Crystal-structure-matched FePO₄ Surface-coating on LiCoPO₄/MWCNT Nanocomposites for Long Lifecycle 5 V Class Lithium Ion Batteries

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Stable high-voltage operation of LiCoPO₄ (LCP) was successfully achieved via crystal-structure-matched surface coating using FePO₄ (FP) with an identical olivine structure to the LCP. The efficient formation of Fe³⁺-rich surface together with the partial dissolution of Fe³⁺ into LCP matrix yielded the excellent cycle performance with 99% of capacity retention at 100^th cycle, with a minimized Fe³⁺ dosage compared to the methods previously reported. This work confirms that the existence of the Fe³⁺ on the LCP surface is an important factor to bring about the stability of electrode/electrolyte interface.