Rigid-flexible coupling network solid polymer electrolytes for all-solid-state lithium metal batteries.

Poor mechanical strength at working temperature and low ionic conductivity seriously hinder the application of poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) in high performance all-solid-state lithium metal batteries (LMBs). Here, we design and prepare a series of rigid-flexible coupling network SPEs (RFN-SPEs) with soft poly(ethylene glycol) (PEG) chains and rigid crosslinkers containing the benzene structure. Compared with soft crosslinkers, rigid crosslinkers provide the same amount of active crosslinking points with smaller molecular weight, and meanwhile enhance the mechanical strength of the network. Therefore, based on the rigid crosslinkers, RFN-SPEs exhibit synchronously improved ionic conductivity and mechanical strength. With these RFN-SPEs, symmetrical cells can be cycled for over 2100 h at 0.5 mA cm-2. Meanwhile, stable cycling and high-rate capability could be achieved for LMBs, revealing that SPEs with the rigid-flexible coupling network are promising electrolyte systems for all-solid-state LMBs.

Zn-In Alloying Powder Solvent Free Electrode Toward High-Load Ampere-Hour Aqueous Zn-Mn Secondary Batteries.

Aqueous Zn-ion batteries (ZIBs) are promising candidates for large-scale energy storage due to high safety, abundant reserves, low-cost, and high energy density. However, the reversibility of the metallic Zn anode in the mild electrolyte is still unsatisfactory, due to the Zn dendrite growth, hydrogen evolution, and corrosion passivation. Herein, a Zn-In alloying powder solvent free electrode is proposed to replace the Zn foil in ZIBs. The novel Zn anodes are constructed by a solvent-free manufacturing process with carbons, forming a 3D Zn deposition network and providing uniformly electric field distribution. The In on the Zn powder surface can increase the overpotential for hydrogen evolution and further improve the morphology of Zn deposition against dendrite growth. The Zn solvent-free electrodes enable the Zn-MnO2 batteries with high cathode loading mass of 10-20 mg cm-2 to achieve >380 stable cycles. Furthermore, the assembled soft package batteries of 2.4 Ah (52 Wh kg-2 ) is evaluated and the capacity retention is maintained at 80% after 200 cycles at a high areal capacity of 5 mAh cm-2 without gas evolution. This work offers a workable strategy to develop a durable Zn anode for the eventually commercial applications of aqueous Zn-Mn secondary batteries.

Polyphenylene Sulfide-Based Solid-State Separator for Limited Li Metal Battery.

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 anions, increasing the Li+ transference number to 0.8-0.9, and widening the electrochemical potential window (EPW > 5.1 V). At 25 °C, the PPS-SSS exhibits high intrinsic Li+ diffusion coefficient and ionic conductivity (>10-4 S cm-1 ), and Li+ transport rectifying effect, resulting in homogenous Li-plating on Cu at 2 mA cm-2 density. Based on the limited Li-plated Cu anode or anode-free Cu, high loadings cathode and high voltage, the Li-metal batteries (LMBs) with polyethylene (PE) protected PPS-SSSs deliver high energy and power densities (>1000 Wh L-1 and 900 W L-1 ) with >200 cycling life and high safety, exceeding those of state-of-the-art Li-ion batteries. The results promote the Li metal battery toward practicality.

Boosting Specific Energy and Power of Carbon-Ionic Liquid Supercapacitors by Engineering Carbon Pore Structures.

Carbon-ionic liquid (C-IL) supercapacitors (SCs) promise to provide high capacitance and high operating voltage, and thus high specific energy. It is still highly demanding to enhance the capacitance in order to achieve high power and energy density. We synthesized a high-pore-volume and specific-surface-area activated carbon material with a slit mesoporous structure by two-step processes of carbonization and the activation from polypyrrole. The novel slit-pore-structured carbon materials provide a specific capacity of 310 F g-1 at 0.5 A g-1 for C-IL SCs, which is among one of the highest recorded specific capacitances. The slit mesoporous activated carbons have a maximum ion volume utilization of 74%, which effectively enhances ion storage, and a better interaction with ions in ionic liquid electrolyte, thus providing superior capacitance. We believe that this work provides a new strategy of engineering pore structure to enhance specific capacitance and rate performance of C-IL SCs.

Great Enhancement of Carbon Energy Storage through Narrow Pores and Hydrogen-Containing Functional Groups for Aqueous Zn-Ion Hybrid Supercapacitor.

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.

Preparation and Optimization of New High-Power Nanoscale Li4Ti5O12 Full-Cell System.

Lithium ion batteries with graphite negative electrodes have been developed to date due to their low power density, which limits their application in many cases, however. Nanoscale Li4Ti5O12 has higher power density than conventional graphite anode materials. In order to ensure that the full-cell system has high power and high energy, cathode materials are very important. In this paper, three different cathode materials, LiNi0.8Co0.15Al0.05O2 (NCA), LiNi0.6Co0.2Mn0.2O2 (NCM622), and LiCoO2 (LCO), were used to conduct a comprehensive study, and optimal NCA-Li4Ti5O12(LTO) full battery system was selected under high power conditions. On the basis, in order to further increase battery power density, and in combination with the mechanism of the supercapacitor non-Faradic energy storage, polyaniline activated carbon material (PANI-AC) with excellent capacitance characteristics was prepared. In the end, we proposed a new type of hybrid battery capacitor system with high power and high energy.