possesses ultrahigh theoretical capacity (3860 mAh g −1 ), low bulk density (0.53 g cm −3 ), and the lowest negative potential (−3.04 V vs the standard hydrogen electrode). [3] These intriguing advantages make Li metal a promising candidate to be paired with various high-capacity cathodes to generate greater energy than LIBs. [4][5][6] Unfortunately, unveiling the Li anode technology, in reality, is faced with several persistent challenges. The most significant hurdles are the prevalent safety concern and short lifespan caused by the electro-chemo-mechanical instability of Li metal that drives the uncontrollable growth of Li dendrites in repeated cyclic processes. [7] The self-amplified Li dendrites may pierce the separator and cause thermal runaway, short-circuiting, or even explosion. [8,9] Meanwhile, the solid electrolyte interphase (SEI) layer can be broken by Li dendrites, causing continuous consumption of electrolytes/Li sources and eventually, inferior cycle performance. [10] Suppressing dendrite growth is a critical step before making the Li anode viable in the energy storage market. Extensive efforts have been made toward nanostructure design of Li anodes/current collectors, [11][12][13] or applying artificial SEI layers, [14,15] separator coatings, [16][17][18] solid/gel electrolytes, [19][20][21] electrolyte additives, [22,23] and so on. Among these modifications, solid electrolyte-enabled Li metal batteries (LMBs) are recognized as the ultimate choice because they eliminate the safety hazards resulting from leakage or explosion of organic liquid electrolytes; [24] the high mechanical modulus of solid electrolytes is also expected to alleviate the dendrite proliferation. [25] However, solid electrolytes are plagued by lower ionic conductivity and significantly greater interfacial resistance than liquid electrolytes. [26] Gel electrolytes (GEs) integrating the merits of relatively high ionic conductivity and good interfacial properties are regarded as a competent alternative to conquer the obstacles, and it is anticipated to soon broaden their applications practically. [27,28] For decades, a wide variety of GEs based on poly(vinylidene fluoride-co-hexafluoropropylene), [29,30] polyurethane, [31,32] polyacrylonitrile, [33,34] poly(ethylene oxide), [35,36] and more have been investigated to impart improved ionic conductivity at the order of magnitude close to liquid electrolytes (10 -3 S cm −1 ). However, GEs are less effective to suppress Li dendrites because of their insufficient modulus at the mega-Pascal High-voltage lithium metal batteries (LMBs) are a promising high-energydensity energy storage system. However, their practical implementations are impeded by short lifespan due to uncontrolled lithium dendrite growth, narrow electrochemical stability window, and safety concerns of liquid electrolytes. Here, a porous composite aerogel is reported as the gel electrolyte (GE) matrix, made of metal-organic framework (MOF)@bacterial cellulose (BC), to enable long-life LMBs under high voltage. The effective...