Alkali metal ion source with moderate rate of ion release and methods of forming

An alkali metal ion source with a moderate rate of ion release, formed by a method comprising the steps of:

• a) combining a first component particulate alkali metal ion-bearing framework silicate with a second component that includes at least one of an oxide and a hydroxide of at least one of an alkaline earth metal and an alkali metal to form a solid mixture, wherein the molar ratio of the silicon to the at least one of the alkaline earth metal and alkali metal of the second component is in a range of between about 1.0:0.1 and about 1.0:0.3;
• and
• b) exposing the solid mixture to a hydrothermal treatment to form a gel that includes the silica and the alkali metal of the first component, thereby forming the alkali metal ion source, comprised of the alkali metal ion bearing silicate gel in amount of not less than 10 wt. %, wherein the alkali metal ion source has a specific surface area (BET) between about 8 m2/g and about 50 m2/g, wherein the alkali metal ion source releases not less than 1 g of potassium per 1 kg of the alkali metal ion source and not less than 1 wt. % of silica acid within 24 hours upon exposure to aqueous solution that is undersaturated with respect to potassium and silica.