Heterogeneous\nEngineering Strategy Derived In Situ\nCarbon-Encased Nickel Selenides Enabling Superior LIBs/SIBs with High\nThermal Safety

Nowadays,\nthe extended usage of lithium/sodium ion batteries (LIBs/SIBs)\nencounters nerve-wracking issues, including a lack of suitable reservoirs\nand high thermal runaway hazards. Although using TiO<sub>2</sub> and\nLi<sub>4</sub>Ti<sub>5</sub>O<sub>12</sub> has been confirmed to be\neffective in improving battery safety, their low theoretical capacities\ninevitably cause damage to the electrochemical performance of the\nbattery. Achieving win-win results has become an urgent necessity.\nThis study designed a metal–organic framework (MOF)-derived\nin situ carbon-coated metal selenide (Ni–Se@G@C) as the anode.\nWhen the current density is 0.1–0.3 A g<sup>–1</sup>, the initial capacity of LIBs reaches 993.2 mAh g<sup>–1</sup>, which increases to 1478.9 mAh g<sup>–1</sup> after running\n800 cycles. When running at 2 A g<sup>–1</sup>, the cell also\noffers a relatively high capacity of 458.3 mAh g<sup>–1</sup> after 1500 cycles. After the replacement of graphite with Ni–Se@G@C,\nthe self-heating temperature (<i>T</i><sub>0</sub>) and\nthermal runaway triggering temperature (<i>T</i><sub>1</sub>) of half and full cells are significantly increased. Meanwhile,\nthe maximum thermal runaway temperature (<i>T</i><sub>2</sub>) and maximal heating release rate (HRR<sub>max</sub>) are significantly\nreduced. Of note, the usage of Ni–Se@G@C enables the battery\nwith superior cycling and rate performance. When used in SIBs, the\ncell gives an initial discharge capacity of 624.9 mAh g<sup>–1</sup>, which still remains at 269.4 mAh g<sup>–1</sup> after running\n200 cycles at 1 A g<sup>–1</sup>. Notably, <i>E</i><sub>a</sub> of the Ni–Se@G@C cell is 5.6 times higher than\nthat of the graphite cell, corroborating the promoted safety performance.\nThis work provides a new paradigm for MOF-derived micro/nanostructures,\nenabling the battery with an excellent electrochemical and safety\nperformance portfolio.