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Despite their excellent ionic conductivity and electrochemical oxidative stability, the emerging halide-based solid electrolytes suffer from inherent instability toward Li metal anodes. A thick and resistive interface can be formed by continuous reaction between halide electrolytes and Li anodes, leading to high impedance, low coulombic efficiency, and even short circuit of solid-state cells. Here, we report a thin argyrodite (Li6PS5Cl) protection layer to avoid the direct physical contact of the Li anode with Li3YCl6, a representative halide electrolyte. Li6PS5Cl is kinetically stable towards lithium and can also form a good hetero-contact with Li3YCl6. Highly stable Li plating/stripping cycling of a symmetric cell with a steady overpotential of 100 mV after 1000 h was demonstrated, compared to severe overpotential build-up to reach 1500 mV after 60 h of the control group. Besides, the LiNi0.8Co0.1Mn0.1O2/Li full solid-state cell displayed a high initial coulombic efficiency of >87% and a stable lifetime of over 100 cycles. The facile protection of Li6PS5Cl provides a universal way to prevent unfavorable interaction at the anode interface and realize high performance all-solid-state Li-metal batteries. [ABSTRACT FROM AUTHOR]

Ni-rich layered cathode materials are at the forefront to be deployed in high energy density Li-ion batteries for the automotive market. However, the intrinsic poor structural and interfacial stability during overcharging could trigger violent thermal failure, which severely limits their wide application. To protect the Ni-rich cathode from overcharging, we firstly report a redox-active cation, thioether-substituted diaminocyclopropenium, as an electrolyte additive to limit the cell voltage within the safe value during overcharging. The organic cation demonstrates a record-breaking electrochemical reversibility at ∼4.55 V versus Li+/Li and solubility (0.5 M) in carbonate-based electrolyte. The protection capability of the additive was explored in two cell chemistries: a LiNi0.8Co0.15Al0.05O2/graphite cell and a LiNi0.8Co0.15Al0.05O2/silicon–graphene cell with areal capacities of ∼2.2 mA h cm−2 and ∼3 mA h cm−2, respectively. With 0.2 M addition, the LiNi0.8Co0.15Al0.05O2/graphite cell survived 54 cycles at 0.2C with 100% overcharge. Moreover, the cell can carry an utmost 4.4 mA cm−2 (2C) with 100% overcharge and a maximum capacity of 7540% SOC at 0.2C. [ABSTRACT FROM AUTHOR]

A thin hollow C (HC) was synthesized to host a high phosphorus (P) loading of 75 wt%, forming a P@HC yolk/shell structure, which delivered a reversible capacity of 841 mA h g−1, with excellent rate capability and stable cycling performance. P vapor concentration was found to be critical to the formation of P@HC or the P nanorod (PNR)/C composite. At a very high concentration of P vapor, well-crystallized PNRs were formed, which, however helped to identify the potassiation mechanism. [ABSTRACT FROM AUTHOR]

Metal sulfides are considered as promising anode materials for sodium ion batteries owing to their good redox reversibility and relatively high theoretical capacity. However, their cycle life and rate capability are still unsatisfactory because of poor conductivity and a large volume change during the discharge/charge processes. A facile method for preparing dual carbon-protected metal sulfides is reported. Metal diethyldithiocarbamate complexes are used as precursors. The synthesis only involves a co-precipitation of metal diethyldithiocarbamate complexes with graphene oxide and a subsequent thermal pyrolysis. As an example, N-doped carbon-coated iron sulfides wrapped in the graphene sheets (Fe1−xS@NC@G) are prepared and used as the anode material for a sodium ion battery. The as-synthesized Fe1−xS@NC@G electrode exhibits a high reversible capacity (440 mA h g−1 at 0.05 A g−1), outstanding cycling stability (95.8% capacity retention after 500 cycles at 0.2 A g−1), and good rate capability (243 mA h g−1 at 10 A g−1). Coupled with a Na3V2(PO4)2@C cathode, the full battery exhibits a high capacity retention ratio of 96.5% after 100 cycles and an average output voltage of ca. 2.2 V. More importantly, the proposed synthesis route is universal and can be extended to fabricate diverse transition metal sulfide-based composites with a dual carbon-protected nanostructure for advanced alkali ion batteries. [ABSTRACT FROM AUTHOR]

Nonaqueous redox flow batteries (RFB) can potentially achieve high energy density due to the extended operating voltage windows and redox-active material candidates. However, the development of reversible anode materials with a low redox potential and high solubility is still one of the main challenges. Here, we systematically explore polycyclic aromatic hydrocarbons (PAHs) and their corresponding radical anions (PAHṖn−) as anode redox-active couples with a combination of experimental and computational methods. The results reveal that naphthalene and its radical anion (Nap/NapṖ−) are a promising anode redox-active couple. Paired with catholytes separately containing ferrocenium hexafluorophosphate (FcPF6) and TEMPO, the resulting RFBs can provide theoretical maximum energy densities of 39 W h L−1 and 208 W h L−1, respectively, which are much higher than that of a traditional all-vanadium flow battery (25 W h L−1). As proofs of concept, both static-mode and flow-mode of the as-proposed RFBs are assembled and can deliver dozens of consecutive charge–discharge cycles. [ABSTRACT FROM AUTHOR]

A high capacity alkaline redox storage chemistry is explored based on a novel, environmentally benign zirconia stabilized Fe(6+)/B(2-) chemistry, which sustains an electrochemical potential matched to the pervasive, conventional MnO(2)-Zn battery chemistry, however with a much higher electrochemical capacity.