Introduction There exists a poor contact between the current collector and the electrode due to the warping of planar solid oxide fuel cells and the uneven compressive forces of the stack. In the operation of solid oxide fuel cells (SOFCs), the poor contact between the current collector and the electrode can result in a contact resistance, thereby severely deteriorating the electrical performance of SOFCs. To optimize the current collection performance of SOFCs, it is necessary to conduct the experimental research and numerical simulation on the impact of current collector on the performance of planar SOFCs. Methods The fuel cell samples were provided by Xuzhou Huatsing Jingkun Energy Co., Ltd., China. The long anode-supported SOFC samples were prepared with cathode segmented to four insulted areas of 2.0 cm×2.1 cm. Each region was covered with different areas of silver mesh to constitute differential contact resistances. This ensured the consistency in the sample cell preparation and cell installation process, aside from the variations in the current collection. To enhance fuel sealing, the anode-side test fixture was made from a single metal plate, while the cathode-side fixture consisted of four metal blocks and three insulating mica sheets. A model RD2-12-10 electric heating furnace (Zhongyang Co., China) was used to heat at a rate of 1 ℃/min to 720 ℃, and then the temperature was maintained. The current-voltage characteristics of the SOFC were measured by a model Kikusui PLZ664WA DC electronic load. The voltage signals from various regions were measured by a model JC-9600B/8 multi-channel voltmeter (Jiangsu Jiechuang Technology Co., Ltd., China). The electrochemical impedance spectroscopic tests were conducted by a model Zennium electrochemical workstation (Zahner Co., Germany) with a frequency range from 0.1 Hz to 100 kHz. The microstructure of the samples was measured using a model FESEM SU-8220 field emission scanning electron microscope (Hitachi Co., Ltd., Japan). An one-dimensional numerical model was constructed via the FORTRAN language, following the double-layer theory and the conductivity data were adopted in the model. The current distribution along the flow channel of the SOFC was simulated, and the simulated data were compared with the experimental results. Results and discussion The cathode conductivity is different at different temperatures. At 220 ℃, the cathode conductivity reaches a minimum value of 1 125 S/m. As 500 ℃, the conductivity rapidly increases to 6 066 S/m. The conductivity tends to stabilize, reaching 6 192 S/m at 720 ℃. In the electrochemical impedance spectroscopic tests, the hydrogen flow rate is 100 mL/min, and the airflow rate is 450 mL/min. Under open-circuit conditions, the real-axis impedance of the 25% silver mesh-covered area is greater than that of other areas. The real part of the impedance for regions 1 to 4 is 1.22, 0.44, 0.38 Ω-cm2, and 0.39 Ω-cm2, respectively. The voltage-current characteristics were measured under various operating conditions. When the hydrogen inlet flow rate is 50 mL/min, the area-specific polarization resistance for regions 1 to 4 is 2.22, 0.95, 0.77 Ω-cm2, and 0.64 Ω-cm2, with corresponding current densities of 0.19, 0.42, 0.56 A/cm2, and 0.72 A/cm2. When the hydrogen inlet flow rate increases to 150 mL/min, the corresponding area specific resistances (ASRs) are 2.07, 0.87, 0.60 Ω-cm2, and 0.53 Ω cm2, while the current densities are 0.21, 0.51, 0.75 A/cm, and 0.84 A/cm, respectively. The results simulated by a model reveal that a poor current collection can lead to a reduction in overall current output and uneven current density distribution. The results show that at an average output voltage of 0.57 V or an average current density of 0.5 A/cm2, the simulated values for regions 4 and 3 closely match the experimental results. However, region 2 exhibits some deviation, while region 1 shows the most significant discrepancy. In addition, the simulated results also demonstrate the distribution of electrode voltage and current density along the airflow direction in the fuel cell. Conclusions The cathode of industrial-sized finished SOFC was fabricated with a 50% (in mass) La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and 50% (in mass) Ce0.9Gd0.1O2-δ (GDC) composite. The experimental results showed that the electrical conductivity of the fabricated cathode was 6 192 S/m at 720 ℃. The electrical conductivity of the anode support layer made from a NiO/YSZ mixture was approximately 0.65×106 S/m at room temperature. The long anode-supported SOFC samples were prepared, with cathode segmented to four insulted areas of 2.0 cm×2.1 cm. Each region was covered with different areas of silver mesh to constitute differential contact resistances. The electrochemical impedance spectroscopic tests and current-voltage characteristic curve scans were carried out in each localized region. The experimental results indicated that the real impedance spectrum of the 25% silver mesh coverage area under open circuit conditions was greater than that of other regions. At the same output voltage, the current density decreased monotonically with the decrease of the silver mesh area. The electronic conductivities of the cathode and anode of the same type of SOFCs were measured. The tested parameters were substituted into a numerical model to simulate the current and voltage distributions along the flow channel direction. The simulated results showed that there existed an accumulative parallel current in the area not covered by the silver mesh. The total output current decreased and the current density distribution was uneven, affecting the electrode polarization process and deteriorating the output performance of SOFCs.