This paper reviews recent advances in grid-connected battery energy storage and sets them against the challenges that continue to limit their translation into inclusive outcomes. Adopting a socio-technical perspective, it treats technical progress and social adaptation as interdependent rather than separable, and it argues that capability has in many respects outpaced the institutional, governance, and equity frameworks needed to realize it in the field. The review pays particular attention to the inequity embedded in warranty terms and the scarcity of replacement capital where degradation is fastest, which it frames as a binding consideration that technical advance alone cannot resolve. The contribution is conceptual rather than empirical: this paper synthesizes the direction of recent progress, characterizes the persistent technical and social challenges that remain open, and proposes a conceptual agenda by which advances in grid-connected battery energy storage might be aligned with the goal of energy systems that are efficient, accessible, responsive, and adaptable for resource-dependent regions.