Abstract: Methods and systems are provided for manufacturing and implementing solid-state electrolytes (SSEs) for aluminum-based rechargeable batteries and other secondary batteries. In some examples, a SSE composition may include a mixture including urea, sodium chloride, sodium borate, magnesium sulfate, and sodium silicate. In certain examples, the SSE composition may further include carboxymethyl cellulose. In some examples, an aluminum-based secondary battery may be formed by applying a first portion of the SSE composition to an aluminum-based anode via slot-die coating and a second portion of the SSE composition to a cellulose membrane to form a SSE layer, and combining the coated aluminum-based anode, the SSE layer, and a sulfur-based cathode. In certain examples, a current pulse may be applied to the aluminum-based secondary battery to activate in situ solid-electrolyte interphase layers.