Murdochite-type Ni₆MnO₈ three-dimensional mesoporous nanosheet arrays grown on carbon cloth (NMO-SA/CC) are synthesized using an in-situ growth strategy. As self-supported binder-free anodes for LIBs, the NMO-SA/CC hierarchical nanostructures exhibit ultrahigh capacity, excellent cycling stability, and good rate capability. The excellent lithium storage performance can be ascribed to the perfect electrical contact between NMO-SA and CC. The mesopores in the thin nanosheet can maximize the electrode contact with the electrolyte by decreasing the Li⁺ diffusion path. Moreover, these effects relieve the pulverization and agglomeration that originate from the large volume variations during the Li⁺ intercalation/deintercalation cycles. The in-situ X-ray absorption fine structure (XAFS) spectrum recorded during the initial lithiation/delithiation processes reveals the conversion reaction process.