Heterogeneous Engineering Strategy Derived In Situ Carbon-Encased Nickel Selenides Enabling Superior LIBs/SIBs with High Thermal Safety

Nowadays, the extended usage of lithium/sodium ion batteries (LIBs/SIBs) encounters nerve-wracking issues, including a lack of suitable reservoirs and high thermal runaway hazards. Although using TiO₂ and Li₄Ti₅O₁₂ has been confirmed to be effective in improving battery safety, their low theoretical capacities inevitably cause damage to the electrochemical performance of the battery. Achieving win-win results has become an urgent necessity. This study designed a metal–organic framework (MOF)-derived in situ carbon-coated metal selenide (Ni–Se@G@C) as the anode. When the current density is 0.1–0.3 A g^–1, the initial capacity of LIBs reaches 993.2 mAh g^–1, which increases to 1478.9 mAh g^–1 after running 800 cycles. When running at 2 A g^–1, the cell also offers a relatively high capacity of 458.3 mAh g^–1 after 1500 cycles. After the replacement of graphite with Ni–Se@G@C, the self-heating temperature (T₀) and thermal runaway triggering temperature (T₁) of half and full cells are significantly increased. Meanwhile, the maximum thermal runaway temperature (T₂) and maximal heating release rate (HRR_max) are significantly reduced. Of note, the usage of Ni–Se@G@C enables the battery with superior cycling and rate performance. When used in SIBs, the cell gives an initial discharge capacity of 624.9 mAh g^–1, which still remains at 269.4 mAh g^–1 after running 200 cycles at 1 A g^–1. Notably, E_a of the Ni–Se@G@C cell is 5.6 times higher than that of the graphite cell, corroborating the promoted safety performance. This work provides a new paradigm for MOF-derived micro/nanostructures, enabling the battery with an excellent electrochemical and safety performance portfolio.