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Abstract Highly sensitive conductive polymer composites for piezoresistive sensing are developed by a design of the formulation variables of extrusion-based manufacturing (filler type/amount, polymer amount) and annealing (a), considering thermoplastic polyurethane (TPU) and/or olefin block copolymer (OBC) as polymer matrix and carbon black (CB) as conductive filler. With ternary composites - based on a CB type with stronger filler-matrix interactions and an appropriate OBC/TPU blend mass ratio (40/60 with CB amount of 5–10 m%; 50/50 with CB amount of 10 m%), the challenging region of both high sensitivity and static strain (maximal gauge factors (GF max) > 50 and ε max > 100%) can be realized: GF max > 104 and ε max = 20–240%. OBC binary composites with a high CB 2 amount (e.g. 15 m%) are however needed for ultrahigh static strains (ε max > 600%). Well-designed ternary composites (e.g. OBC 40 -CB/TPU 60 -7-a and OBC 30 -CB/TPU 70 -7-a) possess a large dynamic resistance change, negligible hysteresis and high stability and display strain sensor application potential. Highly CB 2 loaded binary (≥12 m%) and ternary composites (10 m%) exhibit a more obvious strain-dependent dynamic hysteretic behavior, as they switch from a dual peak to single peak pattern toward the sensing strain limit, which is interesting for self-diagnose. [ABSTRACT FROM AUTHOR]

A novel integrated strategy is proposed to construct the LiNi 0.9 Co 0.09 W 0.01 O 2 with simultaneous spinel phase and Li 2 TiO 3 conductive network, which can enhance the lithium-ion migration kinetics and structural stability of ultrahigh-Ni cathode materials. [Display omitted] The tungsten with high oxidation states (W6+) had been proved to effectively improve the electrochemical performance of ultrahigh-nickel (Ni ≥ 90 %) cathode materials due to the unique microstructures. However, the exat location and underlying action mechanism of tungsten are still not well-understood, and there have been no reports on in-situ modification from bulk to surface simultaneously for these novel cathode materials. Here, a novel integrated strategy is proposed for in-situ modification of LiNi 0.9 Co 0.09 W 0.01 O 2 (NCW). Innovatively, the introduction of nano spinel phase and titanium pinned into the lattice further suppresses the anisotropic variation of unit cell and promotes the lithium-ion migration kinetics within the bulk. Additionally, the Li 2 TiO 3 conductive network enhances migration kinetics across interface and protects the active material against electrolyte erosion. Furthermore, the combination of in-situ analysis and DFT calculation reveals the ordered distribution of tungsten and the suppression effects of titanium on phase transition and cobalt redox. Consequently, the titanium-modified NCW exhibits significantly improved electrochemical performance, such as capacity retention of 93.0 % at 1C after 500 cycles in pouch-type full-cell, along with stable lattice oxygen during operation. [ABSTRACT FROM AUTHOR]

Flexible and stretchable piezoresistive strain sensors which can translate mechanical stimuli (strain changes) into electrical signals (resistance changes) provide a simple and feasible detection tool in the field of health/damage monitoring, human motion detection, personal healthcare, human-machine interfaces, and electronic skin. Herein a detailed overview is presented on both strategies for sensing performance improvement and progress to medium or large-scale fabrication. A broad range of matrices/substrates and incorporated nanomaterials is covered and attention is paid to the current state-of-the-art of feasible but low-cost manufacturing methods. The sensor design parameters include sensitivity (gauge factor), stretchability, linearity, hysteresis, biocompatibility, and self-healing potential. Starting from fundamental sensing mechanisms, i.e. the tunneling effect, the disconnection mechanism, and the crack propagation mechanism, examples are provided from lab to application scale. [ABSTRACT FROM AUTHOR]

Na 3 Zr 2 Si 2 PO 12 (NZSP) solid-state electrolyte is considered one of the most promising solid-state electrolyte because of their excellent electrochemical and thermal stability. Even though, the low conductivity of NZSP solid-state electrolytes hinders practical application. Therefore, an anions/cations co-assisting strategy is proposed by introducing the Zn2+ and F−. The influence of adding different amounts of Zn2+ and F− on the Na+ conductivity of NZSP was investigated computationally and experimentally. The Zn2+/F− co-assisting (Na 3.3 Zr 1.85 Zn 0.15 Si 2 PO 12) solid-state electrolyte exhibits the ionic conductivity of 0.722 mS cm−1 at 30 °C, and the activation energy of ∼0.237 eV. Its applicability in a solid-state battery is tested, and the assembled Na/Na 3 V 2 (PO 4) 3 (NVP) battery exhibits an outstanding electrochemical performance of 98.4% capacity retention after being cycled at 0.5 C. Moreover, DFT calculations also have been used to demonstrate the effect of doping on the crystal structure and space migration energy barrier. This research provides new ideas for improving the electrochemical properties of inorganic solid electrolytes. • A new method for anionic/cations to co-assisting improve the ionic conductivity of solid electrolytes. • The Zn2+ replaces Zr4+ to increase the conductivity of the bulk phase. • The F− can improve the sintering activity of ceramic materials to make the grains larger and denser. • The NZSP-0.15ZF solid electrolyte battery shows an ultrahigh capacity retention of 98.4% after 200 cycles. [ABSTRACT FROM AUTHOR]

Dual CEI/SEI protection layers formed by an inducing strategy are successfully realized for optimizing the stability of electrolyte/electrode interfaces and further improving the rate performance and cycling stability of SSLMBs. [Display omitted] Designing a robust cathode electrolyte interphase (CEI) on a high-voltage cathode and stable solid electrolyte interphase (SEI) on a Li anode is the key to success in developing solid-state Li metal batteries (SSLMBs). In this work, we design an inorganic compound-intensive CEI layer and a LiF-rich gradient SEI layer in SSLMBs through the in-situ polymerization of a novel multi-functional electrolyte. The inorganic compound-intensive CEI offers excellent electrochemical compatibility with high-voltage layered cathode LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM), while the LiF-rich gradient SEI successfully suppresses Li dendrite formation and harmful interfacial parasite reactions. As a result, SSLMBs present a remarkable rate performance of 182 mAh g−1 at 1 C and a long cycling stability of 88.6% capacity retention after 300 cycles at room temperature. The fundamental insights into interface chemistry and facile strategy demonstrated in this work could assist the rapid development of SSLMBs toward remarkable performance. [ABSTRACT FROM AUTHOR]

As a novel thermoplastic elastomer, olefin block copolymers (OBCs) show a tremendous application potential in many areas. However, the practical use of OBCs is mainly restricted to the low load-bearing environments because of its poor low-strain mechanical strength and stiffness. In this work, short Kevlar fiber was introduced into OBC matrix to improve its mechanical properties. The results show that introduction of pristine Kevlar fiber only gives rise to a slight increase in tensile strength of OBC owing to the poor interfacial strength, regardless of the presence of compatibilizer maleic anhydride-grafted polypropylene (MA-g-PP). However, a largely enhanced tensile strength can be easily obtained when hydrolyzed or polydopamine-coated Kevlar fiber was incorporated into the OBC matrix using the MA-g-PP as the reactive compatibilizer. More importantly, the tensile strength can be further enhanced with the orientation of Kevlar fiber in the composites. As compared with compression molded composites with randomly orientated fibers, injection molded composites with highly oriented fibers exhibit a significantly higher tensile strength at the same composition. Moreover, it is interesting to observe that Kevlar fiber can be easily exfoliated into several microfibers during melt-mixing with OBC, but the exfoliation has no evident effect on the reinforcement effect possibly because of the poor interfacial strength between the newly-formed microfibers and the OBC matrix. Our work demonstrates that mechanical performance of short fiber reinforced elastomer composites could be significantly improved by enhancing interfacial strength and fiber orientation using a facile surface modification strategy and conventional melt-processing technology. [ABSTRACT FROM AUTHOR]

Abstract: Conductive network morphology and interfacial interaction play important roles in determining resistivity–strain (ρ–ε) sensing behavior of conductive polymer composites (CPCs). In this work, thermoplastic elastomer blends consisting of poly(styrene–butadiene–styrene) block polymer (SBS) and thermoplastic polyurethane (TPU) were fabricated via different melt processing procedures, which could tune the above two issues simultaneously by selectively localizing multi-walled carbon nanotubes (MWCNTs) in SBS, TPU and both in SBS and TPU, respectively. It is observed that the composite fibers with selectively localized MWCNTs show distinct different ρ–ε sensing behavior. Work of adhesion calculation suggests stronger interfacial interaction between MWCNTs and SBS, however, wetting coefficient calculation indicates slightly better wetting of MWCNTs with TPU. Because of such stronger interaction and poorer dispersion, the composite fiber with MWCNTs distributed in SBS exhibits higher ρ–ε sensitivity than its counterpart with MWCNTs distributed in TPU, and with MWCNTs distributed in both phases, the ρ–ε sensitivity lies in between. Moreover, the ρ–ε sensing behavior was fitted with a model based on tunneling theory by Simmons. It is suggested that the change in tunneling distance and the number of conductive pathways could be accelerated significantly under strong interfacial interaction. This study could offer a new pathway and provide a guideline for the preparation of high-performance CPC resistivity–strain sensors with tunable sensitivity. [Copyright &y& Elsevier]