Electrode materials with three-dimensional (3D) mesoporous structures possess superior features, such as shortened solid-phase lithium diffusion distance, large pore volume, full lithium ion accessibility, and a high specific area, which can facilitate fast lithium ion transport and electron transfer between solid/electrolyte interfaces. In this work, we introduce a facile synthesis route for the preparation of a 3D nanoarchitecture of Ge coated with carbon (3D-Ge/C) via a carbothermal reduction method in an inert atmosphere. The 3D-Ge/C showed excellent cyclability: almost 86.8% capacity retention, corresponding to a charge capacity of 1216 mAh g -1 even after 1000 cycles at a 2 C-rate. Surprisingly, the high average reversible capacity of 1122 mAh g -1 was maintained at a high charge rate of 100 C (160 A g -1 ). Even at an ultrahigh charge rate of 400 C (640 A g -1 ), an average capacity of 429 mAh g -1 was attained. Further, the full cell composed of 3D-Ge/C anode and LiCoO2 cathode exhibited excellent rate capability and cyclability with 94.7% capacity retention over 50 cycles. 3D-Ge/C, which offers a high energy density like batteries as well as a high power density like supercapacitors, is expected to be used in a wide range of electrochemical devices.A novel, facile synthetic route has been proposed to prepare a 3D nanoarchitecture Ge coated with carbon (3D-Ge/C) via a carbothermal reduction. The GeO 2 /PVP composite was carbonized in an argon atmosphere at 775 °C for 1 h to carbonize the PVP. During carbonization, the carbothermal reduction of GeO 2 occurred and simultaneously formed Ge within a 3D structure.

A composite gel polymer electrolyte (CGPE) based on poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) polymer that includes Al-doped Li0.33La0.56TiO3 (A-LLTO) particles covered with a modified SiO2 (m-SiO2) layer was fabricated through a simple solution-casting method followed by activation in a liquid electrolyte. The obtained CGPE possessed high ionic conductivity, a large electrochemical stability window, and interfacial stability-all superior to that of the pure gel polymer electrolyte (GPE). In addition, under a highly polarized condition, the CGPE effectively suppressed the growth of Li dendrites due to the improved hardness of the GPE by the addition of inorganic A-LLTO/m-SiO2 particles. Accordingly, the Li-ion polymer and Li-O2 cells employing the CGPE exhibited remarkably improved cyclability compared to cells without CGPE. In particular, the CGPE as a protection layer for the Li metal electrode in a Li-O2 cell was effective in blocking the contamination of the Li electrode by oxygen gas or impurities diffused from the cathode side while suppressing the Li dendrites.

Germanium (Ge) possesses a great potential as a high‐capacity anode material for lithium ion batteries but suffers from its poor capacity retention and rate capability due to significant volume expansion by lithiation. Here, a facile synthetic route is introduced for producing nanometer‐sized Ge crystallites interconnected by carbon (GEC) via thermal decomposition of a Ge‐citrate complex followed by a calcination process in an inert atmosphere. The GEC electrode shows outstanding electrochemical performance, i.e., an almost 98.8% capacity retention of 1232 mAh g−1, even after 1000 cycles at the rate of C/2. Importantly, a high discharge capacity of 880 mAh g−1 is maintained at the very high rate of 10 C. The excellent anode performance of GEC stems from both effective buffering of carbon anchored to the Ge nanocrystals and the high open porosity of the GEC aggregated powder with an average pore diameter of 32 nm. Furthermore, the interfacial layer formed between Ge and carbon plays an essential role in prolonging the cycle life. The GEC electrode can be successfully employed as an anode for next generation lithium ion batteries.

In this study, a novel method has been proposed for synthesizing amorphous GeO2/C composites. The amorphous GeO2/C composite without carbon black as an electrode for Li-ion batteries exhibited a high specific capacity of 914 mA h g(-1) at the rate of C/2 and enhanced rate capability. The amorphous GeO2/C electrode exhibited excellent electrochemical stability with a 95.3% charge capacity retention after 400 charge-discharge cycles, even at a high current charge-discharge of C/2. Furthermore, a full cell employing the GeO2/C anode and the LiCoO2 cathode displayed outstanding cycling performance. The superior performance of the GeO2/C electrode enables the amorphous GeO2/C to be a potential anode material for secondary Li-ion batteries.

Here, we propose a simple method for direct synthesis of a Si@SiC composite derived from a SiO@C precursor via a Mg thermal reduction method as an anode material for Li-ion batteries. Owing to the extremely high exothermic reaction between SiO and Mg, along with the presence of carbon, SiC can be spontaneously produced with the formation of Si. The synthesized Si@SiC was composed of well-mixed SiC and Si nanocrystallites. The SiC content of the Si@SiC was adjusted by tuning the carbon content of the precursor. Among the resultant Si@SiC materials, the Si@SiC-0.5 sample, which was produced from a precursor containing 4.37 wt % of carbon, exhibits excellent electrochemical characteristics, such as a high first discharge capacity of 1642 mAh g and 53.9% capacity retention following 200 cycles at a rate of 0.1C. Even at a high rate of 10C, a high reversible capacity of 454 mAh g was obtained. Surprisingly, at a fixed discharge rate of C/20, the Si@SiC-0.5 electrode delivered a high capacity of 989 mAh g at a charge rate of 20C. In addition, a full cell fabricated by coupling a lithiated Si@SiC-0.5 anode and a LiCoO cathode exhibits excellent cyclability over 50 cycles. This outstanding electrochemical performance of Si@SiC-0.5 is attributed to the SiC phase, which acts as a buffer layer that stabilizes the nanostructure of the Si active phase and enhances the electrical conductivity of the electrode.