The two major limitations in the application of SnO₂ for lithium-ion battery (LIB) anodes are the large volume variations of SnO₂ during repeated lithiation/delithiation processes and a large irreversible capacity loss during the first cycle, which can lead to a rapid capacity fade and unsatisfactory initial Coulombic efficiency (ICE). To overcome these limitations, we developed composites of ultrafine SnO₂ nanoparticles and in situ formed Co(CoSn) nanocrystals embedded in an N-doped carbon matrix using a Co-based metal–organic framework (ZIF-67). The formed Co additives and structural advantages of the carbon-confined SnO₂/Co nanocomposite effectively inhibited Sn coarsening in the lithiated SnO₂ and mitigated its structural degradation while facilitating fast electronic transport and facile ionic diffusion. As a result, the electrodes demonstrated high ICE (82.2%), outstanding rate capability (~ 800 mAh g⁻¹ at a high current density of 5 A g⁻¹), and long-term cycling stability (~ 760 mAh g⁻¹ after 400 cycles at a current density of 0.5 A g⁻¹). This study will be helpful in developing high-performance Si (Sn)-based oxide, Sn/Sb-based sulfide, or selenide electrodes for LIBs. In addition, some metal organic frameworks similar to ZIF-67 can also be used as composite templates.

The structures and surface adsorption sites of Pd–Ir nanoalloys are crucial to the understanding of their catalytic performance because they can affect the activity and selectivity of nanocatalysts. In this article, density functional theory (DFT) calculations are performed on bare Pd–Ir nanoalloys to systematically explore their stability and chemical ordering properties, before studying the adsorption of CO on the nanoalloys. First, the structural stability of 38-atom and 79-atom truncated octahedral (TO) Pd–Ir nanoalloys are investigated. Then the adsorption properties and preferred adsorption sites of CO on 38-atom Pd–Ir nanoalloys are considered. The Pd_shellIr_core structure, which has the lowest energy of all the considered isomers, exhibits the highest structural stability, while the Pd_coreIr_shell configuration is the least stable. In addition, the adsorption strength of CO on Ir atoms is found to be greater than on Pd for Pd–Ir nanoclusters. The preferred adsorption sites of CO on pure Pd and Ir clusters are in agreement with calculations and experiments on extended Pd and Ir surfaces. In addition, d-band center and charge effects on CO adsorption strength on Pd–Ir nanoalloys are analyzed by comparison with pure clusters. The study provides a valuable theoretical insight into catalytically active Pd–Ir nanoalloys.

Spatial confinement is a desirable successful strategy to trap sulfur within its porous host and has been widely applied in lithium–sulfur (Li–S) batteries. However, physical confinement alone is currently not enough to reduce the lithium polysulfide (Li₂S_n, 4 ≤ n ≤ 8, LIPSs) shuttle effect with sluggish LIPS-dissolving kinetics. In this work, we have integrated spatial confinement with a polar catalyst, and designed a three-dimensional (3D) interconnected, Co decorated and N doped porous carbon nanofiber (Co/N-PCNF) network. This Co/N-PCNF film serves as a freestanding host for sulfur trapping, which could effectively facilitate the infiltration of electrolyte and electron transport. In addition, the polar Co species possess strong chemisorption with LIPSs, catalyzing their reaction kinetics as well. As a result of this rational design and integration, the Co/N-PCNF@S cathode with a sulfur loading of 2 mg cm⁻² exhibits a high initial discharge capacity of 878 mA h g⁻¹ at 1C, and maintains a discharge capacity of 728 mA h g⁻¹ after 200 cycles. Even with high sulfur loading of 9.33 mg cm⁻², the cathode still keeps a stable areal capacity of 7.16 mA h cm⁻² at 0.2C after 100 cycles, which is much higher than the current areal capacity (4 mA h cm⁻²) of commercialized lithium-ion batteries (LIBs). This rational design may provide a new approach for future development of high-density Li–S batteries with high sulfur loading.

Timely and accurate fault diagnosis for a lithium-ion battery pack is critical to ensure its safety. However, the early fault of a battery pack is difficult to detect because of its unobvious fault effect and nonlinear time-varying characteristics. In this paper, a fault diagnosis method based on relative entropy and state of charge (SOC) estimation is proposed to detect fault in lithium-ion batteries. First, the relative entropies of the voltage, temperature and SOC of battery cells are calculated by using a sliding window, and the cumulative sum (CUSUM) test is adopted to achieve fault diagnosis and isolation. Second, the SOC estimation of the short-circuit cell is obtained, and the short-circuit resistance is estimated for a quantitative analysis of the short-circuit fault. Furthermore, the effectiveness of our method is validated by multiple fault tests in a thermally coupled electrochemical battery model. The results show that the proposed method can accurately detect different types of faults and evaluate the short-circuit fault degree by resistance estimation. The voltage/temperature sensor fault is detected at 71 s/58 s after faults have occurred, and a short-circuit fault is diagnosed at 111 s after the fault. In addition, the standard error deviation of short-circuit resistance estimation is less than 0.12 Ω/0.33 Ω for a 5 Ω/10 Ω short-circuit resistor.