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The dual-site doping method combines three-fold benefits to enhance LiNi 0.9 Co 0.1 O 2 stability. [Display omitted] • A new Mg/Ta dual-site doping strategy was proposed for high-nickel LiNi 0.9 Co 0.1 O 2. • Mg2+ and Ta5+ ions reside in the 3a and 3b crystallographic sites respectively. • Mg2+ ions prevent Li+/Ni2+ anti-site exchange and inhibit detrimental phase transition. • Ta5+ ions expand layer spacing and induce LiTaO 3 surface coating and well-ordered structure. • The dual-site doping method combines three-fold benefits to enhance LiNi 0.9 Co 0.1 O 2 stability. Due to its high specific capacity and low cost, high-nickel layered oxide LiNi 0.9 Co 0.1 O 2 has found promising application as the cathode materials for lithium-ion batteries. However, the crystallographic instability induced by Li+/Ni2+ anti-site exchange, the interfacial parasitic reactions and the microcracking caused by internal stress jointly contribute to the mechano-chemical failure of LiNi 0.9 Co 0.1 O 2 , leading to its fast capacity decay and high thermal stability concern. In this regard, a Mg/Ta dual-site doping strategy was proposed for LiNi 0.9 Co 0.1 O 2 , for which Mg2+ was doped in situ during the synthesis of cathode precursor, while Ta5+ ions were incorporated after the precursor synthesis. This novel synthesis approach leads to unique dual-site occupations of Mg2+ and Ta5+ in the 3a and 3b crystallographic sites respectively. The Mg2+ ions residing in 3a site can function as pillar ions by preventing the Li+/Ni2+ anti-site exchange and inhibiting layered to rock-salt phase transition. The Ta5+ ions occupying 3b site not only leads to the expanded lithium layer spacing but also creates interfacial protection and well-ordered microstructure in LiNi 0.9 Co 0.1 O 2. Consequently, the dual-site-doped LiNi 0.9 Co 0.1 O 2 outperforms the pristine and single-site-doped samples. For instance, its full cell shows a greatly enhanced cycling stability from 57.3 % to 90.5 % after 300 cycles at 1C/1C and well improved thermal stability from 205.2 °C to 225.6 °C, compared to the pristine sample. This Mg/Ta dual-site doping strategy provides a facile and practical way to improve the electrochemical and thermal performances of high-nickel layered cathode material LiNi 0.9 Co 0.1 O 2. [ABSTRACT FROM AUTHOR]

[Display omitted] • PEO-based polymer-in-salt electrolytes are made by a facile coating process. • Rich hydrogen bonds are formed in polymer network for better structural stability. • High content of free Li+ and restricted anion movement obtain a high t Li + of 0.639. • Inhibition of Li dendrites renders Li/Li cells cycling over 3000 h at 0.2 mA cm−2. • The electrolytes boost the performances of LMBs using LFP or NCM88 significantly. Polyethylene oxide (PEO)-based solid polymer electrolyte (SPEs) is full of attraction due to its exceptional lithium ion dissolubility and strong resistance toward lithium metal reduction. Nevertheless, it still suffers from the unfulfilling room temperature ionic conductivity and poor mechanical properties. Herein, a flexible and robust polymer-in-salt electrolyte based on composite of polybenzimidazole (PBI) and PEO via a facile preparation approach has been developed for room-temperature lithium metal batteries (LMBs). The rigid framework structure of PBI and dense hydrogen bonds formed between PBI and PEO jointly reinforce the structural stability of SPEs at high lithium salt concentration, which makes the SPEs possess sufficient mechanical properties to resist the lithium dendrites growth. The thermal stability and fire resistance of SPEs have also been improved relying on the distinctive flame retardancy and incombustibility of PBI. Besides, PBI is prone to forming hydrogen bonds with lithium salt anions to limit their mobility, while the rich N atoms on PBI chains can promote the dissociation of lithium salt through electrostatic attraction interaction. Their synergistic effects make the PEO-based polymer-in-salt electrolytes achieve the high room temperature ionic conductivity of 5.7 × 10−4 S cm−1, wide electrochemical window of 4.45 V, and large lithium transference number of 0.639. When applied to LMBs with LiFePO 4 or LiNi 0.88 Co 0.06 Mn 0.06 O 2 cathode, both coin cells exhibit improved cycling performance and rate capability. Furthermore, the LiNi 0.88 Co 0.06 Mn 0.06 O 2 /SiO x -C pouch cells using the SPEs demonstrate remarkable flexibility and safety, clarifying that the PEO-based polymer-in-salt electrolytes possess a promising application prospect for safe and high-performance LMBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • P-doped NiS 2 hierarchical architectures with sulfur vacancies are synthesized. • The amounts of P dopants and sulfur vacancies could be precisely controlled. • The optimal catalyst manifests excellent catalytic performance with duriability. • The P dopant activates the electrochemical activities of neighboring Ni and S sites. • The association of P doping with S vacancies tunes the d-band center position. The synergistic achievement of heteroatom doping, defect engineering and appropriate structural design is efficient to adjust and boost the catalytic performance of catalysts yet challenging. Herein, phosphorus (P)-doped NiS 2 hierarchical architectures with sulfur vacancies are synthesized via a Prussian-blue-analogue-sacrificed strategy followed by a phosphidation process. By modulation of P doping and sulfur vacancies, the optimal catalyst manifests outstanding electrocatalytic activities, affording low overpotentials of 73 mV at 10 mA cm−2 for hydrogen evolution reaction (HER), and 255 mV at 20 mA cm−2 for oxygen evolution reaction (OER), respectively. Density functional theory calculations certify that the P dopant not only serves as the new active sites, but also activates the electrochemical activity of neighboring Ni and S sites. Moreover, the synergistic effect of P-doping and sulfur vacancies further improve electrochemical activities of HER and OER by optimizing the adsorption free energy of hydrogen (ΔG H*) and oxygen-containing intermediates (OH*, O* and OOH*), respectively. This finding provides a directive strategy to achieve efficient non-noble metal catalysts for energy conversion and storage. [ABSTRACT FROM AUTHOR]