The huge consumption of fossil fuels leads to excessive CO 2 emissions, and its reduction has become an urgent worldwide concern. The combination of renewable energies with battery energy storage, and carbon capture, utilization, and storage are well acknowledged as two major paths in achieving carbon neutrality. However, the former route faces the discard problem of a large amount of lithium-ion batteries (LIBs) due to their limited lifespan, while it is costly to obtain effective CO 2capturing materials to put the latter into implementation. Herein, for the first time, we propose a route to synthesize low-cost Li 4 SiO 4 as CO 2 sorbents from spent LIBs, verify the technical feasibility, and evaluate the CO 2 adsorption/desorption performance. The results show that Li 4 SiO 4 synthesized from the cathode with self-reduction by the anode graphite of LIBs has a superior CO 2 capacity and cyclic stability, which is constant at around 0.19 g/g under 15 vol % CO 2 after 80 cycles. Moreover, the cost of fabricating sorbents from LIBs is only 1/20−1/3 of the conventional methods. We think this work can not only promote the recycling of spent LIBs but also greatly reduce the cost of preparing Li 4 SiO 4 sorbents, and thus could be of great significance for the development of CO 2 adsorption. KEYWORDS: recycling of spent lithium-ion batteries, Li 4 SiO 4 sorbent, high-temperature CO 2 adsorption, adsorption and desorption

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Renewable energy and electric vehicles are well-acknowledged strategies for reducing CO 2 emissions, and their development relies heavily on the core of energy storage systems using lithium-ion batteries. However, recycling of lithium-ion batteries is far from mature, and massive abandonment of spent batteries would lead to severe environmental pollution. Meanwhile, the shortage of lithium resources brought about by the rapid development of lithium-ion batteries, especially LiFePO 4 , significantly drives up the preparation cost of Li 4 SiO 4 as a promise sorbent and greatly limits its application as a CO 2 capture scheme. Hence, a strategy is urgently needed to alleviate the lithium resource contradiction between energy storage and CO 2 mitigation. Herein, we report a novel concept in recycling spent LiFePO 4 battery to prepare high-efficiency and low-cost Li 4 SiO 4 sorbents for CO 2 capture. The obtained Li 4 SiO 4 sorbents demonstrate very stable CO 2 capacities of 0.27− 0.28 g/g in a typical test up to 80 cycles, a leading level in CO 2 capture, while the cost is only 1/6 of the conventional preparation process. It suggests that the concept of recycling spent LiFePO 4 for CO 2 capture has broad implications on resource utilization of energy waste and the mitigation of CO 2 emissions. KEYWORDS: CO 2 adsorption, spent lithium-ion battery, Li 4 SiO 4 , high-temperature CO 2 sorbent