Hybrid Composites of LiMn₂O₄–Graphene as Rechargeable Electrodes in Energy Storage Devices

Abstract

In this study spinel‐lithium manganese oxide (LiMn2O4) powders were prepared by using a simple sol–gel method with polyvinyl alcohol (PVA), and further combined with a conductive additive, graphene, to produce a composite electrode material for improved performance. The effects of the variation in the ratios of binder (PVA) to LiMn2O4 precursor on the particle size and electrochemical behavior of the composite were studied. Particle sizes of <200 nm were obtained. An energy density of 17.36 Wh kg−1 was obtained at an operating voltage of 3.2 V for the pure LiMn2O4 sample tested against a graphene electrode. For simultaneously improving power density (current Li batteries have a low power density as a disadvantage) along with energy density, the LiMn2O4–graphene composite was chosen as an electrode material. LiMn2O4–graphene composite electrodes were prepared by electrophoretic co‐deposition. The ratio of LiMn2O4–graphene composite was optimized to 1:1 during the electrode study based on its electrochemical performance. An average energy density of 30 Wh kg−1, a specific capacity of 49 mAh g−1, and an enhanced power density of 800 W kg−1 at a discharge current of 0.5 A g−1 were obtained. Discharge behavior improved evidently for tests performed on composite electrodes with increased LiMn2O4 (1:1.3 graphene/LiMn2O4). An improved average energy density of 59.6 Wh kg−1 was obtained along with a power density of 697 W kg−1. The electrodes showed good performance during study of a button cell device. Such electrodes are well suited for hybrid energy storage devices having good energy and power density and bridging the gap between batteries and supercapacitors.

Effect of Different Binders on the Electrochemical Performance of Metal Oxide Anode for Lithium-Ion Batteries

“…In the last few years, lots of efforts have been paid attention to seek for alternative water soluble polymers to build up the electrochemical performance. For example, CMC [ 22 , 23 ], SBR [ 24 ], LA133 [ 25 , 26 ], polyacrylic acid (PAA) [ 27 , 28 ], polyvinyl alcohol (PVA) [ 29 , 30 ], polyethylene glycol (PEG has been successfully used in LIBs because it was cheaper, was environmentally friendly, and also has the better solubility) [ 20 ], and polyamide imide (PAI) [ 31 ] have possibly used water instead of NMP. Among aqueous-based binders, the system based on SBR and CMC was the most studied binder combination and can provide excellent cycling ability and mechanical stability to electrodes when abide the volume expansion during charge-discharge cycling.…”

Graphene‐Containing Nanomaterials for Lithium‐Ion Batteries

“…LiMn 2 O 4 is a 4.0 V cathode . Lithium cycling performance of ZnO‐ALD‐modified LiMn 2 O 4 /graphene possessing a capacity of 122 mAh g −1 after 100 electrochemical cycles was reported by Aziz et al A LiMn 2 O 4 –graphene composite produced by electrophoretic co‐deposition delivered an improved average energy density of 59.6 Wh kg −1 along with a power density of 697 W kg −1 …”

“…[ 386 ] Lithium cycling performance of ZnO-ALD-modifi ed LiMn 2 O 4 /graphene possessing a capacity of 122 mAh g −1 after 100 electrochemical cycles was reported by Aziz et al [ 387 ] A LiMn 2 O 4 -graphene composite produced by electrophoretic co-deposition delivered an improved average energy density of 59.6 Wh kg −1 along with a power density of 697 W kg −1 . [ 388 ] Other transition metals (such as nickel, cobalt and iron) were also incorporated into LiMn 2 O 4 to improve its properties. [ 389 ] Binary spinel structures, such as sandwiched LiNi 0.5 Mn 1.5 O 4 synthesized via sol-gel as a 5 V cathode, were recently discussed.…”

Highly Efficient Materials Assembly Via Electrophoretic Deposition for Electrochemical Energy Conversion and Storage Devices

“…The surface of graphene is readily modified by various surfactant charges, suggesting that the active materials‐graphene composite is suitable for EPD fabrication. For instance, a LiMn 2 O 4 ‐graphene cathode was synthesized by Sreelakshmi et al by EPD. Homemade nanosized LiMn 2 O 4 powders were applied as active material, graphene as conductive agent and nickel nitrate as surfactant.…”

“…It should be noted that the EPD effectiveness of cathode materials is correlated with nanosized active particles. To the authors’ best knowledge, only a few reports have been focused on this direction . In addition, the size and amount of additive particles are speculated to affect the topology of as‐deposited films.…”