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Lithium-ion batteries (LIBs) are at the forefront of energy storage and highly demanded in consumer electronics due to their high energy density, long battery life, and great flexibility. However, LIBs usually suffer from obvious capacity reduction, security problems, and a sharp decline in cycle life under low temperatures, especially below 0 °C, which can be mainly ascribed to the decrease in Li+ diffusion coefficient in both electrodes and electrolyte, poor transfer kinetics on the interphase, high Li+ desolvation barrier in the electrolyte, and severe Li plating and dendrite. Targeting such issues, approaches to improve the kinetics and stability of cathodes are also dissected, followed by the evaluation of the application prospects and modifications between various anodes and the strategies of electrolyte design including cosolvent, blended Li salts, high-concentration electrolyte, and additive introduction. Such designs elucidate the successful exploration of low-temperature LIBs with high energy density and long lifespan. This review prospects the future paths of research for LIBs under cold environments, aiming to provide insightful guidance for the reasonable design of LIBs under low temperature, accelerating their widespread application and commercialization. [ABSTRACT FROM AUTHOR]

By virtue of its high specific surface area and low tortuosity for ionic storage and transportation, holey graphene has come to be regarded as a promising material for energy storage devices, such as lithium ion batteries, and supercapacitors. For practical applications, a scalable and green preparation method for holey graphene is required. This work proposes a facile preparation method for holey graphene by simply microwaving pristine graphene in air. Compared with previous scalable methods, this method exhibits much greater efficiency, reducing the preparation time from hours to minutes. The mechanism underlying the microwave irradiation-induced formation of nanosized holes involves the interaction between microwaves, electrons, oxygen in air, and carbon atoms in the defect areas of the graphene. The size, density, and distribution of holes can be controlled by tuning the microwave irradiation time and oxygen concentration. Used as a hybrid conductive agent, the as-prepared holey multilayer graphene increases capacitance retention to 96.25% at high current density (8 A g−1), and 96.48% in long cycles (1 A g−1 and 10 000 cycles). [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO2) is a promising anode for lithium‐ion batteries (LIBs) due to its long lifespan and high rate capability, arising from its excellent structural stability upon lithium intercalation‐deintercalation, but suffers from low conductivity and diffusivity. In contrast, germanium (Ge) possesses high specific theoretical capacity (1600 mA h g−1) as well as high electrical conductivity and high Li+ diffusivity, but the large volume changes upon cycling and the high price still impede its practical application. Herein, with the objective to overcome the drawbacks of TiO2‐based anode materials, Ge/TiO2@C nanotablets with a small amount of Ge content are successfully prepared by annealing C4H12GeO4/MIL‐125 mixtures in Ar/H2 atmosphere. Benefiting from the well‐dispersion of Ge nanoparticles within the TiO2@C matrices, the composites exhibit superior electrochemical performance when examined as a LIB anode material, delivering high reversible capacities of 502/258 mA h g−1 after 200/500 cycles at current densities of 200/500 mA g−1, respectively. Notably, the Ge/TiO2@C shows enhanced surface/pore features and demonstrates improved conductivity, lithium diffusion and specific capacities, owing to the introduction of Ge component. [ABSTRACT FROM AUTHOR]

Conventional bulky and rigid power systems are incapable of meeting flexibility and breathability requirements for wearable applications. Despite the tremendous efforts dedicated to developing various 1D energy storage devices with sufficient flexibility, challenges remain pertaining to fabrication scalability, cost, and efficiency. Here, a scalable, low-cost, and high-efficiency 3D printing technology is applied to fabricate a flexible all-fiber lithium-ion battery (LIB). Highly viscous polymer inks containing carbon nanotubes and either lithium iron phosphate (LFP) or lithium titanium oxide (LTO) are used to print LFP fiber cathodes and LTO fiber anodes, respectively. Both fiber electrodes demonstrate good flexibility and high electrochemical performance in half-cell configurations. All-fiber LIB can be successfully assembled by twisting the as-printed LFP and LTO fibers together with gel polymer as the quasi-solid electrolyte. The all-fiber device exhibits a high specific capacity of ≈110 mAh g−1 at a current density of 50 mA g−1 and maintains a good flexibility of the fiber electrodes, which can be potentially integrated into textile fabrics for future wearable electronic applications. [ABSTRACT FROM AUTHOR]

Microfibers with conductivity of 649 ± 60 S/cm are introduced through a carbonization of well-aligned graphene oxide (GO) - nanofibrillated cellulose (NFC) hybrid fibers. GO acts as a template for NFC carbonization, which changes the morphology of carbonized NFC from microspheres to sheets while improving the carbonization of NFC. Meanwhile, the carbonized NFC repairs the defects of reduced GO (rGO) and links rGO sheets together. The GO templated carbonization of NFC as well as the alignment of the building blocks along the fiber direction leads to excellent conductivity. Conductive microfibers are evaluated as lithium ion battery anodes, which can be applied in wearable electronics. This approach to make conductive microfibers and the low cost raw materials used in this work may be applied to other carbon based conductive structures. [ABSTRACT FROM AUTHOR]

Improving battery capacity and power is a daunting challenge,and in Li-ion batteries positive electrodes often set the limitationon both properties. Layered transition-metal oxides have served asthe mainstream cathode materials for high-energy batteries due totheir large theoretical capacity (∼280 mAh/g). Here we reporta significant enhancement of cathode capacity utilization througha novel concept of material design. By embedding Li(Ni0.5Co0.2Mn0.3)O2in the single wallcarbon nanotube (CNT) network, we created a composite in which allcomponents are electrochemically active. Long-term charge/dischargestability was obtained between 3.0 and 4.8 V, and both Li(Ni0.5Co0.2Mn0.3)O2and CNT contributeto the overall reversible capacity by 250 and 50 mAh/g, respectively.The observed improvement causes significant depolarization withinthe electrodes through the CNT network system. Additionally, the depolarizationprovides the ideal template to understand the solid reaction mechanismof Li(Ni0.5Co0.2Mn0.3)O2by demonstrating well-defined two-stage delithiation kinetics consistentwith first-principle calculations, which would be otherwise impossible.These results deliver new insights on both practical designs and fundamentalunderstandings of battery cathodes. [ABSTRACT FROM AUTHOR]

Nanostructured ternary/mixed transition metal oxides have attracted considerable attentions because of their high‐capacity and high‐rate capability in the electrochemical energy storage applications, but facile large‐scale fabrication with desired nanostructures still remains a great challenge. To overcome this, a facile synthesis of porous NiCoO2 nanofibers composed of interconnected nanoparticles via an electrospinning–annealing strategy is reported herein. When examined as anode materials for lithium‐ion batteries, the as‐prepared porous NiCoO2 nanofibers demonstrate superior lithium storage properties, delivering a high discharge capacity of 945 mA h g−1 after 140 cycles at 100 mA g−1 and a high rate capacity of 523 mA h g−1 at 2000 mA g−1. This excellent electrochemical performance could be ascribed to the novel hierarchical nanoparticle‐nanofiber assembly structure, which can not only buffer the volumetric changes upon lithiation/delithiation processes but also provide enlarged surface sites for lithium storage and facilitate the charge/electrolyte diffusion. Notably, a facile synthetic strategy for fabrication of ternary/mixed metal oxides with 1D nanostructures, which is promising for energy‐related applications, is provided. [ABSTRACT FROM AUTHOR]

A 3D fiber-network-reinforced PEO-based composite polymer electrolyte for high-temperature lithium metal batteries is prepared with a polyimide framework and trimethyl phosphate plasticizer. It works stably in a wide working temperature range from 40 to 140 °C. Remarkably, the LiFePO 4 /Li cell with the composite electrolyte performs stably for over 300 cycles at 120 °C and it can still survive 80 cycles at 140 °C. [Display omitted] Traditional liquid lithium-ion batteries are not applicable for extreme temperatures, due to the shrinkage of separators and volatility of electrolytes. It is necessary to develop advanced electrolytes with desirable characteristics in terms of thermal stability, electrochemical stability and mechanical properties. Solid-state electrolytes, such as polyethylene oxide (PEO), outperform other types and bring the opportunity to realize the high-temperature lithium-ion batteries. However, the softness of PEO at elevated temperatures leads to battery failure. In this work, a three-dimensional fiber-network-reinforced PEO-based composite polymer electrolyte is prepared. The introduced polyimide (PI) framework and trimethyl phosphate (TMP) plasticizer decrease the crystallinity of PEO and increase the ionic conductivity at 30 °C from 8.79 × 10−6 S cm−1 to 4.70 × 10−5 S cm−1. In addition, the PEO bonds tightly with PI fiber network, improving both the mechanical strength and thermal stability of the prepared electrolyte. With the above strategies, the working temperature range of the PEO-based electrolytes is greatly expanded. The LiFePO 4 /Li cell assembled with the PI-PEO-TMP electrolyte stably performs over 300 cycles at 120 °C. Even at 140 °C, the cell still survives 80 cycles. These excellent performances demonstrate the potential application of the PI-PEO-TMP electrolyte in developing safe and high-temperature lithium batteries. [ABSTRACT FROM AUTHOR]

An atomic layer deposition (ALD) of aluminum-doped zinc oxide (AZO) onto MoO 3 nanorods (denoted as MoO 3 @AZO) was developed to enhance the lithium storage performance of MoO 3 anode. Thanks to the highly conductive and robust AZO layer, the MoO 3 @AZO electrode demonstrated high pseudocapacitive contribution (76.2 % at 1.0 mV s −1), enhanced electron/ion transferability, outstanding rate performance (708 mAh g −1 at 2 A g −1) and excellent cycling stability (973 mAh g −1 after 100 cycles at 0.2 A g −1 with a high capacity retention of 92.8 %) when applied as an anode for lithium-ion batteries. Ex-situ transmission electron microscopy analysis revealed that the rod feature of MoO 3 @AZO was well retained with the protection of the AZO layer even after 100 cycles. Moreover, the ALD-AZO coating may also be commonly used for other metal oxides to enhance their electron conductivity and structural stability. [Display omitted] [ABSTRACT FROM AUTHOR]

CoMoO 4 nanoparticles have been successfully in-situ formed and simultaneously embedded within the porous carbon nanofibers (CoMoO 4 /CNFs) via a facile electrospinning-annealing strategy. The porous CoMoO 4 /CNFs exhibit a specific surface area of 255.3 m2/g and a pore volume of 0.52 cc/g with average pore diameter of 43.5 nm. The carbon content in the CoMoO 4 /CNFs can be readily controlled by adjusting the annealing temperature. When examined as anode materials for lithium ion batteries (LIBs), the CoMoO 4 /CNFs demonstrate superior electrochemical performance, delivering a high reversible capacity of 802 mA h/g after 200 cycles at 200 mA/g and a high-rate capacity of 574 mA h/g at 2000 mA/g. The excellent lithium storage behavior can be attributed to the incorporation of CoMoO 4 nanoparticles into the porous N -doped graphitic carbon nanofibers, which efficiently buffer the volume changes of CoMoO 4 upon lithiation/delithiation and maintain the overall electrode conductivity/integrity. [ABSTRACT FROM AUTHOR]

We report an amorphorization-hybridization strategy to enhance lithium storage by casting atomically mixed amorphorized SnO 2 /MoO 3 into porous foam-like carbon nanoflakes (denote as SnO 2 /MoO 3 @CNFs, or SMC in short), which are simply prepared by annealing tin(II)/molybdenum(IV) 2-ethylhexanoate within CNFs under ambient atmosphere at a low temperature (300 °C). The SnO 2 /MoO 3 loading amount within CNFs can be easily adjusted by controlling the Sn/Mo/C precursors. When examined as lithium ion battery (LIB) anode materials, the amorphorized SnO 2 /MoO 3 @CNFs with carbon content of 32 wt% (also denote as SMC-32, in which the number represents the carbon content) deliver a high reversible capacity of 1120.5 mA h/g after 200 cycles at 200 mA/g and then 651.5 mA h/g after another 300 cycles at 2000 mA/g, which is much better than that of the crystalline SnO 2 /CNFs (carbon content of 34 wt%), MoO 3 /CNFs (carbon content of 22.7 wt%), or SnO 2 /MoO 3 @CNFs (with lower carbon contents of 11 and 25 wt%). The electrochemical measurements as well as the ex situ structure characterization clearly suggest that combination of amorphorization and hybridization of SnO 2 /MoO 3 with CNFs synergistically contributes to the superior lithium storage performance with high pseudocapacitive contribution. [ABSTRACT FROM AUTHOR]

Designing solid-state lithium metal batteries requires fast lithium-ion conductors, good electrochemical stability, and scalable processing approaches to device integration. In this work, we demonstrate a unique design for a flexible lithium-ion conducting ceramic textile with the above features for use in solid-state batteries. The ceramic textile was based on the garnet-type conductor Li 7 La 3 Zr 2 O 12 and exhibited a range of desirable chemical and structural properties, including: lithium-ion conducting cubic structure, low density, multi-scale porosity, high surface area/volume ratio, and good flexibility. The solid garnet textile enabled reinforcement of a solid polymer electrolyte to achieve high lithium-ion conductivity and stable long-term Li cycling over 500 h without failure. The textile also provided an electrolyte framework when designing a 3D electrode to realize ultrahigh cathode loading (10.8 g/cm 2 sulfur) for high-performance Li-metal batteries. [ABSTRACT FROM AUTHOR]

The safety issue of lithium ion batteries has always received extensive attention and become the main obstacle restricting their development and applications. Commercial polyolefin separators own poor thermal stability, which cannot ensure the safe operation of lithium ion batteries after heating. Herein, an electrolyte-locked thermally stable composite separator polyimide/poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP@PI) is constructed through coating a layer of PVDF-HFP on the electrospun PI fibers membrane. In this structure, the high electrolyte retention ability and excellent thermal dimensional stability of PVDF-HFP@PI effectively inhibit the continuous reaction between electrolyte and Li anode, and prevent the battery failure after heating. In addition, the prepared PVDF-HFP@PI has good mechanical properties and high ionic conductivity of up to 1.79 mS cm−1, which significantly improves the electrochemical performance of the batteries. Therefore, the pouch cell with PVDF-HFP@PI retains 77.4 % of the original capacity after 300 cycles at 0.1 C. More importantly, the cell with PVDF-HFP@PI can work normally after heated under 140 °C for 1 h, exhibiting high heat tolerance. • PI has good thermal stability. It can improve the safety at high temperatures. • PVDF-HFP enhances the structural stability and mechanical properties of PVDF-HFP@PI and inhibits the growth of Li dendrite. • PVDF-HFP@PI with good electrolyte retention ability can inhibit the continuous reaction between electrolyte and Li anode. [ABSTRACT FROM AUTHOR]