School of Materials Science and Engineering, Beihang University, Beijing 100083, China.
Nanoscale. 2018 Apr 26;10(16):7676-7684. doi: 10.1039/c8nr00692j.
High volumetric energy and power densities are crucial for Li-ion batteries, which are however hindered by the loose structure and/or insufficient conductivity of conventional electrode laminates. Herein, an efficiently conductive framework of graphene nanoribbons (GNRs) and graphene (G) is rationally constructed to wrap LiFePO4 (LFP) into a binder-free dense electrode by a coupling technique of spray deposition and vacuum filtration. The spray ensures a uniform mixing of LFP, G and GNRs, meanwhile the vacuum filtration leads to a dense packing of the mixture. With only 2 wt% of G and GNRs, the LFP/GNR/G electrode delivers a high rate capability and a stable (dis)charge cycling performance under high LFP loading conditions. Moreover, the dense LFP/GNR/G electrode exhibits superior volumetric properties among all the reported LFP electrodes on the basis of the entire electrode volume, including a Li storage capacity of 318 A h L-1, an energy density of 1020 W h L-1 and a power density of 5.1 kW L-1 at 5C rate. This unique assembly strategy and the electrode structure pave a new way for high-volumetric-performance batteries.
高体积能量和功率密度对于锂离子电池至关重要，但传统电极层压板的结构松散和/或导电性不足限制了其发展。在此，通过喷雾沉积和真空过滤相结合的方法，合理构建了由石墨烯纳米带（GNRs）和石墨烯（G）组成的高效导电框架，将 LiFePO4（LFP）包裹成无粘结剂致密电极。喷雾确保了 LFP、G 和 GNRs 的均匀混合，同时真空过滤导致混合物的紧密堆积。仅添加 2wt%的 G 和 GNRs，LFP/GNR/G 电极在高 LFP 负载条件下表现出高倍率性能和稳定的（充）放电循环性能。此外，基于整个电极体积，致密的 LFP/GNR/G 电极在所有已报道的 LFP 电极中表现出卓越的体积性能，包括 318 A h L-1 的储锂容量、1020 W h L-1 的能量密度和 5C 速率下 5.1kW L-1 的功率密度。这种独特的组装策略和电极结构为高体积性能电池开辟了新途径。
