Two exemplary common classes of known electroactive materials that can be used to form the positive electrode 24 are lithium transition metal oxides with layered structures and lithium transition metal oxides with spinel phase. For example, in certain instances, the positive electrode 24 may include a spinel-type transition metal oxide, like lithium manganese oxide (Li_(1+x)Mn_(2?x)O₄), where x is typically <0.15, including LiMn₂O₄ (“LMO”) and lithium manganese nickel oxide LiMn_1.5Ni_0.5O₄ (“ ”). In other instances, the positive electrode 24 may include layered materials like lithium cobalt oxide (LiCoO₂), lithium nickel oxide (LiNiO₂), a lithium nickel manganese cobalt oxide (Li(Ni_xMn_yCo_z)O₂), where 0≤x≤1, 0≤y≤1, 0≤z≤1, and x+y+z=1 (e.g., LiNi_0.6Mn_0.2Co_0.2O₂, LiNi_0.7Mn_0.2Co_0.1O₂, LiNi_0.8Mn_0.1Co_0.1O₂, and/or LiMn_0.33Ni_0.33Co_0.33O₂), a lithium nickel cobalt metal oxide (LiNi_(1?x?y)Co_xM_yO₂), where 0<x<1, 0<y<1 and M may be Al, Mg, Mn, or the like. Other known lithium-transition metal compounds such as lithium iron phosphate (LiFePO₄), lithium iron fluorophosphate (Li₂FePO₄F), or lithium Manganese iron phosphate (LiMnFePO₄) can also be used. In certain aspects, the positive electrode 24 may include an electroactive material that includes manganese, such as lithium manganese oxide (Li_(1+x)Mn_(2?x)O₄), and/or a mixed lithium manganese nickel oxide (LiMn_(2?x)Ni_xO₄), where 0≤x≤1. In a lithium-sulfur battery, positive electrodes may have elemental sulfur as the active material or a sulfur-containing active material.