Configure EpehemeralStorage for ECS TaskDefinition via CloudFormation Template

I need an additional storage of 150GB (Launch type is Fargate) , so i am using EpehemeralStorage in my template to configure that,but once i deploy the template it's throwing me below error :

Resource handler returned message: "Model validation failed (#: extraneous key [EphemeralStorage] is not permitted)" (RequestToken: xyz, HandlerErrorCode: InvalidRequest)

Below is my Template.yaml :

Resources:
  Cluster:
    Type: AWS::ECS::Cluster
    Properties:
      ClusterName: newCluster

  TaskDefinition:
    Type: AWS::ECS::TaskDefinition
    Properties:
      NetworkMode: awsvpc
      RequiresCompatibilities:
        - FARGATE
      Cpu: 4096
      Memory: 16GB

      ExecutionRoleArn: !Ref ExecutionRole
      TaskRoleArn: !Ref TaskRole
      ContainerDefinitions:
        - Name: !Ref ServiceName
          Image: !Ref Image
          PortMappings:
            - ContainerPort: !Ref ContainerPort
          EphemeralStorage:
            SizeInGiB: 150

  ExecutionRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: !Join ['', [!Ref ServiceName, ExecutionRole]]
      AssumeRolePolicyDocument:
        Statement:
          - Effect: Allow
            Principal:
              Service: ecs-tasks.amazonaws.com
            Action: 'sts:AssumeRole'
      ManagedPolicyArns:
        - 'arn:aws:iam::aws:policy/service-role/AmazonECSTaskExecutionRolePolicy'

  TaskRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: !Join ['', [!Ref ServiceName, TaskRole]]
      AssumeRolePolicyDocument:
        Statement:
          - Effect: Allow
            Principal:
              Service: ecs-tasks.amazonaws.com
            Action: 'sts:AssumeRole'