Deficiencies of cathode materials severely limit cycling performance and discharge rates of Li batteries. The key problem is that cathode materials must combine multiple properties: high lithium ion intercalation capacity, electrical/ionic conductivity, porosity, and mechanical toughness. Some materials revealed promising characteristics in a subset of these properties, but attaining the entire set of often contrarian characteristics requires new methods of materials engineering. In this paper, we report high surface area 3D composite from reduced graphene oxide loaded with LiFePO4 (LFP) nanoparticles made by layer-by-layer assembly (LBL). High electrical conductivity of the LBL composite is combined with high ionic conductivity, toughness, and low impedance. As a result of such materials properties, reversible lithium storage capacity and Coulombic efficiency were as high as 148 mA h g(-1) and 99%, respectively, after 100 cycles at 1 C. Moreover, these composites enabled unusually high reversible charge-discharge rates up to 160 C with a storage capacity of 56 mA h g(-1), exceeding those of known LFP-based cathodes, some of them by several times while retaining high content of active cathode material. The study demonstrates that LBL-assembled composites enable resolution of difficult materials engineering tasks.
The demand for lithium-ion
batteries with both high power and high-energy
density has attracted widespread attention as energy-storage devices
for the increasing demand of consumer electronics, electric vehicles,
and grid-scale storage. However, the fabrication of an advanced electrode
architecture with high areal capacity, excellent cycling stability,
and superior rate performance remains a long-term challenge in the
development of advanced electrochemical energy-storage devices. Herein,
we design an effective and general strategy to spontaneously encapsulate
Ge nanoparticles into a three-dimensional double hydrophilic N-doped
ultrathin graphite/void/hydrophobic ultrathin graphite tube network
(Ge@3D-DHGT) with control over the position for large specific capacity
(1338 mA h g–1), high rate performance (752 mA h
g–1 at 40 C), and superior cycling stability (up
to 1000 cycles). Toward the practical application, the as-prepared
Ge@3D-DHGT electrode showed a large areal capacity (10 mA h cm–2 under 8 mA cm–2), which provides
a highly promising anode with both high capacity and high rate performance.
Importantly, this work provides an approach to fabricate high-areal-capacity
anodes with long cycling stability and rapid charge–discharge
properties with practical applications in advanced rechargeable batteries.
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