For the enhanced electrochemical stability window of LHTO compared to LHTO-pre, the stronger covalent bonds in nano-confined pseudo-water could explain the enhanced electrochemical stability. Water is considered adverse to electrochemical applications due to its narrow electrochemical stability window (1.23 V) and its incompatibility with aprotic electrolytes and metal anodes (e.g., Li metal) . Whereas this traditional cognitive is challenged when water is well-confined 1) in liquid electrolytes (well-known as "water-in-salts" electrolyte or molecular crowding electrolyte ) or 2) in electrodes. For 1), when a water molecule is confined by high-concentrated global/local salts, the electrochemical stability window can be expanded from 1.23 V (H2O) or 2.0 V (traditional aqueous electrolyte), to 2.8 V (21 M LiTFSI), 3.0 V (19.4 M LiTFSI-8.3 M LiBETI) and 3.2 V (2 M LiTFSI-94%PEG-6%H2O) (Table , Supporting Information). For 2), when a water molecule is confined in the crystal structure of Ti-based, V-based, Mn-based electrodes, it can demonstrate 10 4 ~10 5 ultra-stable cycling in aprotic electrolytes beyond the stable window of H2O (Table , Supporting Information), such as 10000 stable cycles for Li1.39H1.18Ti2O5.29-σ (1.0~2.5 V in LIB) , 8000 stable cycles for Mn0.15V2O5•nH2O (0.2~1.7 V in zinc ion battery) , and 1000 stable cycles for NaMnO2-y-δ(OH)2y (2.0~4.0 V in sodium-ion battery) . Therefore, we know that for three different types of water in water-containing oxides, the rank of them by activation energy under heat treatment is adsorbed water < nano-confined water < nano-confined pseudo-water. The sort orders of electrochemical treatment (electrochemical stability) are the same as that of heat treatment (thermal stability). The rank of Li-ion activation energy in an oxide framework is nano-confined pseudo-water < nano-confined water < one without water.