Tunnel‐structured polyantimonic acid (PAA) is an intriguing high‐capacity anode candidate for alkali‐metal‐ion storage; however, the awful electroconductivity of PAA (≈10–10 S cm–1) normally requires coupling with large‐surface‐area conductive substrate (e.g., graphene), conversely leading to poor scalability, ultralow density, and execrable volumetric energy. Synergistic structural engineering of PAA via bulk‐phase ion substitution and incorporation with low‐cost flake graphite (FG) is presented here to construct composite electrodes for lithium‐storage. The full‐occupation of Mn2+ into the tunnel‐centers of PAA synchronously improves its bulk conductivity (≈10–5 S cm–1) and true density (4.58 g cm–3), whilst less than 20% volume expansion of PAA is consequently achieved by FG confinement with enhanced multielectron‐reaction kinetics, unveiled by ex/in situ techniques. Besides delivering considerable volumetric capacity (>1200 mAh cm–3 at 0.1 A g–1), thus‐fabricated high‐tap‐density composite favors the construction of conducting additive‐free, high‐loading thick electrodes (>6.0 mg cm–2), exhibiting dual‐boosted areal/volumetric capacities (4.2 mAh cm–2/743 mAh cm–3), and fast‐charging capability (75% capacity charged within ≈13 min). Moreover, 3D‐printed composite electrodes with tunable shape and mass‐loading are also implemented to showcase impressive areal/volumetric Li+‐storage performance. Paring with high‐loading and high‐compact‐density LiCoO2 cathodes (e.g., 18.0 mg cm–2/3.53 g cc–1), full‐cells achieve remarkable electrode‐level areal‐/volumetric‐energy‐densities beyond 7.0 mWh cm–2/850 Wh L–1cathode+anode.

Transition metal oxides with high capacity still confront the challenges of low initial coulombic efficiency (ICE, generally <70%) and inferior cyclic stability for practical lithium-storage. Herein, a hollow slender carambola-like Li 0.43 FeO 1.51 with Fe vacancies is proposed by a facile reaction of Fe 3+ -containing metal-organic frameworks with Li 2 CO 3 . Synthesis experiments combined with synchrotron-radiation X-ray measurements identify that the hollow structure is caused by Li 2 CO 3 erosion, while the formation of Fe vacancies is resulted from insufficient lithiation process with reduced Li 2 CO 3 dosage. The optimized lithium iron oxides exhibit remarkably improved ICE (from 68.24% to 86.78%), high-rate performance (357 mAh g −1 at 5 A g −1 ), and superior cycling stability (884 mAh g −1 after 500 cycles at 0.5 A g −1 ). Paring with LiFePO 4 cathodes, the full-cells achieve extraordinary cyclic stability with 99.3% retention after 100 cycles. The improved electrochemical performances can be attributed to the synergy of structural characteristics and Fe vacancy engineering. The unique hollow structure alleviates the volume expansion of Li 0.43 FeO 1.51 , while the in situ generated Fe vacancies are powerful for modulating electronic structure with boosted Li + transport rate and catalyze more Li 2 O decomposition to react with Fe in the first charge process, hence enhancing the ICE of lithium iron oxide anode materials.

Lithium‐Ion Batteries In article number 2200653, Kaipeng Wu, Hao Wu and co‐workers report the synergistic structural engineering of tunnel‐type polyantimonic acid via bulk‐phase Mn2+ ion substitution and flake graphite incorporation, which endows superior conductive architecture and high tap density, hence simultaneously realizing structural stability, fast charging, and high volumetric/areal energy storage toward high‐mass‐loading, printable lithium‐ion battery anodes.

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