This review summarizes and discusses the state-of-the-art research activities in the area of positive electrode materials for post-lithium ion batteries.

The shortage of lithium resources is promoting the development of cost-efficient battery candidates, especially aqueous rechargeable batteries (ARBs) with high safety and power density. Copper hexacyanoferrate (CuHCF) nanoparticles with high redox potential and rate capability is employed as the battery cathode for hosting ammonium-ion coupling with low-cost zinc anode. Benefiting from the selective ammonium-ion channel in CuHCF, an aqueous rechargeable zinc ammonium hybrid battery is successfully engineered. It presents high cell voltage (1.8 V), outstanding rate performance, low self-discharge, and satisfactory energy density of 114 Wh kg–1 in consideration of total electrodes’ active mass.

Our synthesized ball-cutting Na-FeHCF nanocubes by controlling the stirring speed as a cathode material for ammonium ion storage exhibit high capacity, excellent rate capability, and unparalleled cycling stability.

Aqueous symmetric carbon‐based supercapacitors (CSCs) are always the research focus for energy storage devices because of the virtue of low cost, inherent safety, and encouraging electrochemical stability. As is well‐known, so far most aqueous symmetric CSCs are subjected to low energy densities. Here, a symmetric supercapacitor comprising electrodes from biomass‐derived activated carbon and alkaline–acidic electrolyte is reported. This aqueous symmetric CSC demonstrates exceptional electrochemical performance with high stable working voltage of 2 V and attractive cycling stability of no capacitance loss over 10 000 cycles. Impressively, it shows a remarkable energy density of 36.9 W h kg−1 at 248 W kg−1 based on the total mass of the active materials, which is much higher than traditional aqueous symmetric CSCs, and a power density of 4083 W kg−1 with an energy density of 8.8 W h kg−1. The use of stable alkaline–acidic electrolyte provides an innovative technique to enhance the energy density of aqueous supercapacitors.

Unlike traditional metal-ion insertion, the emerging aqueous rechargeable ammonium-ion batteries (ARABs)b rings new battery chemistries for future stationary energy storage. However, low energy density and low durability hindert he further development of ARABs because of the lack of suitable and cost-efficient anodes. In this study,a na queous rechargeable ammonium zinc hybrid battery is fabricated from durable corner-truncated sodium iron hexacyanoferraten anocubes as the cathode and low-cost zinc as the anode. This novel hybridb attery demonstrates an average workingv oltage of 1.3 V, excellent rate capability,a nd ah igh energy density of 81.7 Wh kg À1 at 286 Wkg À1 (based on two electrodes' active mass), as well as a long lifespan with 92.

A proof-of-concept lithium ion capacitor comprising LiMn2O4 nanorods as the cathode, a nitrogen-rich biomass carbon anode and a stable alkaline–neutral electrolyte was designed and fabricated.

Energy and environmental pollution have become the two major problems in today’s society. The development of green energy storage devices with good safety, high reliability, high energy density and low cost are urgently demanded. Here we report on a lithium ion battery using an aqueous electrolyte solution. It is built up by using graphite coated with gel polymer membrane and LISICON as the negative electrode, and LiFePO4 in aqueous solution as the positive electrode. Its average discharge voltage is up to 3.1 V and energy density based on the two electrode materials is 258 Wh kg−1. It will be a promising energy storage system with good safety and efficient cooling effects.

No abstract