An increase of the Zn-ion hybrid SC performance by carbon surface chemistry through the pseudocapacitance induced by proton transfer.

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The proton transfer mechanism on the carbon cathode surface has been considered as an effective way to boost the electrochemical performance of Zn-ion hybrid supercapacitors (SCs) with both ionic liquid and organic electrolytes. However, cheaper, potentially safer, and more environmental friendly supercapacitor can be achieved by using aqueous electrolyte. Herein, we introduce the proton transfer mechanism into a Zn-ion hybrid supercapacitor with the ZnSO4 aqueous electrolyte and functionalized activated carbon cathode materials (FACs). We reveal both experimentally and theoretically an enhanced performance by controlling the micropores structure and hydrogen-containing functional groups (–OH and –NH functions) of the activated carbon materials. The Zn-ion SCs with FACs exhibit a high capacitance of 435 F g−1 and good stability with 89% capacity retention over 10,000 cycles. Moreover, the proton transfer effect can be further enhanced by introducing extra hydrogen ions in the electrolyte with low pH value. The highest capacitance of 544 F g−1 is obtained at pH = 3. The proton transfer process tends to take place preferentially on the hydroxyl-groups based on the density functional theory (DFT) calculation. The results would help to develop carbon materials for cheaper and safer Zn-ion hybrid SCs with higher energy.

Lithium difluoro(axalato)borate (LiODFB) was synthesized in dimethyl carbonate (DMC) solvent and purified by the method of solventing-out crystallization. The structure characterization of the purified LiODFB was performed by Fourier transform infrared (FTIR) spectrometry and nuclear magnetic resonance (NMR) spectrometry. The electrochemical properties of the cells using 1 mol/L LiPF 6 and 1 mol/L LiODFB in ethylene carbonate (EC)/DMC were investigated, respectively. The results indicate that LiODFB can be reduced at about 1.5 V and form a robust protective solid electrolyte interface (SEI) film on the graphite surface in the first cycle. The graphite/LiNi 1/3 Mn 1/3 Co 1/3 O 2 cells with LiODFB-based electrolyte have very good capacity retention at 55 , ℃ and show very good rate capability at 0.5C and 1C charge/discharge rate. Therefore, as a new salt, LiODFB is a most promising alternative lithium salt to replace LiPF 6 for lithium ion battery electrolytes in the future.

Supercabatteries, combining the energy of secondary batteries with the power of supercapacitors, have attracted significant attention in the energy storage research and market field. Herein, we continued our previous 3D electrode works and fabricated supercabatteries with the prelithiated ACNTs@MnOx positive and C/MnOy/ACNTs negative electrodes, which can offer ultrahigh discharge capacities and remarkable improved capabilities and stabilities. The theoretical specific capacities of the supercabatteries were calculated and predicted as function of the P/N mass ratios and initial potentials for the two electrodes, based on the half-cell results. The experimental specific capacities of the supercabatteries with different P/N mass ratios and charge injection pretreatments matched well with the prediction line. The supercabattery with a P/N mass ratio of 1.6 and optimized EPW delivered the maximum specific discharge capacity of 217 mAh g−1 and energy density of 208.6 Wh kg−1 based on the active materials. The supercabattery remained at 105.8 Wh kg−1 with a ultrahigh power density of 3000 W kg−1 and maintained 80% of the initial capacity after 1000 cycles.

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shortages put forward serious challenges to modern energy storage methods. [1] Under such circumstances, lithium-ion batteries (LIBs) have become more and more widely used in energy storage due to their advantages of high energy density and cycle life. [2] However, conventional LIBs usually use a large amount of flammable, explosive, and volatile organic liquid electrolytes, leading to serious safety problems in use. [3] Moreover, the state-of-the-art LIBs are insatiable in the rising demand for higher energy density. Advanced LIBs based on Li metal anodes (LMBs) could provide higher energy density and become a hot research topic. [4] But the "dead" Li and poor cycling caused by uncontrolled growth of Li dendrites also limit the development of the LMBs.By using solid-state electrolytes (SSE) instead of traditional organic liquid electrolytes, solid-state LMBs are considered to be the most promising energy storage method. SSEs can suppress Li dendrites' formation, thereby fundamentally solving the safety and cycling issues of LMBs. [5] To achieve safe, high energy and power density and better cycle stability, the SSEs require a high diffusion rate including bulk and interface in a wide temperature range, thin and flexible electrolyte films, chemical and mechanical stabilities. However, the SSEs reported so far remain formidable challenges to meet all the above requirements. In general, SSEs can be divided into two categories: inorganic glassy or ceramic electrolytes and solid polymer electrolytes (SPEs). For instance, the inorganic solid electrolyte systems, including the garnet-type and perovskite-type ceramic materials and sulfide-type glass, have been extensively studied for the high conductivity. However, due to the brittle nature, poor processing performance, high interface resistance with the electrode, and high sensitivity to moisture for sulfides, they are still not suitable for wide commercial applications. [6] Various organic SPEs, such as the most studied polyethylene oxide (PEO), [7] the polyacrylonitrile (PAN), [8] the poly(vinylidene fluoride) (PVDF), [9] the polymethyl methacrylate (PMMA), [10] and the polypropylene oxide (PPO), [11] have improved thermal stability and flexibility. Still, their low ionic conductivities restrict the high-power operation of the battery at room temperature. One of the approaches to address above mentioned challenges is to use quasi-solid route by adding the liquid electrolytes (organic solvents or ionic liquid)The urgent need for high energy batteries is pushing the battery studies toward the Li metal and solid-state direction, and the most central question is finding proper solid-state electrolyte (SSE). So far, the recently studied electrolytes have obvious advantages and fatal weaknesses, resulting in indecisive plans for industrial production. In this work, a thin and dense lithiated polyphenylene sulfide-based solid state separator (PPS-SSS) prepared by a solvent-free process in pilot stage is proposed. Moreover, the PPS surface is functionalized to immobilize the...

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