Al and Cu foils are the irreplaceable current collectors for Li‐ion batteries (LIBs), and have a great impact on the performance. The sustainability and cost of the current collectors are important factors to improve the circular economy of the battery technologies, and it can be achieved by the effective recycling of spent LIBs. Spent LIBs are a valuable resource with potential environmental hazards owing to the presence of a lot of metals and materials, urging the researchers to recycle/reuse via effective technologies. Of critical importance in this field, is current industry/research efforts toward improving cathode materials; however, the crucial problem is the efficient separation of current collectors from the electrode materials. In this line, this perspective offers the different strategies involved in the separation of current collectors from the electrode materials of spent LIBs and suggests future directions for researchers to develop efficient recycling methodologies.

Spent lithium‐ion batteries (LIBs) offer immense potential in the form of resources such as Li, transition metals (Co, Ni, and Mn), graphite, and Cu, which can be recovered through suitable recycling procedures. The Cu‐current collector is recovered from spent LIBs and converted as a copper oxide (CuO) anode for Na‐ion batteries. The performance of CuO is evaluated with carboxymethyl cellulose (CMC) (CuO–C), and polyvinylidene fluoride (PVdF) (CuO–P) binders in CuO half‐cell and CuO/carbon‐coated Na3V2(PO4)2O2F (CuO/NVPOF) full–cell assemblies. The CuO–C half‐cell displays superior electrochemical performance than CuO–P in terms of cycling and rate performance showing 88% more capacity. To study the stabilization and solid electrolyte interphase growth in CuO–C, an in situ impedance study is conducted. However, the full‐cell, CuO–P/NVPOF displays better capacity retention during cycling with Coulombic efficiency >95% from the second cycle, whereas CuO‐C/NVPOF could hardly maintain only >90%. For conversion type CuO, it is apparent that, though the CMC binder supports half‐cell performance, the PVdF binder is suitable for the practical cell/full‐cell configuration.

Spent Li‐ion batteries are efficiently recycled by extracting and reusing the anode active material, graphite, through a simple yet effective and scalable technique as anode for the sodium‐ion battery (SIB). The recovered graphite (RG) half‐cell rendered a capacity of >120 mAh g−1 via the solvent‐co‐intercalation process. An in situ impedance is performed to assess the robustness of the electrolyte for the extended cycling. The performance of RG is evaluated in a full‐cell with carbon‐coated Na3V2(PO4)3 cathode, which exhibits capacity retention of 78% after 100 cycles. In addition, a temperature dependence performance of the full‐cell is studied from −10 to 40 °C, where it exhibits outstanding low‐temperature performance. The full‐cell provides an energy density of 78 Wh kg−1 at ambient temperature conditions. Recovery of active materials for SIB will drive down the cost/kWh and act as a green technology to dispose of spent Li‐ion batteries.

The advantage of hybridizing battery and supercapacitor electrodes has succeeded recently in designing hybrid charge storage systems such as lithium‐ion capacitors (LICs) with the benefits of higher energy than supercapacitors and more power density than batteries. However, sluggish Li‐ion diffusion of battery anode is one of the main barriers and hampers the development of high‐performance LICs. Herein, is introduced a new conversion/displacement type anode, MnCO3, via effectively recycling spent Li‐ion batteries cathodes for LICs applications. The MnCO3 cuboids are regenerated from the spent LiMn2O4 cathodes by organic acid lixiviation process, and hydrothermal treatment displays excellent reversibility of 535  mAh g−1 after 50  cycles with a Coulombic efficiency of >99%. Later, LIC is assembled with the regenerated MnCO3 cubes in pre‐lithiated form (Mn0 + Li2CO3) as anode and commercial activated carbon (AC) as the cathode, delivering a maximum energy density of 169.4 Wh kg−1 at 25 °C with ultra‐long durability of 15,000 cycles. Even at various atmospheres like −5 and 50 °C, this LIC can offer a energy densities of 53.8 and 119.5 Wh kg−1, respectively. Remarkably, the constructed AC/Mn0 + Li2CO3‐based LIC exhibits a good cycling performance for a continuous 1000 cycles with >91% retention invariably for all temperature conditions.

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