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A modified gel polymer electrolyte (GPE) with boron nitride (BN) additive was designed to boost the electrochemical performance of rechargeable lithium metal battery, which consists of Li-rich layered cathode and possesses a high energy density. BN, electron insulator and ion conductor, has excellent thermodynamic and electrochemical stability. BN particles were well dispersed in polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) polymer matrices and thus substantially enhanced the electrochemical and physical properties of the GPEs. With only 0.5 wt% BN additive, it remarkably improved the mechanical modulus and ionic conductivity (to 4.1 × 10−4 S∙cm−2) of GPEs, which was beneficial for suppressing lithium dendrite formation and fast ion transportation, respectively, thereby enabling high-performance lithium metal batteries with ultra-long cycle life and high safety at ambient temperature (25 °C) and high temperature (55 °C).

Partially reduced and nitrogen-doped graphene oxides (PRNGs) were prepared through a one-step hydrothermal method with graphene oxide as raw material and phenylethylamine as reducing-doping agents. Benefiting from nitrogen- and oxygen-containing functional groups, interconnected 3D porous networks and high specific surface area, the as-prepared samples demonstrate good electrochemical performances. Particularly, the PRNG-10 electrodes in the wet state show an enhanced gravimetric and volumetric specific capacitance (264.1 F g−1 and 211.3 F cm−3), good rate capability and excellent cycle stability (101.85% of the initial capacitance after 10000 cycles) in 6 M KOH electrolyte.

We fabricate a novel 3D N-doped graphene/silicon composite for lithium-ion battery anodes, with Si nanoparticles uniformly dispersed and thoroughly embedded in the N-doped graphene matrix. The favorable structure of the composite results in a BET surface area and an average mesopore diameter of 189.2 m2 g−1 and 3.82 nm, respectively. The composite delivers reversible capacities as high as 1132 mA h g−1 after 100 cycles under a current of 5 A g−1 and 1017 mA h g−1 after 200 cycles at 1 A g−1, and exhibits an improved rate capability. The present approach shows promise for the preparation of other high-performance anode materials for lithium-ion batteries.

A novel method for scalable fabricating porous silicon/carbon composite as anode material for lithium-ion batteries is reported in this article. Diatomite is used as a raw material for synthesis of porous silicon via combining mechanical ball milling with magnesiothermic reduction method, employing NaCl as a heat scavenger. The resulting silicon maintains the porous structure of diatomite, with large specific surface area of 288.5 m2 g−1 and average pore size of 9.6 nm. The C@pSi-I composite delivers improved cycling stability and good rate capability. A discharge capacity of 1116.7 mA h g−1 at current density of 200 mA g−1 is achieved after 200 cycles, which will be beneficial to the scalable synthesis of porous silicon materials for the next generation lithium-ion batteries.

A Si-rGO/NCT composite, in which Si nanoparticles (SiNPs) are enwrapped with N-doped carbon and combine with N-doped graphene and CNTs as conductive matrices synthesized by simple solution-mixing and carbonization process with pyrolyzing melamine formaldehyde resin (MFR) is developed as a promising candidate anode material for lithium ion batteries (LIBs). The N-doped carbon outside SiNPs can not only improve the electrical conductivity of the composite, but also buffer the stress causing by huge volume change of SiNPs during the lithiation/delithiation process. The Si-rGO/NCT composite exhibits high specific capacity and good cycling stability (892.3 mAh g−1 at 100 mA g−1 up to 100 cycles), as well as improved rate capability. This approach provides a very facile route to obtain silicon-based anode materials.

In this work, the 3D macroscopic graphene hydrogels (MGHs) with a high capacitor performance were easily prepared by a one-step hydrothermal method from graphene oxide (GO) dispersions. A very small amount of 1,4-butanediamine was employed to realize the partial reduction of GO, modification of the 3D structure of MGHs, and nitrogen doping of graphene, at the same time. The synthesized MGH-6 sample in the wet state exhibit a high specific capacitance of 268.8 Fg −1 at 0.3 A g −1 in 6 M KOH electrolyte, and this capacitance can be maintained for 84.9% even as the discharging current density was increased up to 10 A g −1 . The MGH-6 sample also shows good cycle stability along with a 1.03% increase of its initial specific capacitance after 10000 cycles at current density of 10 Ag −1 . These remarkable properties are ascribed to the both nitrogen- and oxygen-containing functional groups, modified macroporous 3D framework, and the high specific surface area of the graphene. Combining with the economical and easy path toward mass production, the present MGH-6 can be expected as a promising candidate for high-performance supercapacitors.

Electrochemical energy devices including batteries, supercapacitors and fuel cells are reliable and practical technologies in which carbon-based electrode materials play critical roles in enhancing performance. Because of this, the source and synthesis of these carbon-based materials have been extensively explored and developed. And of the various carbon-based materials, biomass-derived carbon materials and corresponding composites have been recognized to be capable of delivering high capacities, enhanced rate performances and prolonged cycling stabilities in both lithium-ion batteries and supercapacitors as partially induced through a combination of favorable pore structures and heteroatom-doping. In addition, biomass-derived carbon materials can provide significantly enhanced activity and stability for cathode oxygen reduction reactions if used as catalyst support materials in polymer electrolyte membrane fuel cells. Based on this, this review will provide a comprehensive assessment as well as critical analysis and systematic comparison of biomass-derived carbon materials and corresponding composites as electrode materials in various electrochemical energy devices based on recent progresses in research and development. In addition, related technical challenges are analyzed and possible research directions are proposed to further development for practical application.

Although cation-deficient nanomaterials, especially one-dimensional (1D) nanowires, have demonstrated to be feasible in electrochemical energy storage as promising electrode materials, the effects of cation defects on charge transfer and electrode performance are not fully explored and understood. In this paper, the cation defects are generated in the as-prepared gallium nitride (GaN) via a cost-effective plasma process, serving as the reversible active sites to boost electrochemical performance by simultaneously promoting electrical conductivity and charge transfer. Several techniques, including XRD, TEM, XANES, cyclic voltammetry, Electrochemical impedance spectroscopy, etc., are used to characterize and understand the material morphology, structure and composition as well as the electrochemical properties. Results show that the cation-deficient GaN nanowires have abundant nanochannels, which can facilitate the rapid ionic transfer. The anode of such a material cation can deliver much higher capacities of 746.5 mAh g−1 at 0.1 A g−1 after 100 cycles and 370.2 mAh g−1 at 10 A g−1 after 1000 cycles, respectively. Density functional theory (DFT) calculations prove that benefited from the unique self-supported 1D architecture and cation defects, the local atomic arrangement and electronic structure can be tuned to significantly increase the electrical conductivity and charge transfer efficiency and subsequently boost lithium-ion storage for lithium-ion batteries. This strategy provides an accessible approach to utilize cation-defect nanomaterials for advanced electrochemical energy applications.