Current power systems are still highly reliant on dispatchable fossil fuels to meet variable electrical demand. As fossil fuel generation is progressively replaced with intermittent and less predictable renewable energy generation to decarbonize the power system, Electrical energy storage (EES) technologies are increasingly required to address the supply-demand balance challenge over a wide range of timescales. However, the current use of EES technolo. Current power systems are still highly reliant on dispatchable fossil fuels to meet variable electrical demand. As fossil fuel generation is progressively replaced with intermittent and less predictable renewable energy generation to decarbonize the power system, Electrical energy storage (EES) technologies are increasingly required to address the supply-demand balance challenge over a wide range of timescales. However, the current use of EES technologies in power systems is significantly below the estimated capacity required for power decarbonization. This paper presents a comprehensive review of EES technologies and investigates how to accelerate the uptake of EES in power systems by reviewing and discussing techno-economic requirements for EES. Individual EES technologies and power system applications are described, which provides guidance for the appraisal of specific EES technologies for specific power system services. Plausibly required scales and technology types of EES over different regions are then reviewed, followed by discussions on storage cost modelling and predictions for different EES technologies. Opportunities and challenges in developing scalable, economically viable and socio-environmental EES technologies are discussed. The paper explores EES's evolving roles and challenges in power system decarbonization and provides useful information and guidance on EES for further R&D, storage market building and policy making in the transition to zero-carbon power syste. Electrical energy storagePower systemDecarbonizationCost modelling and predictionAFC alkaline fuel cellARES advanced rail energy storageCAES compressed air energy storageCSP concentrated solar powerEES electrical energy storageEDLC Anthropogenic greenhouse gas emissions are a primary driver of climate change and present one of the world's most pressing challenges. To meet the challenge, limiting warming below or close to 1.5 °C recommended by the intergovernmental panel on climate change (IPCC), requires decreasing net emissions by around 45% from 2010 by 2030 and reaching zero net-carbon emissions around 2050. United Nation Environment Programme estimated an yearly 7.6% reduction of greenhouse gas emissions that is required between 2020 and 2030 for the world to get on track towards the 1.5 °C temperature increase limit goal of the Paris Agreement. To highlight the challenge, as a reference, the disruptive Covid-19 pandemic has led to the largest decline of carbon emissions, with its decrease rate the highest ever seen on record. With severe economic and social disruptions, global carbon dioxide emissions are estimated to fall by 6.4%, or a reduction of 2.3 billion tones in 2020 compared to 2019 [,, ], lower than the required average emission target for meeting the IPCC's 1.5 °C temperature increase goal.Energy production of all types accounts for 72% of all emissions. Therefore, rapid and deep decarbonization of energy is critical to ensure a low-carbon system transition consistent with 1.5° C global warming above the pre-industrial level. To meet the climate change target, increasing the use of renewable ene. This section presents an introductive review of various important EES technologies, describes their current state, and compares their key performance metrics. A number of papers focused on detailed comparisons and development of varied EES technologies can be found in the literature [8,12,,, ], as well as technology-specific reviews on.