanced lithium ion batteries.

An Advanced Design Concept of Mansion-like Freestanding Silicon Anodes with Improved Lithium Storage Performances

To conquer inherently low conductivity,volume swelling,and labile solid electrolyte interphase(SEI)films of Si anode in lithium ion battery(LIBs),it is widely accepted that appropriate structure design of Si-C hybrids performs effectively,especially for nanosize Si particles.Herein,inspired by the sturdy construction of high-rise buildings,a mansion-like 3D structured Si@SiO_(2)/PBC/RGO(SSPBG)with separated rooms is developed based on 0D core-shell Si@SiO_(2),1D pyrolytic bacterial cellulose(PBC)and 2D reduced graphene oxide(RGO).Therefore,these hierarchical protectors operate synergistically to inhibit the inevitable volume changes during electrochemical process.Specifically,tightly coated SiO_(2)shell as the first protective layer could buffer the volume expansion and reduce detrimental pulverization of Si NPs.Furthermore,flexible spring-like PBC and ultra-fine RGO sheets perform as securer barriers and skeleton which will counteract the microstructure strain and accelerate electron transfer at the same time.Remarkably,the self-supporting electrode realizes a distinguished performance of 901 mAh g^(-1)at 2 A g^(-1)for 500 cycles.When matched with LiFePO4 cathodes,high stability of more than 100 cycles has been realized for the full batteries.