A lithium titanate has the following formula: Li4Ti5O12−x wherein x is greater than 0. The lithium titanate is formed by providing a mixture of titanium dioxide and a lithium-based component. The mixture is sintered in a gaseous atmosphere comprising a reducing agent to form the lithium titanate having the above formula. A lithium-based cell includes an electrolyte, an anode, and a cathode, with at least one of the anode and the cathode comprising the lithium titanate having the above formula. The lithium titanate is deficient of oxygen, which increases electronic conductivity of the lithium titanate by at least three orders over electronic conductivity of a stoichiometric lithium titanate, while avoiding loss of reversible electric power-generating capacity that typically occurs when doping is used to replace titanium in the lithium titanate with atoms that provide higher electronic conductivity.