At a 5 C cycling rate, a capacity retention of 91% was sustained after 500 cycles, with very low capacity fade (<1%) during the initial 300 cycles. The team attributed the performance to the porous 1D nanostructures that can accommodate strain relaxation by slippage at the subunits wall boundaries and that provide short Li-ion diffusion distance along the confined dimension.

Nanomaterials chemistry has recently been the main impetus for electrochemical devices with advanced energy conversion and storage such as rechargeable lithium- ion batteries (LIBs). Nanostructured active materials with confined dimensions benefit fast Li⁺ transport due to dramatically decreased distance over which Li⁺ must diffuse in the solid state. Designing a one-dimensional (1D) nanoporous structure is one of the most favorable strategies to improve the electrode performance. 1D nanostructures provide short transport path along the confined radial dimension, while the connected porous framework could not only allow for efficient active mass-electrolyte contact but also accommodate better the strains related to the structural transformation upon repeated Li⁺ insertion/extraction.

Spinel LiNi_0.5Mn_1.5O₄ (LNMO), which possesses fast three-dimensional Li⁺ diffusion channels and high operational voltage (∼4.7 V versus Li⁺/Li0), is a promising high-power cathode material with low cost and less environmental impact. However, it remains challenging to achieve simultaneously remarkable rate capacity and cyclability for LNMO due to complex performance-influencing factors and electrolyte/ structure instability under high potentials.

...Herein, we present a morphology-inheritance route to prepare 1D nanoporous LNMO, which, to the best of our knowledge, has never been reported and electrochemically investigated to date.

—Zhang et al.

Resources

• Xiaolong Zhang, Fangyi Cheng, Jingang Yang, and Jun Chen (2013) LiNi_0.5Mn_1.5O₄ Porous Nanorods as High-Rate and Long-Life Cathodes for Li-Ion Batteries. Nano Letters doi: 10.1021/nl401072x