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Lithium (Li) metal anode holds great promise for high-energy-density rechargeable batteries. However, it suffers from the Li dendrites growth and uncontrollable side reactions with electrolyte due to the unstable solid electrolyte interphase (SEI) layer. Herein, we propose a facile strategy for the in-situ fabricate of organic-inorganic composite artificial SEI layers on Li surfaces, which consist of organic fluorinated siloxane and inorganic LiF-rich phases. The hybrid artificial SEI endows high mechanical strength (13.1 GPa) and Li+ transfer number (0.62). Such robust SEI protective layers can not only guide uniform nucleation and deposition of Li metal by facilitating uniform Li-ion distribution, but also prevent unfavourable side reactions. Accordingly, the protected metallic lithium anode (PMTFPS-Li) anode enables stable Li plating/stripping performance in symmetric cells for more than 300 h at 4 mA ·h/cm2 under a high areal capacity of 4 mA/cm2. Moreover, the PMTFPS-Li/S cells could maintain more than 300 stable cycles at 0.5C and the PMTFPS-Li/LFP cells present excellent cycling performance (400 cycles at 1C) and enhanced rate capability (110.4 mA·h/g at 3 C). This work will inspire the design of artificial SEI on Li anodes for advanced Li metal batteries.

With the frequent occurrence of private data breaches, it is now more necessary than ever to address how to protect private data. The combination of Ciphertext-Policy Attribute-Based Encryption (CP-ABE) and blockchain typically enables secure storage and sharing of data. However, in high-dimensional attribute domains, that is, the number of attributes is large, these schemes have issues such as low security of data protection, high computational overhead, and high cost of attribute revocation. This paper proposes a personal privacy data protection scheme for encryption and revocation of high-dimensional attribute domains to address these issues. The proposed scheme is made up of three components. Firstly, Fast High-dimensional Attribute Domain-based Message Encryption (HAD-FME) is proposed to improve data security and reduce computational cost. Secondly, an Attribute Revocation Mechanism Based on Sentry Mode (SM-ARM) is designed in combination with smart contracts. Lastly, a Blockchain-based Model for Personal Privacy Data Protection (BC-PPDP) is proposed by integrating HAD-FME with SM-ARM. The security analysis results show that HAD-FME proposed in this paper is secure under the DLIN assumption, and the attribute revocation satisfies both forward and backward security. Experiments show that HAD-FME has higher computational efficiency than existing schemes in the high-dimensional attribute domains, SM-ARM has lower revocation cost than existing attribute revocation mechanisms, and smart contracts and blockchain work well.

The data hierarchical Ciphertext-Policy Attribute-Based Encryption (CP-ABE) scheme implements multiple hierarchical data encryption of a single access policy, which reduces the computation and storage overhead. However, existing data hierarchical CP-ABE schemes have some problems, such as the leakage of personal privacy information through access policies or user attributes in plaintext form, and these schemes grant enough privileges to a single authorization center. If the authorization center is untrusted or attacked, keys can be used to illegally access data, which is the key escrow problem. To solve these problems, we propose an Attribute Hiding and Multiple Authorization Centers-based Data Hierarchical Encryption Scheme (AH-MAC-DHE). Firstly, we propose an Attribute Convergence Hiding Mechanism (ACHM). This mechanism solves the problem of personal privacy information leakage by hiding access policies and user attributes. Secondly, we design Privilege-Dispersed Multiple Authorization Centers (PD-MAC). PD-MAC solves the problem of key escrow by dispersing the privileges of the single authorization center to the user authorization center and attribute authorization center. Finally, we prove that AH-MAC-DHE is secure under the decisional q-parallel Bilinear Diffie-Hellman Exponent (BDHE) assumption, which also satisfies anti-collusion and privacy security. The experimental results indicate that compared with existing schemes, AH-MAC-DHE performs well. [ABSTRACT FROM AUTHOR]

The sluggish kinetics of complicated multiphase conversions and the severe shuttling effect of lithium polysulfides (LiPSs) significantly hinder the applications of Li‐S battery, which is one of the most promising candidates for the next‐generation energy storage system. Herein, a bifunctional electrocatalyst, indium phthalocyanine self‐assembled with carbon nanotubes (InPc@CNT) composite material, is proposed to promote the conversion kinetics of both reduction and oxidation processes, demonstrating a bidirectional catalytic effect on both nucleation and dissolution of Li2S species. The theoretical calculation shows that the unique electronic configuration of InPc@CNT is conducive to trapping soluble polysulfides in the reduction process, as well as the modulation of electron transfer dynamics also endows the dissolution of Li2S in the oxidation reaction, which will accelerate the effectiveness of catalytic conversion and facilitate sulfur utilization. Moreover, the InPc@CNT modified separator displays lower overpotential for polysulfide transformation, alleviating polarization of electrode during cycling. The integrated spectroscopy analysis, HRTEM, and electrochemical study reveal that the InPc@CNT acts as an efficient multifunctional catalytic center to satisfy the requirements of accelerating charging and discharging processes. Therefore, the Li–S battery with InPc@CNT‐modified separator obtains a discharge‐specific capacity of 1415 mAh g−1 at a high rate of 0.5 C. Additionally, the 2 Ah Li–S pouch cells deliver 315 Wh kg−1 and achieved 80% capacity retention after 50 cycles at 0.1 C with a high sulfur loading of 10 mg cm−2. Our study provides a practical method to introduce bifunctional electrocatalysts for boosting the electrochemical properties of Li–S batteries. [ABSTRACT FROM AUTHOR]

Promoting the reversible structural transformation and carrier migration dynamics simultaneously in a multiple ion-involved process is vital for sulfide electrode materials. Herein, TiS2 with a sulfide cluster vacancy (CV–TiS2−x) has been calculated and prepared to explore a novel strategy to improve the electrochemistry reversibility of sulfide electrodes. It is found that the cluster vacancy can serve as an effective control factor for the improvement of the Fermi level, and enhances the electrochemical stability of CV–TiS2−x in the liquid organic electrolyte system. Moreover, owing to the plentiful positively charged S-vacancies, the CV–TiS2−x samples exhibit an extended interplanar spacing and retain their structural integrity during the lithium ion insertion process. The integrated HRTEM, in situ XRD, XPS analysis and electrochemical study reveal that the cluster vacancy is not only responsible for an increase in reversible performance, but also boosting the anionic redox reaction of (S2)2− species. Therefore, the CV–TiS2−x electrode delivers a reversible capacity of 650 mA h g−1 for 300 cycles at a current density of 1C (220 mA g−1). Our study provides a novel strategy of introducing sulfur cluster vacancies to improve the electrochemical activity of TiS2, which can be applied to other sulfide electrodes. [ABSTRACT FROM AUTHOR]

Volume changes, polysulfide shuttle effects, and low Li-ion/electronic conductivity of sulfide electrodes limit their application in Li-ion batteries with high-energy density. Here, micron FeS2 particles with bifunctional carbon nanotubes (FeS2@B–CNTs) including CNT internal conductive networks and external protective cages were prepared by a one-step solvothermal method. The internal CNTs anchor FeS2via chemical binding, which much more effectively inhibited the shuttle effect than physical confinement alone. Meanwhile, reticular CNT cages were generated on the surface of the composite FeS2 micron particles, buffering volumetric changes during cycling and further restraining the shuttle of polysulfides. Additionally, a three-dimensional CNT framework offered a primarily continuous charge transfer pathway. The FeS2@B–CNTs electrode had a high initial coulombic efficiency of 91.3% and delivered a capacity of 698 mA h g−1 over 500 cycles at 1000 mA g−1. The Li-ion diffusion coefficient is two orders of magnitude higher than those of previous reports, which improved the rate performance of the FeS2@B–CNTs electrode. These studies on micron FeS2 spheres shed light on the design strategies for the application of sulfide electrodes. [ABSTRACT FROM AUTHOR]

To mitigate the gradual phase transition and improve the structural stability of Li-rich layered cathode materials, an antisite defect nanolayer (transition-metal ions replacing Li+ in a Li slab) with a thickness of approximately 2 nm was induced on the surface of Li1.16(Ni0.25Mn0.75)0.84O2 by doping with boracic polyanions. It is found that the 2 and 3 mol % BO33−-doped samples show excellent cycling stability with capacity retentions of 91.2 and 93.7 %, respectively, after 300 cycles at 0.5 C. More importantly, the BO33− doping restrains the decay of discharge voltage upon cycling and has the prospect to overcome the fatal drawback of Li-rich layered oxides. The results demonstrate that the BO33− doping contributes to the generation of an antisite defect nanolayer on the surface, which hinders the formation of Li-ion vacancies and the continued migration of more transition-metal ions to the Li slab in a deep charging state. The antisite defect nanolayer clearly improves surface structural stability and inhibits the appearance of the amorphous domain in the bulk, which are favorable to maintain the facile lithium-diffusion pathways during cycling and improve the capacity retention and rate capability. [ABSTRACT FROM AUTHOR]