Multivalent Ion Storage Mechanism New Strategy for Storing Enormous Energy at a Fast Rate

Abstract

The use of electricity generated from clean and renewable sources, such as water, wind, or sunlight, requires efficient electrical energy storage by high power and energy secondary batteries using abundant, low cost materials in sustainable processes. It is stated in American Science Policy Reports that the next-generation “beyond-lithium” (or beyond univalent ion) battery chemistry is a feasible solution for such goals [ 1 ,2]. At first, we discover new “multivalent ion” battery chemistries beyond “univalent lithium” battery chemistry. We show from theoretic calculation and experiment confirmation that storage of multivalent ions (Ni2+, Zn2+, Mg2+, Ca2+, Ba2+, or La3+ ions) in alpha type manganese dioxide presents a more stable thermodynamics and faster kinetics than storage of univalent ions. As shown in Figure 1 we further use the intercalation of multivalent ions into alpha manganese dioxide to invent two rechargeable multivalent ion batteries (MIBs), named as zinc ion battery and nickel ion battery and to design a series of asymmetric supercapacitors[3]. Subsequently we discovered a reversible manganese reduction/oxidation process on manganese dioxide/graphene composite for storing enormous energy at a fast rate. Oxygen reduction/evolution reaction (ORR/OER) is a basic process for fuel cells or metal air batteries. However, ORR/OER generally requires noble metal catalysts and suffers from low solubility (10-3 molar per liter) of O2, low kinetics rate (10-6 cm2/s) and low reversibility[4]. Here we report a manganese reduction/oxidation reaction (MRR/MOR) on graphene/MnO2 composites, delivering a high capacity (4200 mAh/g), fast kinetics (2.4×10-3 cm2/s, three orders higher than ORR/OER), high solubility (three orders than O2), and high reversibility (100%).We further use MRR/MOR to invent a multivalent manganese ion battery (MIB), which uses graphene/MnO2 cathode, Zn cathode, and the aqueous electrolyte containing Zn2+ and Mn2+ ions, as shown in Figure 2. Here the M means the manganese and also the multivalent [5,6]. In this abstract we fully introduce our work related to the three bran-new rechargeable MIBs and supercapacitors resulting from two concepts (Multivalent ion storage mechanism and MRR/MOR). The multivalent zinc ion (Zn2+), nickel ion (Ni2+ ), and manganese ion (Mn2+) batteries deliver a very high capacity ranging from 200 to 4000 mAh/g, a high energy density (ranging from 60 to 1000 Wh/Kg), a fast charge ability (within 2 minutes), and a long cycle life (10,000 cycles). Our results indicate that multivalent ion storage mechanism and MRR/MOR render a new class of energy conversion or storage systems and the new MIBs open possibility that the electric vehicles run much more miles at one charge than lithium ion batteries. Acknowledgements We would like to thank Shenzhen Technical Plan Projects (JCYJ20130402145002425) for financial support.