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Micro-sized silicon anodes can significantly increase the energy density of lithium-ion batteries with low cost. However, the large silicon volume changes during cycling cause cracks for both organic-inorganic interphases and silicon particles. The liquid electrolytes further penetrate the cracked silicon particles and reform the interphases, resulting in huge electrode swelling and quick capacity decay. Here we resolve these challenges by designing a high-voltage electrolyte that forms silicon-phobic interphases with weak bonding to lithium-silicon alloys. The designed electrolyte enables micro-sized silicon anodes (5 µm, 4.1 mAh cm−2) to achieve a Coulombic efficiency of 99.8% and capacity of 2175 mAh g−1 for >250 cycles and enable 100 mAh LiNi0.8Co0.15Al0.05O2 pouch full cells to deliver a high capacity of 172 mAh g−1 for 120 cycles with Coulombic efficiency of >99.9%. The high-voltage electrolytes that are capable of forming silicon-phobic interphases pave new ways for the commercialization of lithium-ion batteries using micro-sized silicon anodes. Micro-sized silicon are promising anode materials due to low-cost and high-energy, yet their application is hindered by inaccessible electrolytes. Here, the authors report sulfolane-based electrolytes that form silicon-phobic interphases and enable high-voltage pouch cells to achieve superior cycle life. [ABSTRACT FROM AUTHOR]

Synthesis of silicon/carbon (Si/C) composites from biomass resources could enable the effective utilization of agricultural products in the battery industry with economical as well as environmental benefits. Herein, a simplified process was developed to synthesize Si/C from biomass, by using a low‐cost agricultural byproduct "rice husk (RH)" as a model. This process includes the calcination of RH for SiO2/C and the reduction of SiO2/C by Al in molten salts at a moderate temperature. This process does not need the removal of carbon before thermal reduction of SiO2, which is thought to be necessary to avoid the formation of SiC at elevated temperatures. Thus, carbon derived from biomass can be directly used for Si/C composites for anode materials. The resultant Si/C shows a high reversible capacity of 1309 mAh g−1 and long cycle life (300 cycles). This research advocates a new and simplified strategy for the synthesis of RH‐based biomass‐derived Si/C, which is beneficial for low‐cost, environmentally friendly, and green energy storage applications. [ABSTRACT FROM AUTHOR]

A new super-concentrated aqueous electrolyte is proposed by introducing a second lithium salt. The resultant ultra-high concentration of 28 m led to more effective formation of a protective interphase on the anode along with further suppression of water activities at both anode and cathode surfaces. The improved electrochemical stability allows the use of TiO2 as the anode material, and a 2.5 V aqueous Li-ion cell based on LiMn2O4 and carbon-coated TiO2 delivered the unprecedented energy density of 100 Wh kg−1 for rechargeable aqueous Li-ion cells, along with excellent cycling stability and high coulombic efficiency. It has been demonstrated that the introduction of a second salts into the 'water-in-salt' electrolyte further pushed the energy densities of aqueous Li-ion cells closer to those of the state-of-the-art Li-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: Well dispersed chestnut-like Cd2Ge2O6 (CGO) and Cd2Ge2O6/reduced graphene oxide (CGO/RGO) nanocomposites are successfully prepared via a facile one-pot hydrothermal method and characterized as novel lithium storage materials for the first time. Electrochemical characterization of lithiation/delithiation of the CGO/RGO nanocomposites reveals a large capacity of 943mAhg−1 for the first cycle and a capacity retention of 721mAhg−1 even after 100 cycles. The superior electrochemical performance of the CGO/RGO nanocomposites electrode compared to the pure CGO electrode can be attributed to the well dispersed RGO which enhances the electronic conductivity and accommodate the volume change during the lithium storage process. [Copyright &y& Elsevier]

A novel bismuth-carbon composite, in which bismuth nanoparticles were anchored in a nitrogen-doped carbon matrix (Bi@NC), is proposed as anode for high volumetric energy density lithium ion batteries (LIBs). Bi@NC composite was synthesized via carbonization of Zn-containing zeolitic imidazolate (ZIF-8) and replacement of Zn with Bi, resulting in the N-doped carbon that was hierarchically porous and anchored with Bi nanoparticles. The matrix provides a highly electronic conductive network that facilitates the lithiation/delithiation of Bi. Additionally, it restrains aggregation of Bi nanoparticles and serves as a buffer layer to alleviate the mechanical strain of Bi nanoparticles upon Li insertion/extraction. With these contributions, Bi@NC exhibits excellent cycling stability and rate capacity compared to bare Bi nanoparticles or their simple composites with carbon. This study provides a new approach for fabricating high volumetric energy density LIBs. [ABSTRACT FROM AUTHOR]

• Li 3 VO 4 nanoparticles in porous N-doped carbon are synthesized. • Porous N-doped carbon is derived from melamine and citric acid. • Porous N-doped carbon and Li 3 VO 4 nanoparticles together give superior performances. • This composite exhibits a capacity of 236.6 mAh g−1 after 1000 cycles at 4.0 A g−1. • This composite coupled with LiCoO 2 as full cells are examined. Li 3 VO 4 nanoparticles in N-doped carbon with porous structure are synthesized using supermolecular aggregates formed by melamine and citric acid as the nitrogen source, via a dry-freezing process, followed with a calcination. Nitrogen doping enhances the interaction between Li 3 VO 4 and carbon, reduces the charge-transfer resistance over the interface, and restrains the pulverization and aggregation upon cycling. The design of porous structure accelerates the permeation of electrolyte and increases the contact between active materials and electrolyte. The synergistic effects between N-doped carbon and porous structure significantly improve the electrochemical performances. Thus, this composite delivers a capacity of 405.1 mAh g−1 at 0.1 A g−1 or 199.9 mAh g−1 at 10.0 A g−1 within 0.2–3.0 V. After 1000 cycles at 4.0 A g−1, the specific capacity is still kept as 236.6 mAh g−1. By pairing with commercial LiCoO 2 , this composite delivers a high energy density of 195.05 Wh kg−1 total at 70.52 W kg−1 total , and 94.06 Wh kg−1 total at 3.9 kW kg−1 total. [ABSTRACT FROM AUTHOR]

Abstract: A porous silicon–carbon anode on a lightweight carbon fiber current collector is reported here for lithium-ion batteries. This Si–C anode was synthesized through a one-step carbonization of a Si-poly(acrylonitrile-co-methyl acrylate) precursor, which was directly deposited on a carbon fiber mat. The carbon fiber curent collector allows higher loading of active materials, resulting in high energy to mass and area ratios. The obtained Si–C electrode demonstrated superior overall capacity, cyclability, and rate capacity. [Copyright &y& Elsevier]

Lithium-ion capacitors, as a hybrid electrochemical energy storage device, realize high specific energy and power density within one device, thus attracting extensive attention. Here, hierarchically porous Li 3 VO 4 /C nanocomposite is prepared by a solvo-thermal reaction, followed with a post-annealing process. This composite has macropores at the center and mesopores in the wall, thus effectively promoting electrolyte penetration and structure stability upon cycling simultaneously. Compared to mesoporous Li 3 VO 4 , the enhanced rate capability and specific capacity of hierarchically porous Li 3 VO 4 /C indicate the synergistic effect of mesopores and macropores. Inspired by these results, this composite is coupled with mesoporous carbon (CMK-3) for lithium-ion capacitors, generating a specific energy density of 105 Wh kg −1 at a power density of 188 W kg −1 . Even if the power density increases to 9.3 kW kg −1 , the energy density still remains 62 Wh kg −1 . All these results demonstrate the promising potential of hierarchically porous Li 3 VO 4 in lithium ion capacitors. [ABSTRACT FROM AUTHOR]

Nano-Sn/C composites are ideal anode materials for highenergyand power density Li-ion batteries. However, because of the low meltingpoint of Sn and the tendency of grain growth, especially during hightemperature carbonization, it has been a significant challenge tocreate well-dispersed ultrasmall Sn nanoparticles within a carbonmatrix. In this paper, we demonstrate an aerosol spray pyrolysis technique,as a facile and scalable method, to synthesize a nano-Sn/C compositewith uniformly dispersed 10 nm nano-Sn within a spherical carbon matrix.The discharge capacity of nano-Sn/C composite sphere anodes maintainsthe initial capacity of 710 mAh/g after 130 cycles at 0.25 C. Thenano-Sn/C composite sphere anodes can provide ∼600 mAh/g evenat a high rate of 20 C. To the best of our knowledge, such high rateperformance for Sn anodes has not been reported previously. The exceptionalperformance of the nano-Sn/C composite is attributed to the uniquenano-Sn/C structure: (1) carbon matrix offers mechanical support toaccommodate the stress associated with the large volume change ofnano-Sn, thus alleviating pulverization; (2) the carbon matrix preventsSn nanoparticle agglomeration upon prolonged cycling; and (3) carbonnetwork provides continuous path for Li ions and electrons insidethe nano-Sn/C composite spheres. [ABSTRACT FROM AUTHOR]

Abstract: A patterned 3D Si anode is fabricated by physical vapor deposition of n-type Si on a self-assembled TMV1cys-structured nickel current collector. The combination of the large surface area conferred by the virus-enabled 3D Ni/TMV1cys current collector with the high electric conductivity of n-type Si rods results in excellent cyclic stability and rate capability for the core-shell n-type Si/Ni/TMV1cys anodes. Electrochemical impedance spectroscopy reveals that the high electronic conductivity of n-type Si significantly reduces charge transfer resistance, thus even at high current densities the capacity of the n-type Si is increased to almost 630mAh/g compared to undoped Si. [Copyright &y& Elsevier]

Abstract: The effects of carbonization process and carbon nanofiber/nanotube additives on the cycling stability of silicon–carbon composite anodes were investigated by monitoring the impedance evolution during charge/discharge cycles with electrochemical impedance spectroscopy (EIS). Three types of Si–C anodes were investigated: the first type consisted of Si nanoparticles incorporated into a network of carbon nanofibers (CNFs) and multi-walled carbon nanotubes (MWNTs), with annealed polymer binder. The second type of Si–C anodes was prepared by further heat treatment of the first Si–C anodes to carbonize the polymer binder. The third Si–C anode was as same as the second one except no CNFs and MWNTs being added. Impedance analysis revealed that the carbonization process stabilized the Si–C anode structure and decreased the charge transfer resistance, thus improving the cycling stability. On the other hand, although the MWNTs/CNFs additives could enhance the electronic conductivity of the Si–C anodes, the induced inhomogeneous structure decreased the integrity of the electrode, resulting in a poor long term cycling stability. [Copyright &y& Elsevier]