Post by pling on Feb 20, 2016 13:29:06 GMT
Fra nature.com 16. februar 2016
(Scientific Reports 6, Article number: 20656 )
Enhancing the energy density of safer Li-ion batteries by combining high-voltage lithium cobalt fluorophosphate cathodes and nanostructured titania anodes
- Recently, Li-ion batteries have been heavily scrutinized because of the apparent incompatibility between safety and high energy density. This work report a high voltage full battery made with TiO2/Li3PO4/Li2CoPO4F. The Li2CoPO4F cathode and TiO2 anode materials are synthesized by a sol–gel and anodization methods, respectively.
- Li-ion technology is now mature enough to meet the exacting demands of portable electronic devices and even electric vehicles. However, recently Li-ion batteries (LIBs) have come under heavy scrutiny because of an apparent incompatibility between safety and high energy density. The capabilities of LIBs are governed by the chemistry of the cathode, which almost exclusively utilizes transition metal insertion/intercalation reactions. The cathode material is not only the most expensive part of the battery but also the primary limitation on the electrochemical performance. It is thus desirable to find high voltage cathode materials with high capacity (xLi 1) and good electrolyte stability.
- On the other side of the battery, there are a large number of possibilities for anodes to be combined with cathodes, but some of the most outstanding anodes with respect to safety performance are Li4Ti5O12 and TiO2, which can replace carbonaceous materials. The TiO2 electrodes vs. Li2CoPO4F can be considered safer than other Li-ion systems based on carbon anodes, due to the higher working voltage of the anode that avoids lithium electrodeposition, which is well known to jeopardize safety, while energy density is preserved or even improved by the use of the high-voltage cathode.
- On the other side of the battery, there are a large number of possibilities for anodes to be combined with cathodes, but some of the most outstanding anodes with respect to safety performance are Li4Ti5O12 and TiO2, which can replace carbonaceous materials.
- Up until now, one of the more impressive LIB electrochemical performances has been seen in the Li4Ti5O12/Li2CoPO4F, primarily because it exhibits a voltage plateau at about 3.4 V which is higher than that of a Li4Ti5O12/LiFePO4 full cell at ~1.9 V. However, an unresolved problem with the former system is that capacity decays abruptly in the first few cycles, and as of yet no improvement in cycling performance has been achieved.
- In order to improve the cyclability of high voltage LIBs, the effects of a surface treatment of lithium phosphate on a full cell made with Li2CoPO4F as cathode and TiO2 as anode were studied. This report shows how the electrochemical performance of this material compared very favourably with Li3PO4-free electrodes. The introduction of an inactive matrix such as Li3PO4 for use as a buffer layer is expected to help the cyclability of the electrodes by allowing a rapid transportation of Li ions.
(Scientific Reports 6, Article number: 20656 )
Enhancing the energy density of safer Li-ion batteries by combining high-voltage lithium cobalt fluorophosphate cathodes and nanostructured titania anodes
- Recently, Li-ion batteries have been heavily scrutinized because of the apparent incompatibility between safety and high energy density. This work report a high voltage full battery made with TiO2/Li3PO4/Li2CoPO4F. The Li2CoPO4F cathode and TiO2 anode materials are synthesized by a sol–gel and anodization methods, respectively.
- Li-ion technology is now mature enough to meet the exacting demands of portable electronic devices and even electric vehicles. However, recently Li-ion batteries (LIBs) have come under heavy scrutiny because of an apparent incompatibility between safety and high energy density. The capabilities of LIBs are governed by the chemistry of the cathode, which almost exclusively utilizes transition metal insertion/intercalation reactions. The cathode material is not only the most expensive part of the battery but also the primary limitation on the electrochemical performance. It is thus desirable to find high voltage cathode materials with high capacity (xLi 1) and good electrolyte stability.
- On the other side of the battery, there are a large number of possibilities for anodes to be combined with cathodes, but some of the most outstanding anodes with respect to safety performance are Li4Ti5O12 and TiO2, which can replace carbonaceous materials. The TiO2 electrodes vs. Li2CoPO4F can be considered safer than other Li-ion systems based on carbon anodes, due to the higher working voltage of the anode that avoids lithium electrodeposition, which is well known to jeopardize safety, while energy density is preserved or even improved by the use of the high-voltage cathode.
- On the other side of the battery, there are a large number of possibilities for anodes to be combined with cathodes, but some of the most outstanding anodes with respect to safety performance are Li4Ti5O12 and TiO2, which can replace carbonaceous materials.
- Up until now, one of the more impressive LIB electrochemical performances has been seen in the Li4Ti5O12/Li2CoPO4F, primarily because it exhibits a voltage plateau at about 3.4 V which is higher than that of a Li4Ti5O12/LiFePO4 full cell at ~1.9 V. However, an unresolved problem with the former system is that capacity decays abruptly in the first few cycles, and as of yet no improvement in cycling performance has been achieved.
- In order to improve the cyclability of high voltage LIBs, the effects of a surface treatment of lithium phosphate on a full cell made with Li2CoPO4F as cathode and TiO2 as anode were studied. This report shows how the electrochemical performance of this material compared very favourably with Li3PO4-free electrodes. The introduction of an inactive matrix such as Li3PO4 for use as a buffer layer is expected to help the cyclability of the electrodes by allowing a rapid transportation of Li ions.