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Low‐grade heat is ubiquitous in the environment and its thermoelectric conversion by the ionic conductors remains a challenge because of the low efficiency and poor sustainability. Here we demonstrate that the thermoelectric performances can be boosted by combining the Soret effect of protons and proton‐coupled electron transfer (PCET) reaction of benzoquinone and hydroquinone in hydrogels. An overall enhancement of thermopower (25.9 mV K−1), power factor (5 mW m−1 K−2), figure of merit (>2.4) and continuity of power output is achieved. Moreover, an energy‐storage function can be achieved by the redox couple, and a retained power output of 27.7 %, or 14 mW m−2 for more than 3 hours is obtained by the re‐balance of PCET reactants in the hydrogel after the removal of the temperature gradient. [ABSTRACT FROM AUTHOR]

Solid inorganic and polymeric electrolytes have the potential to enable rechargeable batteries with higher energy densities, compared to current lithium-ion technology, which uses liquid electrolyte. Inorganic materials such as ceramics and glasses conduct lithium ions well, but they are brittle, which makes incorporation into a battery difficult. Polymers have the flexibility for facile use in a battery, but their transport properties tend to be inferior to inorganics. Thus, there is growing interest in composite electrolytes with inorganic and organic phases in intimate contact. This article begins with a discussion of ion transport in single-phase electrolytes. A dimensionless number (the Newman number) is presented for quantifying the efficacy of electrolytes. An effective medium framework for predicting transport properties of composite electrolytes containing only one conducting phase is then presented. The opportunities and challenges presented by composite electrolytes containing two conducting phases are addressed. Finally, the importance and status of reaction kinetics at the interfaces between solid electrolytes and electrodes are covered, using a lithium-metal electrode as an example.

Solid-state electrolytes can offer improved lithium-ion battery safety while potentially increasing the energy density by enabling alkali metal anodes. There have been significant research efforts to improve the ionic conductivity of solid-state electrolytes and the electrochemical performance of all-solid-state batteries; however, the root causes of their poor performance - interfacial reaction and subsequent impedance growth - are poorly understood. This is due to the dearth of effective characterization techniques for probing these buried interfaces. In situ and operando methodologies are currently under development for solid-state interfaces, and they offer the potential to describe the dynamic interfacial processes that serve as performance bottlenecks. This article highlights state-of-the-art solid-solid interface probing methodologies, describes practical limitations, and describes a future for dynamic interfacial characterization.

Reactive flash synthesis simplifies the processing of complex ceramics such as alumina doped lithium lanthanum zirconate. Low temperatures and short processing times obviate the loss of lithium while producing dense single-phase ceramics. Here we show the synthesis of non-stoichiometric compositions of this ceramic which increases the ionic conductivity by a factor of more than three. The non-stoichiometry refers to non-equilibrium lithium/lanthanum ratio, and to the addition of boron to produce excess lithium-ion vacancies. The results open the possibility of using non-stoichiometry as a concept, and RFS as the tool, for the discovery of new compositions that enhance lithium-ion conductivity. [ABSTRACT FROM AUTHOR]

Li 2 O-2B 2 O 3 coated Li 4 Ti 5 O 12 anode with protected particle surface and fast ion transfer exhibit desired rate capability and cycling stability for lithium ion batteries. Li 2 O-2B 2 O 3 (LBO) ionic conductor with high conductivity plays an important role in boosting the rate performance and cycling stability of Li 4 Ti 5 O 12 (LTO) anode for lithium-ion batteries by preventing direct exposure of LTO to the electrolyte. Herein, the effect of LBO coating layer on lithium ion (Li+) storage performance is investigated in detail by adjusting the adding amount of LBO precursor dispersion. LTO coated with 2 wt% LBO achieves an optimum performance with a specific capacity of 172.9 mA h g−1 at a current density of 0.1 A g−1, an improved rate capability (specific capacity of 127.9 mA h g−1 is maintained when the current density is 20 times than 0.1 A g−1) and a remarkable cycling stability (capacity retention of 94.2% after 4000 cycles at 2.0 A g−1). These LBO-LTO composites are competitive and promising candidates for electrochemical energy storage and other applications. [ABSTRACT FROM AUTHOR]

Atomic force microscopy (AFM)-based impedance spectroscopy provides localized impedance information of materials and interfaces at the nanoscale by utilizing the conductive AFM tip as a moving electrode to detect current response as a function of time and frequency under controlled environments. This capability enables AFM-based nanoscale impedance measurements to play a unique role in enhancing our understanding of many electronic and electrochemical devices. This article introduces the central concepts of AFM-based impedance measurement and reviews recent examples applying this technique to a variety of functional materials systems, in particular focusing on fuel cells, lithium-ion batteries, photoactive biomembranes, as well as other application examples. [ABSTRACT FROM PUBLISHER]

The design and control of materials properties, often at the nanoscale, are the foundation of many new strategies for energy generation, storage, and efficiency. Scanning probe microscopy (SPM) has evolved into a very large toolbox for the characterization of properties spanning size scales from hundreds of microns to nanometers. Recent advances in SPM involve properties and size scales of precise relevance to energy-related materials, as presented in this issue. These advances are put into the general context of energy research, and the general principles are summarized. [ABSTRACT FROM PUBLISHER]

• Molten-state polymer electrolyte precursor was infused into a composite electrode. • The infused PIC enables the formation of percolating Li+ conduction pathways. • The interfacial solid-solid contact issues of SSB are mitigated by the PIC infusion. • The microstructural engineering results in enhanced performance of SSB. • The efficacy of the PIC infusion is demonstrated in a bipolar SSB. Solid-state batteries (SSBs) offer a promising technical solution to meet the key requirements of future energy storage systems, i.e., safety and high energy density. However, the realization of SSBs is hindered by low electrode performance that results from poorly controlled solid-solid contacts. Herein, we propose an effective strategy for tailoring conductive networks and reaction interfaces via the viscosity-controlled infusion of a molten-state polymer electrolyte precursor (polymer ionic conductor, PIC) into a porous composite electrode (CE). A poly(ethylene glycol)-based PIC penetrates a three-dimensional pore network of the CE and transforms to a highly viscous, stable phase under battery operating conditions. The infused PIC enables the formation of percolating Li+ conduction pathways as well as intimate solid-solid reaction interfaces, which leads to the full utilization of the CE at high mass loadings. SSBs assembled with PIC-infused LiFePO 4 -CEs exhibit superior capacity (154 mAh g−1), rate-capability, and cycling stability than SSBs with unmodified CEs. Moreover, a 10 V-class, bipolar-pouch SSB fabricated using the PIC-infusion technology shows reversible charge–discharge operations without a considerable performance loss. This study demonstrates that the proposed microstructural engineering provides an effective approach to resolving the interfacial solid-solid contact issues of SSBs and can be used to fabricate safe, high-energy, long-cycling SSBs. [ABSTRACT FROM AUTHOR]

Gel polymer electrolytes (GPEs) have attracted abundant attentions due to its higher ion conductivity and better compatibility with electrode than the inorganic solid-state electrolytes and safer than the liquid electrolytes. In this work, sodium conductive Na 3 Zr 2 Si 2 PO 12 nanoparticles modified PVDF-HFP/PMMA/TPU-based GPEs are prepared and its application performances in sodium ions batteries (SIBs) are demonstrated. The addition of Na 3 Zr 2 Si 2 PO 12 filler decreases the crystallinity of polymer matrix and improves the porosity of GPEs membranes, resulting in the increasing of liquid electrolyte uptake. As a result, the Na 3 Zr 2 Si 2 PO 12 filler modified GPEs delivers enhanced ion conductivity as high as 2.83 × 10−3 S cm−1 with a small activation energy of ~0.039 eV and enlarged electrochemical window width of 5.16 V. Application in SIBs, high first discharge capacity of 92.7 mAh·g−1 at 0.5C and promising capacity retention capability (99.2% after 100 cycles) as well as excellent rate performance (83.9 mAh·g−1 at 5C) are recorded for the obtained GPEs. These results suggest that the performances of PVDF-HFP/PMMA/TPU-based GPEs can be enhanced obviously by adding conductive Na 3 Zr 2 Si 2 PO 12 filler, promoting the practical application of GPEs in energy storage devices. • PVDF-HFP/PMMA/TPU-Na 3 Zr 2 Si 2 PO 12 composite gel polymer electrolyte was fabricated. • Ionic conductivity of GPE was enhanced with the presence of Na 3 Zr 2 Si 2 PO 12 filler. • Na 3 Zr 2 Si 2 PO 12 filler decreased the crystallinity and enlarged the porosity of GPE. • GPE delivered competitive electrochemical performances applied in SIBs. [ABSTRACT FROM AUTHOR]