Among various energy storage devices, rechargeable ion batteries (RIBs) have been commercialized in portable electronic devices, electric vehicles, etc., thanks to their advantages of excellent reversibility, long lifespan, high safety and easy-to-operate property. With the shortage of lithium and cobalt resources and the promotion of renewable energy sources, high efficient RIBs with low-cost and environmental friendly merit are urgently required, whereas their developments are limited by the lack of suitable cathode materials. Compared with other candidates, polyanionic compounds have shown virtues of diversity, structural fruitfulness, adjustable working potential and great stability, and therefore are promising cathode materials for promoting the application of next-generation RIBs. In this paper, polyanion cathode materials are systematically classified into phosphate, sulfate, single polyanion and mixed polyanion, and the crystal structure and electrochemical properties of various cathode materials are introduced in detail with LiFePO4, Na3V2(PO4)3, NaVPO4F, Na2Fe2(SO4)3, Li2FeSiO4, etc. as the representative compounds. The research progress of various kinds of polyanionic cathode materials is reviewed, and the research achievements of coating, doping and nanocrystallization of the materials are briefly summarized. Finally, the bottleneck in the development of polyanionic cathode materials, i.e., low electronic conductivity, is discussed, and the corresponding solutions are proposed.
Keywords:second ion batteries
;
cathode
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polyanionic compounds
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challenges and strategies
Fig. 1
(a) crystal structure of LiFePO4[8]; (b) mossbauer map of LiFePO4 half cell after the first charge-discharge cycle[9]; (c) discharge voltage curve of MWCNT-90% LiFePO4 half battery at different discharge rates[13]; (d) cyclic performance curve of MWCNT-90% LiFePO4 half cell at 170 mA/g current density[13]
Fig. 2
(a) crystal structure of Na3V2(PO4)2F3 [8]; (b) charge-discharge curve of the first cycle of Na3V2(PO4)2F3 half cell at a current density of 0.045 C and 0.091 C[27]; (c) potential-composition electrochemical curves obtained upon Na+ extraction from Na3V2(PO4)2F3 [13]; (d) rate performance of Na3V2(PO4)2F3-Ti2+0.1 half cell[28]
Fig. 3
(a) crystal structure of Na4M3(PO4)2(P2O7)(M=Fe、Mn、Co、Ni)[38]; (b) galvanostatic charge-discharge curves of NFPP/C-500 cycled at 0.05 C[39]; (c) long-term cycling performance of NFPP/C-500 at 0.5 C[39]; (d) lattice parameters of NFPP/C-500 during the first charge process as a function of sodium concentration estimated from the electrochemical charge current[39]
Fig. 4
(a) crystal structure of Na2Fe2(SO4)3; (b) charge and dis-charge curve of the first five cycles of Na2Fe2(SO4)3 at a rate of C/20; (c) capacity retention upon cycling up to 30 cycles under various rate of C/20 to 20C; (d) Migration activation energy of Na-ion calculated with DFT[41]
Fig. 6
(a) crystal structure of Li2FeSiO4[58]; (b) variation of potential with state of charge on cycling Li2FeSiO4 at a rate of C/16[60]; (c) charge and discharge voltage profiles of Li2FeSiO4/C at a current density corresponding to C/50 rate[61]; (d) crystal structure of LiFeBO3[62]; (e) typical charge and discharge curves of LiFeBO3 cell[63]; (f) the cycle stability of the LiFeBO3 and C-LiFeBO3 at different current densities[(1)5, (2)10, (3) 20 and (4) 50 mA/g][63]
Fig. 7
(a) crystal structure of Li2Fe(C2O4)2[64]; (b) schematic illustration of iron and oxalate redox mechanism and their contribution to capacity in the stabilized charging and discharging process[64]; (c) crystal structure of KFeC2O4F[70]; (d) galvanostatic charge-discharge curves of KFeC2O4F in K half-cells[70]; (e) the corresponding charge-discharge curves of different cycles of full K ion cell[70]
Fig. 8
(a) crystal structure of Na2Fe(C2O4)SO4·H2O; (b) galvanostatic charge-discharge curves at 0.2 C; (c) long-term cycling performance of the NFOS/Na half cells at 0.5 C for 500cycles[76]
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... [8];(b) LiFePO4半电池首圈充放电循环后的穆斯堡尔图谱[9];(c) 不同放电速率下MWCNT-90% LiFePO4半电池的放电电压曲线[13];(d) 在170 mA/g的电流密度下MWCNT-90% LiFePO4半电池的循环性能曲线[13](a) crystal structure of LiFePO4[8]; (b) mossbauer map of LiFePO4 half cell after the first charge-discharge cycle[9]; (c) discharge voltage curve of MWCNT-90% LiFePO4 half battery at different discharge rates[13]; (d) cyclic performance curve of MWCNT-90% LiFePO4 half cell at 170 mA/g current density[13]Fig. 1
... [8]; (b) mossbauer map of LiFePO4 half cell after the first charge-discharge cycle[9]; (c) discharge voltage curve of MWCNT-90% LiFePO4 half battery at different discharge rates[13]; (d) cyclic performance curve of MWCNT-90% LiFePO4 half cell at 170 mA/g current density[13]Fig. 1
(a) crystal structure of Na3V2(PO4)2F3 [8]; (b) charge-discharge curve of the first cycle of Na3V2(PO4)2F3 half cell at a current density of 0.045 C and 0.091 C[27]; (c) potential-composition electrochemical curves obtained upon Na+ extraction from Na3V2(PO4)2F3 [13]; (d) rate performance of Na3V2(PO4)2F3-Ti2+0.1 half cell[28]Fig. 2
... [9];(c) 不同放电速率下MWCNT-90% LiFePO4半电池的放电电压曲线[13];(d) 在170 mA/g的电流密度下MWCNT-90% LiFePO4半电池的循环性能曲线[13](a) crystal structure of LiFePO4[8]; (b) mossbauer map of LiFePO4 half cell after the first charge-discharge cycle[9]; (c) discharge voltage curve of MWCNT-90% LiFePO4 half battery at different discharge rates[13]; (d) cyclic performance curve of MWCNT-90% LiFePO4 half cell at 170 mA/g current density[13]Fig. 1
... [9]; (c) discharge voltage curve of MWCNT-90% LiFePO4 half battery at different discharge rates[13]; (d) cyclic performance curve of MWCNT-90% LiFePO4 half cell at 170 mA/g current density[13]Fig. 1
(a) crystal structure of LiFePO4[8]; (b) mossbauer map of LiFePO4 half cell after the first charge-discharge cycle[9]; (c) discharge voltage curve of MWCNT-90% LiFePO4 half battery at different discharge rates[13]; (d) cyclic performance curve of MWCNT-90% LiFePO4 half cell at 170 mA/g current density[13]Fig. 1
... [13](a) crystal structure of LiFePO4[8]; (b) mossbauer map of LiFePO4 half cell after the first charge-discharge cycle[9]; (c) discharge voltage curve of MWCNT-90% LiFePO4 half battery at different discharge rates[13]; (d) cyclic performance curve of MWCNT-90% LiFePO4 half cell at 170 mA/g current density[13]Fig. 1
(a) crystal structure of Na3V2(PO4)2F3 [8]; (b) charge-discharge curve of the first cycle of Na3V2(PO4)2F3 half cell at a current density of 0.045 C and 0.091 C[27]; (c) potential-composition electrochemical curves obtained upon Na+ extraction from Na3V2(PO4)2F3 [13]; (d) rate performance of Na3V2(PO4)2F3-Ti2+0.1 half cell[28]Fig. 2
... [25];(b) Na3V2(PO4)2F3半电池在0.045 C、0.091 C电流密度下首圈充放电曲线[26];(c) Na3V2(PO4)2F3的GITT曲线[27];(d) Na3V2(PO4)2F3-Ti2+0.1半电池在不同电流密度下循环性能曲线[28](a) crystal structure of Na3V2(PO4)2F3 [8]; (b) charge-discharge curve of the first cycle of Na3V2(PO4)2F3 half cell at a current density of 0.045 C and 0.091 C[27]; (c) potential-composition electrochemical curves obtained upon Na+ extraction from Na3V2(PO4)2F3 [13]; (d) rate performance of Na3V2(PO4)2F3-Ti2+0.1 half cell[28]Fig. 2
... [26];(c) Na3V2(PO4)2F3的GITT曲线[27];(d) Na3V2(PO4)2F3-Ti2+0.1半电池在不同电流密度下循环性能曲线[28](a) crystal structure of Na3V2(PO4)2F3 [8]; (b) charge-discharge curve of the first cycle of Na3V2(PO4)2F3 half cell at a current density of 0.045 C and 0.091 C[27]; (c) potential-composition electrochemical curves obtained upon Na+ extraction from Na3V2(PO4)2F3 [13]; (d) rate performance of Na3V2(PO4)2F3-Ti2+0.1 half cell[28]Fig. 2
... [27];(d) Na3V2(PO4)2F3-Ti2+0.1半电池在不同电流密度下循环性能曲线[28](a) crystal structure of Na3V2(PO4)2F3 [8]; (b) charge-discharge curve of the first cycle of Na3V2(PO4)2F3 half cell at a current density of 0.045 C and 0.091 C[27]; (c) potential-composition electrochemical curves obtained upon Na+ extraction from Na3V2(PO4)2F3 [13]; (d) rate performance of Na3V2(PO4)2F3-Ti2+0.1 half cell[28]Fig. 2
... [28](a) crystal structure of Na3V2(PO4)2F3 [8]; (b) charge-discharge curve of the first cycle of Na3V2(PO4)2F3 half cell at a current density of 0.045 C and 0.091 C[27]; (c) potential-composition electrochemical curves obtained upon Na+ extraction from Na3V2(PO4)2F3 [13]; (d) rate performance of Na3V2(PO4)2F3-Ti2+0.1 half cell[28]Fig. 2
... [38];(b) NFPP/C半电池在0.05 C电流密度下前两圈充放电曲线[39];(c) NFPP/C半电池在0.5 C电流密度下循环性能[39];(d) NFPP/C脱钠过程中晶胞参数与体积变化图(1 Å=10-10 nm)[39](a) crystal structure of Na4M3(PO4)2(P2O7)(M=Fe、Mn、Co、Ni)[38]; (b) galvanostatic charge-discharge curves of NFPP/C-500 cycled at 0.05 C[39]; (c) long-term cycling performance of NFPP/C-500 at 0.5 C[39]; (d) lattice parameters of NFPP/C-500 during the first charge process as a function of sodium concentration estimated from the electrochemical charge current[39]Fig. 3
... [38]; (b) galvanostatic charge-discharge curves of NFPP/C-500 cycled at 0.05 C[39]; (c) long-term cycling performance of NFPP/C-500 at 0.5 C[39]; (d) lattice parameters of NFPP/C-500 during the first charge process as a function of sodium concentration estimated from the electrochemical charge current[39]Fig. 3
... [38];(b) NFPP/C半电池在0.05 C电流密度下前两圈充放电曲线[39];(c) NFPP/C半电池在0.5 C电流密度下循环性能[39];(d) NFPP/C脱钠过程中晶胞参数与体积变化图(1 Å=10-10 nm)[39](a) crystal structure of Na4M3(PO4)2(P2O7)(M=Fe、Mn、Co、Ni)[38]; (b) galvanostatic charge-discharge curves of NFPP/C-500 cycled at 0.05 C[39]; (c) long-term cycling performance of NFPP/C-500 at 0.5 C[39]; (d) lattice parameters of NFPP/C-500 during the first charge process as a function of sodium concentration estimated from the electrochemical charge current[39]Fig. 3
... [38]; (b) galvanostatic charge-discharge curves of NFPP/C-500 cycled at 0.05 C[39]; (c) long-term cycling performance of NFPP/C-500 at 0.5 C[39]; (d) lattice parameters of NFPP/C-500 during the first charge process as a function of sodium concentration estimated from the electrochemical charge current[39]Fig. 3
... [39];(c) NFPP/C半电池在0.5 C电流密度下循环性能[39];(d) NFPP/C脱钠过程中晶胞参数与体积变化图(1 Å=10-10 nm)[39](a) crystal structure of Na4M3(PO4)2(P2O7)(M=Fe、Mn、Co、Ni)[38]; (b) galvanostatic charge-discharge curves of NFPP/C-500 cycled at 0.05 C[39]; (c) long-term cycling performance of NFPP/C-500 at 0.5 C[39]; (d) lattice parameters of NFPP/C-500 during the first charge process as a function of sodium concentration estimated from the electrochemical charge current[39]Fig. 3
... [39];(d) NFPP/C脱钠过程中晶胞参数与体积变化图(1 Å=10-10 nm)[39](a) crystal structure of Na4M3(PO4)2(P2O7)(M=Fe、Mn、Co、Ni)[38]; (b) galvanostatic charge-discharge curves of NFPP/C-500 cycled at 0.05 C[39]; (c) long-term cycling performance of NFPP/C-500 at 0.5 C[39]; (d) lattice parameters of NFPP/C-500 during the first charge process as a function of sodium concentration estimated from the electrochemical charge current[39]Fig. 3
... [39](a) crystal structure of Na4M3(PO4)2(P2O7)(M=Fe、Mn、Co、Ni)[38]; (b) galvanostatic charge-discharge curves of NFPP/C-500 cycled at 0.05 C[39]; (c) long-term cycling performance of NFPP/C-500 at 0.5 C[39]; (d) lattice parameters of NFPP/C-500 during the first charge process as a function of sodium concentration estimated from the electrochemical charge current[39]Fig. 3
... [39]; (c) long-term cycling performance of NFPP/C-500 at 0.5 C[39]; (d) lattice parameters of NFPP/C-500 during the first charge process as a function of sodium concentration estimated from the electrochemical charge current[39]Fig. 3
... [39]; (d) lattice parameters of NFPP/C-500 during the first charge process as a function of sodium concentration estimated from the electrochemical charge current[39]Fig. 3
... [41](a) crystal structure of Na2Fe2(SO4)3; (b) charge and dis-charge curve of the first five cycles of Na2Fe2(SO4)3 at a rate of C/20; (c) capacity retention upon cycling up to 30 cycles under various rate of C/20 to 20C; (d) Migration activation energy of Na-ion calculated with DFT[41]Fig. 4
... [58];(b) Li2FeSiO4半电池在C/16下的充放电曲线[60];(c) Li2FeSiO4/C半电池在C/50下的充放电曲线[61];(d) LiFeBO3晶胞结构示意图[62];(e) LiFeBO3半电池充放电曲线[63];(f) LiFeBO3和碳包覆LiFeBO3(C-LiFeBO3)半电池在不同电流密度下的循环性能曲线[(1)5、(2)、(3)20和(4)50 mA/g][63](a) crystal structure of Li2FeSiO4[58]; (b) variation of potential with state of charge on cycling Li2FeSiO4 at a rate of C/16[60]; (c) charge and discharge voltage profiles of Li2FeSiO4/C at a current density corresponding to C/50 rate[61]; (d) crystal structure of LiFeBO3[62]; (e) typical charge and discharge curves of LiFeBO3 cell[63]; (f) the cycle stability of the LiFeBO3 and C-LiFeBO3 at different current densities[(1)5, (2)10, (3) 20 and (4) 50 mA/g][63]Fig. 6
... [58]; (b) variation of potential with state of charge on cycling Li2FeSiO4 at a rate of C/16[60]; (c) charge and discharge voltage profiles of Li2FeSiO4/C at a current density corresponding to C/50 rate[61]; (d) crystal structure of LiFeBO3[62]; (e) typical charge and discharge curves of LiFeBO3 cell[63]; (f) the cycle stability of the LiFeBO3 and C-LiFeBO3 at different current densities[(1)5, (2)10, (3) 20 and (4) 50 mA/g][63]Fig. 6
... [60];(c) Li2FeSiO4/C半电池在C/50下的充放电曲线[61];(d) LiFeBO3晶胞结构示意图[62];(e) LiFeBO3半电池充放电曲线[63];(f) LiFeBO3和碳包覆LiFeBO3(C-LiFeBO3)半电池在不同电流密度下的循环性能曲线[(1)5、(2)、(3)20和(4)50 mA/g][63](a) crystal structure of Li2FeSiO4[58]; (b) variation of potential with state of charge on cycling Li2FeSiO4 at a rate of C/16[60]; (c) charge and discharge voltage profiles of Li2FeSiO4/C at a current density corresponding to C/50 rate[61]; (d) crystal structure of LiFeBO3[62]; (e) typical charge and discharge curves of LiFeBO3 cell[63]; (f) the cycle stability of the LiFeBO3 and C-LiFeBO3 at different current densities[(1)5, (2)10, (3) 20 and (4) 50 mA/g][63]Fig. 6
... [60]; (c) charge and discharge voltage profiles of Li2FeSiO4/C at a current density corresponding to C/50 rate[61]; (d) crystal structure of LiFeBO3[62]; (e) typical charge and discharge curves of LiFeBO3 cell[63]; (f) the cycle stability of the LiFeBO3 and C-LiFeBO3 at different current densities[(1)5, (2)10, (3) 20 and (4) 50 mA/g][63]Fig. 6
... [61];(d) LiFeBO3晶胞结构示意图[62];(e) LiFeBO3半电池充放电曲线[63];(f) LiFeBO3和碳包覆LiFeBO3(C-LiFeBO3)半电池在不同电流密度下的循环性能曲线[(1)5、(2)、(3)20和(4)50 mA/g][63](a) crystal structure of Li2FeSiO4[58]; (b) variation of potential with state of charge on cycling Li2FeSiO4 at a rate of C/16[60]; (c) charge and discharge voltage profiles of Li2FeSiO4/C at a current density corresponding to C/50 rate[61]; (d) crystal structure of LiFeBO3[62]; (e) typical charge and discharge curves of LiFeBO3 cell[63]; (f) the cycle stability of the LiFeBO3 and C-LiFeBO3 at different current densities[(1)5, (2)10, (3) 20 and (4) 50 mA/g][63]Fig. 6
... [61]; (d) crystal structure of LiFeBO3[62]; (e) typical charge and discharge curves of LiFeBO3 cell[63]; (f) the cycle stability of the LiFeBO3 and C-LiFeBO3 at different current densities[(1)5, (2)10, (3) 20 and (4) 50 mA/g][63]Fig. 6
(a) crystal structure of Li2FeSiO4[58]; (b) variation of potential with state of charge on cycling Li2FeSiO4 at a rate of C/16[60]; (c) charge and discharge voltage profiles of Li2FeSiO4/C at a current density corresponding to C/50 rate[61]; (d) crystal structure of LiFeBO3[62]; (e) typical charge and discharge curves of LiFeBO3 cell[63]; (f) the cycle stability of the LiFeBO3 and C-LiFeBO3 at different current densities[(1)5, (2)10, (3) 20 and (4) 50 mA/g][63]Fig. 6
... [62]; (e) typical charge and discharge curves of LiFeBO3 cell[63]; (f) the cycle stability of the LiFeBO3 and C-LiFeBO3 at different current densities[(1)5, (2)10, (3) 20 and (4) 50 mA/g][63]Fig. 6
(a) crystal structure of Li2FeSiO4[58]; (b) variation of potential with state of charge on cycling Li2FeSiO4 at a rate of C/16[60]; (c) charge and discharge voltage profiles of Li2FeSiO4/C at a current density corresponding to C/50 rate[61]; (d) crystal structure of LiFeBO3[62]; (e) typical charge and discharge curves of LiFeBO3 cell[63]; (f) the cycle stability of the LiFeBO3 and C-LiFeBO3 at different current densities[(1)5, (2)10, (3) 20 and (4) 50 mA/g][63]Fig. 6
... [63](a) crystal structure of Li2FeSiO4[58]; (b) variation of potential with state of charge on cycling Li2FeSiO4 at a rate of C/16[60]; (c) charge and discharge voltage profiles of Li2FeSiO4/C at a current density corresponding to C/50 rate[61]; (d) crystal structure of LiFeBO3[62]; (e) typical charge and discharge curves of LiFeBO3 cell[63]; (f) the cycle stability of the LiFeBO3 and C-LiFeBO3 at different current densities[(1)5, (2)10, (3) 20 and (4) 50 mA/g][63]Fig. 6
... [64];(b) Li2Fe(C2O4)2中铁和草酸盐氧化还原机理示意图[64];(c) KFeC2O4F的晶胞结构示意图[71];(d) KFeC2O4F半电池充放电曲线[71];(e) KFeC2O4F/软碳全电池不同循环圈数充放电曲线[71](a) crystal structure of Li2Fe(C2O4)2[64]; (b) schematic illustration of iron and oxalate redox mechanism and their contribution to capacity in the stabilized charging and discharging process[64]; (c) crystal structure of KFeC2O4F[70]; (d) galvanostatic charge-discharge curves of KFeC2O4F in K half-cells[70]; (e) the corresponding charge-discharge curves of different cycles of full K ion cell[70]Fig. 74 混合聚阴离子系列
... [64];(c) KFeC2O4F的晶胞结构示意图[71];(d) KFeC2O4F半电池充放电曲线[71];(e) KFeC2O4F/软碳全电池不同循环圈数充放电曲线[71](a) crystal structure of Li2Fe(C2O4)2[64]; (b) schematic illustration of iron and oxalate redox mechanism and their contribution to capacity in the stabilized charging and discharging process[64]; (c) crystal structure of KFeC2O4F[70]; (d) galvanostatic charge-discharge curves of KFeC2O4F in K half-cells[70]; (e) the corresponding charge-discharge curves of different cycles of full K ion cell[70]Fig. 74 混合聚阴离子系列
... [64]; (b) schematic illustration of iron and oxalate redox mechanism and their contribution to capacity in the stabilized charging and discharging process[64]; (c) crystal structure of KFeC2O4F[70]; (d) galvanostatic charge-discharge curves of KFeC2O4F in K half-cells[70]; (e) the corresponding charge-discharge curves of different cycles of full K ion cell[70]Fig. 74 混合聚阴离子系列
... [64]; (c) crystal structure of KFeC2O4F[70]; (d) galvanostatic charge-discharge curves of KFeC2O4F in K half-cells[70]; (e) the corresponding charge-discharge curves of different cycles of full K ion cell[70]Fig. 74 混合聚阴离子系列
... [70]; (d) galvanostatic charge-discharge curves of KFeC2O4F in K half-cells[70]; (e) the corresponding charge-discharge curves of different cycles of full K ion cell[70]Fig. 74 混合聚阴离子系列
... [71];(d) KFeC2O4F半电池充放电曲线[71];(e) KFeC2O4F/软碳全电池不同循环圈数充放电曲线[71](a) crystal structure of Li2Fe(C2O4)2[64]; (b) schematic illustration of iron and oxalate redox mechanism and their contribution to capacity in the stabilized charging and discharging process[64]; (c) crystal structure of KFeC2O4F[70]; (d) galvanostatic charge-discharge curves of KFeC2O4F in K half-cells[70]; (e) the corresponding charge-discharge curves of different cycles of full K ion cell[70]Fig. 74 混合聚阴离子系列
... [71];(e) KFeC2O4F/软碳全电池不同循环圈数充放电曲线[71](a) crystal structure of Li2Fe(C2O4)2[64]; (b) schematic illustration of iron and oxalate redox mechanism and their contribution to capacity in the stabilized charging and discharging process[64]; (c) crystal structure of KFeC2O4F[70]; (d) galvanostatic charge-discharge curves of KFeC2O4F in K half-cells[70]; (e) the corresponding charge-discharge curves of different cycles of full K ion cell[70]Fig. 74 混合聚阴离子系列
... [71](a) crystal structure of Li2Fe(C2O4)2[64]; (b) schematic illustration of iron and oxalate redox mechanism and their contribution to capacity in the stabilized charging and discharging process[64]; (c) crystal structure of KFeC2O4F[70]; (d) galvanostatic charge-discharge curves of KFeC2O4F in K half-cells[70]; (e) the corresponding charge-discharge curves of different cycles of full K ion cell[70]Fig. 74 混合聚阴离子系列
... [75](a) crystal structure of Na2Fe(C2O4)SO4·H2O; (b) galvanostatic charge-discharge curves at 0.2 C; (c) long-term cycling performance of the NFOS/Na half cells at 0.5 C for 500cycles[76]Fig. 85 结论与展望