Innovative BVO@CuO design: A high-performance vanadium-based anode material for Li-ion batteries

Herein, a specific structure of BVO coated on CuO@Cu current collector (denoted as BVO@CuO) was constructed in the study by merging a metal oxide (hollow cubic structure BiVO4) and a lithiophilic oxide (lithiophilic copper oxide array). The design-specific structure was recovered and a high-performance composite anode for LIBs (referred to as r-BVO@CuO) was built using a straightforward preferential reduction technique. Specifically, the lithiophilic copper oxide array is reduced to the nano-copper array, and the reduction products Bi and Li3VO4 of BVO are embedded in the nano-copper array. This structure can not only buffer the volume expansion of Bi during the transformation of Li and Bi into alloy but also prevents the dissolution of Li3VO4, which helps improve the cycle stability of the electrode and maintains a high capacity. At the same time, some copper particles enter into the electrode material, which has enhanced the electronic conductivity of the anode and improved the rate performance of the LIBs. Therefore, the r-BVO@CuO shows an excellent reversible capacity of 1052 mAh g−1 at 0.1 A g−1 (The theoretical capacity of graphite is 372 mAh g−1). The capacity retention of r-BVO@CuO is about 90.5% after 100 charge/discharge cycles. Meanwhile, X-ray diffraction and density functional calculation analyses are employed to demonstrate the alloy change process of r-BVO@CuO during electrochemical cycling. Subsequently, LIB full cells are constructed with r-BVO@CuO as the anode and lithium iron phosphate as the cathode assembly (denoted as LFP|r-BVO@CuO LIBs). The devices can reach ∼ 165 mAh g−1 at 1 C, which is higher than LFP|Li LIBs (140 mAh g−1) and LFP|r-BVO LIBs (90 mAh g−1). Although the voltage plateau of LFP|r-BVO@CuO LIBs is comparatively lower than that of LFP|Li LIBs, the energy density (413.8 Wh kg−1) is not significantly different from that of LFP|Li LIBs (449.9 Wh kg−1), for the cathode only. Interestingly, the device delivers a capacity of 134 mAh g−1 after 1100 charge-discharge cycles with a capacity retention of 85.3%. This work may be widely applied to manufacture BVO-type anodes to improve electrochemical performance in energy-related storage-related fields.