Flexible graphene-based lithium ion batteries with ultrafast charge and discharge rates

Abstract

There is growing interest in thin, lightweight, and flexible energy storage devices to meet the special needs for next-generation, high-performance, flexible electronics. Here we report a thin, lightweight, and flexible lithium ion battery made from graphene foam, a three-dimensional, flexible, and conductive interconnected network, as a current collector, loaded with Li 4 Ti 5 O 12 and LiFePO 4 , for use as anode and cathode, respectively. No metal current collectors, conducting additives, or binders are used. The excellent electrical conductivity and pore structure of the hybrid electrodes enable rapid electron and ion transport. For example, the Li 4 Ti 5 O 12 / graphene foam electrode shows a high rate up to 200 C, equivalent to a full discharge in 18 s. Using them, we demonstrate a thin, lightweight, and flexible full lithium ion battery with a high-rate performance and energy density that can be repeatedly bent to a radius of 5 mm without structural failure and performance loss.flexible device | full battery T he development of next-generation flexible electronics (1), such as soft, portable electronic products, roll-up displays, wearable devices, implantable biomedical devices, and conformable health-monitoring electronic skin, requires power sources that are flexible (2, 3). Similar to conventional energy storage devices, flexible power sources with high capacity and rate performance that enable electronic devices to be continuously used for a long time and fully charged in a very short time are very important for applications of high-performance flexible electronics (4-7). Lithium ion batteries (LIBs) have a high capacity but usually suffer from a low charge/discharge rate compared with another important electrochemical storage device, supercapacitors. Therefore, it is highly desired to fabricate a flexible electrochemical energy storage system with a supercapacitor-like fast charge/discharge rate and battery-like high capacity. However, the fabrication of such an energy storage device remains a great challenge owing to the lack of reliable materials that combine superior electron and ion conductivity, robust mechanical flexibility, and excellent corrosion resistance in electrochemical environments.Using nano-sized materials to prepare electrodes is one of the most promising routes toward flexible batteries. Metal oxide nanowires (8, 9) and carbon nanomaterials such as carbon nanotubes (6, 10-12) and graphene paper (13) have been recently demonstrated for use in flexible LIBs. However, electron transport in these electrodes is slow because of the relatively low quality of nanomaterials (such as chemically derived graphene) and/or high junction contact resistance between them. As a consequence, only a moderate charge/discharge rate has been obtained in these flexible batteries. It is generally believed that the charge/discharge rate of a LIB depends critically on the migration rate of lithium ions and electrons through the electrolyte and bulk electrodes into active electrode materials. Strategies to inc...

Critical Insight into the Relentless Progression Toward Graphene and Graphene‐Containing Materials for Lithium‐Ion Battery Anodes

“…H.-M. Cheng et al [ 378 ] produced a fl exible battery using graphene foam (obtained by CVD) in both the anode (containing LTO) and the cathode (containing LiFePO 4 ) enabling an energy density of ≈110 Wh kg −1 (based on the total mass of the anode and cathode active material) and showing a stable cycling behavior (even under bending) for more than 40 cycles at 0.2 C rate. It also showed a rather low 1 st cycle irreversible capacity (Table 3 ).…”

MoS2/Graphene Composite Paper for Sodium-Ion Battery Electrodes

“…10 % of the cell weight 42 in traditional negative electrodes. [43][44][45][46][47][48] Herein, we provide the first report of (a) synthesis of composite papers from acid functionalized MoS 2 and reduced graphene oxide flakes, (b) improved capacity and high efficiency reversible Na storage in the self-standing flexible MoS 2 /graphene electrodes at room temperatures, and (c) mechanical characterization that highlight the high strain to failure in these composite papers.…”

Recent Progress in Self‐Supported Metal Oxide Nanoarray Electrodes for Advanced Lithium‐Ion Batteries

“…As described above, the Li 4 Ti 5 O 12 nanosheet arrays grown on 3D graphene foam (LTO/GF) exhibited outstanding cycling and rate performance in LIB half‐cell tests 132. When the LTO/GF anode was combined with a cathode with LiFePO 4 nanoparticles on graphene foam (LFP/GF), a flexible LTO/GF//LFP/GF full battery with high rate performance and energy density were realized ( Figure 14 a).…”

“…For example, Li 4 Ti 5 O 12 nanosheet arrays on 3D graphene foam (LTO/GF) were fabricated via a simple hydrothermal process 132. When investigated as a binder‐free anode in LIBs, the LTO/GF electrode showed not only excellent cycling stability with a specific capacity around 150 mAh g –1 at 30 C (1 C = 175 mAh g –1 ) and 130 mAh g –1 at 100 C after 500 cycles, but also an outstanding rate performance with a specific capacity of 86 mAh g –1 at 200 C (corresponding to an 18 s full discharge).…”

“…b) Charging/discharging voltage curves of LTO/GF//LFP/GF full battery with different current rates in the voltage range of 1.0–2.5 V. c) Cyclic performance of a flexible LTO/GF//LFP/GF full battery at a constant 10C rate for 100 cycles. Reproduced with permission 132. Copyright 2012, National Academy of Sciences.…”